Endangered and Threatened Wildlife and Plants; Endangered Species for Prostrate Milkweed and Designation of Critical Habitat, 8509-8543 [2022-02544]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 87, Number 31 (Tuesday, February 15, 2022)]
[Proposed Rules]
[Pages 8509-8543]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-02544]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R2-ES-2021-0041; FF09E21000; FXES1111090FEDR 223]
RIN 1018-BE65


Endangered and Threatened Wildlife and Plants; Endangered Species 
for Prostrate Milkweed and Designation of Critical Habitat

AGENCY: Fish and Wildlife Service, Interior.

[[Page 8510]]


ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to 
list the prostrate milkweed (Asclepias prostrata), a plant species from 
Texas, as an endangered species and designate critical habitat under 
the Endangered Species Act of 1973, as amended (Act). This 
determination also serves as our 12-month finding on a petition to list 
the prostrate milkweed. After a review of the best available scientific 
and commercial information, we find that listing the species is 
warranted. Accordingly, we propose to list the prostrate milkweed as an 
endangered species. If we finalize this rule as proposed, it would add 
this species to the List of Endangered and Threatened Plants and extend 
the Act's protections to the species. We also propose to designate 
critical habitat for the prostrate milkweed under the Act. In total, 
approximately 691.3 acres (279.8 hectares) in Starr and Zapata 
Counties, Texas, fall within the boundaries of the proposed critical 
habitat designation. We also announce the availability of a draft 
economic analysis of the proposed designation of critical habitat for 
prostrate milkweed.

DATES: We will accept comments received or postmarked on or before 
April 18, 2022. Comments submitted electronically using the Federal 
eRulemaking Portal (see ADDRESSES, below) must be received by 11:59 
p.m. Eastern Time on the closing date. We must receive requests for a 
public hearing, in writing, at the address shown in FOR FURTHER 
INFORMATION CONTACT by April 1, 2022.

ADDRESSES: You may submit comments by one of the following methods:
    (1) Electronically: Go to the Federal eRulemaking Portal: https://www.regulations.gov. In the Search box, enter the docket number or RIN 
for this rulemaking (presented above in the document headings). For 
best results, do not copy and paste either number; instead, type the 
docket number or RIN into the Search box using hyphens. Then, click on 
the Search button. On the resulting page, in the panel on the left side 
of the screen, under the Document Type heading, check the Proposed Rule 
box to locate this document. You may submit a comment by clicking on 
``Comment.''
    (2) By hard copy: Submit by U.S. mail to: Public Comments 
Processing, Attn: FWS-R2-ES-2021-0041, U.S. Fish and Wildlife Service, 
MS: PRB/3W, 5275 Leesburg Pike, Falls Church, VA 22041-3803.
    We request that you send comments only by the methods described 
above. We will post all comments on https://www.regulations.gov. This 
generally means that we will post any personal information you provide 
us (see Information Requested, below, for more information).
    Availability of supporting materials: The species status assessment 
report and the draft economic analysis are available at https://www.regulations.gov under Docket No. FWS-R2-ES-2021-0041. For the 
critical habitat designation, the coordinates or plot points or both 
from which the maps are generated are included in the decision file and 
are available at https://www.fws.gov/southwest/es/TexasCoastal/, at 
https://www.regulations.gov under Docket No. FWS-R2-ES-2021-0041, and 
at the Texas Coastal Ecological Services Field Office (see FOR FURTHER 
INFORMATION CONTACT). Any additional tools or supporting information 
that we may develop for the critical habitat designation will also be 
available at the Service website and field office set out above and may 
also be included in this preamble and/or at https://www.regulations.gov.

FOR FURTHER INFORMATION CONTACT: Chuck Ardizzone, Field Supervisor, 
Texas Coastal Ecological Services Field Office, 17629 El Camino Real, 
Suite 211, Houston, TX 77058; telephone 281-286-8282. Persons who use a 
telecommunications device for the deaf (TDD) may call the Federal Relay 
Service at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Executive Summary

    Why we need to publish a rule. Under the Act, if we determine that 
a species warrants listing, we are required to promptly publish a 
proposal in the Federal Register, unless doing so is precluded by 
higher-priority actions and expeditious progress is being made to add 
and remove qualified species to or from the List of Endangered and 
Threatened Wildlife and Plants. The Service will make a determination 
on our proposal within 1 year. If there is substantial disagreement 
regarding the sufficiency and accuracy of the available data relevant 
to the proposed listing, we may extend the final determination for not 
more than six months. To the maximum extent prudent and determinable, 
we must designate critical habitat for any species that we determine to 
be an endangered or threatened species under the Act. Listing a species 
as an endangered or threatened species and designation of critical 
habitat can only be completed by issuing a rule.
    What this document does. We propose to list the prostrate milkweed 
as an endangered species under the Act, and we propose the designation 
of critical habitat for the species.
    The basis for our action. Under the Act, we may determine that a 
species is an endangered or threatened species because of any of five 
factors: (A) The present or threatened destruction, modification, or 
curtailment of its habitat or range; (B) overutilization for 
commercial, recreational, scientific, or educational purposes; (C) 
disease or predation; (D) the inadequacy of existing regulatory 
mechanisms; or (E) other natural or manmade factors affecting its 
continued existence. We have determined that competition from 
introduced invasive grass; habitat loss and degradations from root-
plowing and conversion of native vegetation to improved buffelgrass 
pasture; habitat loss from right of way (ROW) construction and 
maintenance from energy development and road and utility construction; 
habitat loss from border security development and enforcement 
activities (Factor A); and the demographic and genetic consequences of 
small population sizes (Factor E) are threats to the prostrate 
milkweed.
    Section 4(a)(3) of the Act requires the Secretary of the Interior 
(Secretary) to designate critical habitat concurrent with listing to 
the maximum extent prudent and determinable. Section 3(5)(A) of the Act 
defines critical habitat as: (i) The specific areas within the 
geographical area occupied by the species, at the time it is listed, on 
which are found those physical or biological features (I) essential to 
the conservation of the species and (II) which may require special 
management considerations or protections; and (ii) specific areas 
outside the geographical area occupied by the species at the time it is 
listed, upon a determination by the Secretary that such areas are 
essential for the conservation of the species. Section 4(b)(2) of the 
Act states that the Secretary must make the designation on the basis of 
the best scientific data available and after taking into consideration 
the economic impact, the impact on national security, and any other 
relevant impacts of specifying any particular area as critical habitat.

Information Requested

    We intend that any final action resulting from this proposed rule 
will be based on the best scientific and commercial data available and 
be as accurate and as effective as possible. Therefore, we request 
comments or information from other governmental

[[Page 8511]]

agencies, Native American Tribes, the scientific community, industry, 
or any other interested parties concerning this proposed rule.
    We particularly seek comments concerning:
    (1) The species' biology, range, and population trends, including:
    (a) Biological or ecological requirements of the species, including 
habitat requirements for feeding, breeding, and sheltering;
    (b) Genetics and taxonomy;
    (c) Historical and current range, including distribution patterns;
    (d) Historical and current population levels, and current and 
projected trends; and
    (e) Past and ongoing conservation measures for the species, its 
habitat, or both.
    (2) Factors that may affect the continued existence of the species, 
which may include habitat modification or destruction, overutilization, 
disease, predation, the inadequacy of existing regulatory mechanisms, 
or other natural or manmade factors.
    (3) Biological, commercial trade, or other relevant data concerning 
any threats (or lack thereof) to this species and existing regulations 
that may be addressing those threats.
    (4) Additional information concerning the historical and current 
status, range, distribution, and population size of this species, 
including the locations of any additional populations of this species.
    (5) The reasons why we should or should not designate habitat as 
``critical habitat'' under section 4 of the Act (16 U.S.C. 1531 et 
seq.), including information to inform the following factors that the 
regulations identify as reasons why designation of critical habitat may 
be not prudent:
    (a) The species is threatened by taking or other human activity and 
identification of critical habitat can be expected to increase the 
degree of such threat to the species;
    (b) The present or threatened destruction, modification, or 
curtailment of a species' habitat or range is not a threat to the 
species, or threats to the species' habitat stem solely from causes 
that cannot be addressed through management actions resulting from 
consultations under section 7(a)(2) of the Act;
    (c) Areas within the jurisdiction of the United States provide no 
more than negligible conservation value, if any, for a species 
occurring primarily outside the jurisdiction of the United States; or
    (d) No areas meet the definition of critical habitat.
    (6) Specific information on:
    (a) The amount and distribution of prostrate milkweed habitat;
    (b) What areas, that are occupied at the time of listing and that 
contain the physical or biological features essential to the 
conservation of the species, should be included in the designation and 
why;
    (c) Any additional areas occurring within the range of the species, 
including Starr and Zapata Counties, Texas, that should be included in 
the designation because they (1) are occupied at the time of listing 
and contain the physical or biological features that are essential to 
the conservation of the species and that may require special management 
considerations, or (2) are unoccupied at the time of listing and are 
essential for the conservation of the species;
    (d) Special management considerations or protection that may be 
needed in critical habitat areas we are proposing, including managing 
for the potential effects of climate change; and
    (e) What areas not occupied at the time of listing are essential 
for the conservation of the species. We particularly seek comments:
    (i) Regarding whether occupied areas are adequate for the 
conservation of the species;
    (ii) Providing specific information regarding whether or not 
unoccupied areas would, with reasonable certainty, contribute to the 
conservation of the species and contain at least one physical or 
biological feature essential to the conservation of the species; and
    (iii) Explaining whether or not unoccupied areas fall within the 
definition of ``habitat'' at 50 CFR 424.02 and why.
    (7) Land use designations and current or planned activities in the 
subject areas and their possible impacts on proposed critical habitat.
    (8) Any probable economic, national security, or other relevant 
impacts of designating any area that may be included in the final 
designation, and the related benefits of including or excluding 
specific areas.
    (9) Information on the extent to which the description of probable 
economic impacts in the draft economic analysis is a reasonable 
estimate of the likely economic impacts and any additional information 
regarding probable economic impacts that we should consider.
    (10) Whether any specific areas we are proposing for critical 
habitat designation should be considered for exclusion under section 
4(b)(2) of the Act, and whether the benefits of potentially excluding 
any specific area outweigh the benefits of including that area under 
section 4(b)(2) of the Act, in particular for the critical habitat 
units on privately owned lands. If you think we should exclude any 
additional areas, please provide credible information regarding the 
existence of a meaningful economic or other relevant impact supporting 
a benefit of exclusion.
    (11) Whether we could improve or modify our approach to designating 
critical habitat in any way to provide for greater public participation 
and understanding, or to better accommodate public concerns and 
comments.
    Please include sufficient information with your submission (such as 
scientific journal articles or other publications) to allow us to 
verify any scientific or commercial information you include.
    Please note that submissions merely stating support for, or 
opposition to, the action under consideration without providing 
supporting information, although noted, will not be considered in 
making a determination, as section 4(b)(1)(A) of the Act directs that 
determinations as to whether any species is an endangered or a 
threatened species must be made ``solely on the basis of the best 
scientific and commercial data available.''
    You may submit your comments and materials concerning this proposed 
rule by one of the methods listed in ADDRESSES. We request that you 
send comments only by the methods described in ADDRESSES.
    If you submit information via https://www.regulations.gov, your 
entire submission--including any personal identifying information--will 
be posted on the website. If your submission is made via a hardcopy 
that includes personal identifying information, you may request at the 
top of your document that we withhold this information from public 
review. However, we cannot guarantee that we will be able to do so. We 
will post all hardcopy submissions on https://www.regulations.gov.
    Comments and materials we receive, as well as supporting 
documentation we used in preparing this proposed rule, will be 
available for public inspection on https://www.regulations.gov.
    Because we will consider all comments and information we receive 
during the comment period, our final determinations may differ from 
this proposal. Based on the new information we receive (and any 
comments on that new information), we may conclude that the species is 
threatened instead of endangered, or we may conclude that the species 
does not warrant listing as either an endangered species or a 
threatened species. For critical habitat, our final designation may not 
include all areas proposed, may include some additional areas that meet 
the definition

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of critical habitat, and may exclude some areas if we find the benefits 
of exclusion outweigh the benefits of inclusion.

Public Hearing

    Section 4(b)(5) of the Act provides for a public hearing on this 
proposal, if requested. Requests must be received by the date specified 
in DATES. Such requests must be sent to the address shown in FOR 
FURTHER INFORMATION CONTACT. We will schedule a public hearing on this 
proposal, if requested, and announce the date, time, and place of the 
hearing, as well as how to obtain reasonable accommodations, in the 
Federal Register and local newspapers at least 15 days before the 
hearing. For the immediate future, we will provide these public 
hearings using webinars that will be announced on the Service's 
website, in addition to the Federal Register. The use of these virtual 
public hearings is consistent with our regulations at 50 CFR 
424.16(c)(3).

Previous Federal Actions

    On June 25, 2007, we received a petition, dated June 18, 2007, from 
Forest Guardians (now WildEarth Guardians) that included the prostrate 
milkweed. On December 16, 2009, we published a 90-day finding (74 FR 
66866) that the petition presented substantial information that 
prostrate milkweed may be warranted for listing. At that time, we 
initiated a status review of the species.

Supporting Documents

    A species status assessment (SSA) team prepared an SSA report for 
the prostrate milkweed. The SSA team was composed of Service 
biologists, in consultation with other species experts. The SSA report 
represents a compilation of the best scientific and commercial data 
available concerning the status of the species, including the impacts 
of past, present, and future factors (both negative and beneficial) 
affecting the species. In accordance with our joint policy on peer 
review published in the Federal Register on July 1, 1994 (59 FR 34270), 
and our August 22, 2016, memorandum updating and clarifying the role of 
peer review of listing actions under the Act, we sought the expert 
opinions of six appropriate specialists regarding the SSA report. The 
Service received two responses. The Service also sent the SSA report to 
one partner, a botanist from the Texas Parks and Wildlife Department, 
and received a review from this partner.

I. Proposed Listing Determination

Background

    A thorough review of the taxonomy, life history, and ecology of the 
prostrate milkweed (Asclepias prostrata) is presented in the SSA report 
(Service 2020, entire). Prostrate milkweed is an herbaceous, flowering 
plant in the Apocynaceae (dogbane) family. It is native to Texas, USA, 
and Tamaulipas and eastern Nuevo Le[oacute]n, Mexico.
    Prostrate milkweed is a perennial species with cream, yellow, 
greenish, or pinkish flowers (Blackwell 1964, p. 178). This species is 
distinctive in its prostrate habit; the leaves and stems sprawl outward 
along the surface of the ground. It is found in open spaces with full 
sun, and with little to no competition from surrounding plants (Poole 
and Janssen 1997, p. 117). It occurs in a subtropical, semiarid climate 
in sparsely vegetated habitats, including grasslands, savannas, and 
open areas of the Tamaulipan shrubland ecological region, on level or 
gently sloping uplands (Singhurst et al. 2015, p. 25; Carr 2011, pp. 
37-38; Damude and Poole 1990, p. 13; Strong and Williamson 2015, p. 
36). Prostrate milkweed occurs primarily in deep, loose, sandy soils 
formed over sandstone or indurated caliche (hardened soil layer 
cemented by calcium and magnesium carbonates) (Carr 2011, pp. 37-38; 
Strong and Williamson 2015, p. 36).
    Like all milkweeds, prostrate milkweed flowers have a unique and 
complex structure and pollination system. Pollinators are attracted to 
the copious nectar produced deep within the flower. To reach the 
nectar, insects of a particular size are forced against the flower's 
central stalk in such a way that pollinia, which are sack-like 
structures full of pollen grains, adhere to their legs. When the insect 
visits another flower of the same species, the pollinia are often 
wedged against the stigma (the receptive female structure) and detach, 
thus delivering a large load of pollen and effecting fertilization. The 
closely-related zizotes milkweed, Asclepias oenotheroides, is 
effectively pollinated by very large wasps called tarantula hawks 
(species of Pepsis and Hemipepsis), and it is likely that these wasps 
and large bees also pollinate prostrate milkweed. Due to their 
relatively large size and the abundance of nectar produced by the 
flowers, these pollinators are able to fly relatively large distances 
between nectar sources (Gathman and Tscharntke 2002, entire; Greenleaf 
et al. 2007, entire). Hence, it is likely that prostrate milkweed can 
reproduce even when individuals are widely distributed at very low 
densities, due to the uniquely effective pollination system, large 
nectar reward, and large forage range of its pollinators.
    Fertilized flowers of prostrate milkweed produce capsules with 
about 100 seeds each. The seeds have long, silky, white hairs and are 
dispersed by wind (Damude and Poole 1990, pp. 4-5; Richardson and King 
2011, p. 76). Seed production of milkweeds is often resource limited 
(La Rosa and Conner 2017, p. 151); resources for prostrate milkweed 
include rainfall, pollinators, and open, sparsely vegetated habitat.
    Prostrate milkweed remains as tubers, up to 12 inches (in) (30 
centimeters (cm)) underground that are dormant during long droughts. 
New stems are stimulated to emerge from the soil by infrequent, heavy 
rainfall, and set seed following wildfire or, historically, a passing 
herd of bison has cleared competing grasses and forbs, and the deluges 
of tropical storms briefly replenish moisture. The species exists where 
competition from other plants is periodically reduced by wildfire or 
grazing. These life-history traits allow the species to rebound after 
periods of inhospitable conditions, and well-managed livestock grazing, 
which simulates the effects of bison, and rangeland management, 
including brush thinning and prescribed burning, can return an 
unsuitable area to conditions more suitable for prostrate milkweed. As 
a result, sufficiently resilient prostrate milkweed populations may be 
maintained on well-managed rangelands. Livestock grazing is the primary 
economic use of privately-owned land throughout the range of prostrate 
milkweed in Texas and northeast Mexico, although the management regime 
of these rangelands is unknown. This adaptation also enables prostrate 
milkweed to occur along mowed road rights-of-way (ROWs) and in 
rangelands where soils are intact. Therefore, while there may be 
prostrate milkweed populations on these rangelands, we do not have 
evidence that they are present, nor do we have information that the 
grazing is managed in such a way as to promote resilient populations. 
However, it is unlikely to remain where soils are disturbed by plowing, 
bulldozing, or road grading because this destroys the tubers, 
preventing any plant regrowth.
    In the United States, prostrate milkweed occurs in south Texas from 
northwest Zapata County to the vicinity of Roma, in Starr County. All 
known U.S. populations are within 8 miles of the Rio Grande (Strong and 
Williamson 2015, pp. 34-35). In Mexico, known locations for this 
species occur in

[[Page 8513]]

isolated pockets widely scattered in northern Tamaulipas and eastern 
Nuevo Le[oacute]n, many over 100 miles (mi) (160 kilometers (km)) from 
the Rio Grande (Strong and Williamson 2015, p. 35). The historical 
range of prostrate milkweed is unknown; therefore, it is presumed to be 
approximately the same as the current range in southern Texas and 
northern Mexico. However, the distribution of populations throughout 
this range may have been more abundant in the past.

Regulatory and Analytical Framework

Regulatory Framework

    Section 4 of the Act (16 U.S.C. 1533) and its implementing 
regulations (50 CFR part 424) set forth the procedures for determining 
whether a species is an endangered species or a threatened species. The 
Act defines an endangered species as a species that is ``in danger of 
extinction throughout all or a significant portion of its range,'' and 
a threatened species as a species that is ``likely to become an 
endangered species within the foreseeable future throughout all or a 
significant portion of its range.'' The Act requires that we determine 
whether any species is an endangered species or a threatened species 
because of any of the following factors:

    (A) The present or threatened destruction, modification, or 
curtailment of its habitat or range;
    (B) Overutilization for commercial, recreational, scientific, or 
educational purposes;
    (C) Disease or predation;
    (D) The inadequacy of existing regulatory mechanisms; or
    (E) Other natural or manmade factors affecting its continued 
existence.

    These factors represent broad categories of natural or human-caused 
actions or conditions that could have an effect on a species' continued 
existence. In evaluating these actions and conditions, we look for 
those that may have a negative effect on individuals of the species, as 
well as other actions or conditions that may ameliorate any negative 
effects or may have positive effects.
    We use the term ``threat'' to refer in general to actions or 
conditions that are known to or are reasonably likely to negatively 
affect individuals of a species. The term ``threat'' includes actions 
or conditions that have a direct impact on individuals (direct 
impacts), as well as those that affect individuals through alteration 
of their habitat or required resources (stressors). The term ``threat'' 
may encompass--either together or separately--the source of the action 
or condition or the action or condition itself.
    However, the mere identification of any threat(s) does not 
necessarily mean that the species meets the statutory definition of an 
``endangered species'' or a ``threatened species.'' In determining 
whether a species meets either definition, we must evaluate all 
identified threats by considering the expected response by the species, 
and the effects of the threats--in light of those actions and 
conditions that will ameliorate the threats--on an individual, 
population, and species level. We evaluate each threat and its expected 
effects on the species, then analyze the cumulative effect of all of 
the threats on the species as a whole. We also consider the cumulative 
effect of the threats in light of those actions and conditions that 
will have positive effects on the species, such as any existing 
regulatory mechanisms or conservation efforts. The Secretary determines 
whether the species meets the definition of an ``endangered species'' 
or a ``threatened species'' only after conducting this cumulative 
analysis and describing the expected effect on the species now and in 
the foreseeable future.
    The Act does not define the term ``foreseeable future,'' which 
appears in the statutory definition of ``threatened species.'' Our 
implementing regulations at 50 CFR 424.11(d) set forth a framework for 
evaluating the foreseeable future on a case-by-case basis. The term 
``foreseeable future'' extends only so far into the future as the 
Service can reasonably determine that both the future threats and the 
species' responses to those threats are likely. In other words, the 
foreseeable future is the period of time in which we can make reliable 
predictions. ``Reliable'' does not mean ``certain''; it means 
sufficient to provide a reasonable degree of confidence in the 
prediction. Thus, a prediction is reliable if it is reasonable to 
depend on it when making decisions.
    It is not always possible or necessary to define foreseeable future 
as a particular number of years. Analysis of the foreseeable future 
uses the best scientific and commercial data available and should 
consider the timeframes applicable to the relevant threats and to the 
species' likely responses to those threats in view of its life-history 
characteristics. Data that are typically relevant to assessing the 
species' biological response include species-specific factors such as 
lifespan, reproductive rates or productivity, certain behaviors, and 
other demographic factors.

Analytical Framework

    The SSA report documents the results of our comprehensive 
biological review of the best scientific and commercial data regarding 
the status of the species, including an assessment of the potential 
threats to the species. The SSA report does not represent a decision by 
the Service on whether the species should be proposed for listing as an 
endangered or threatened species under the Act. However, it does 
provide the scientific basis that informs our regulatory decisions, 
which involve the further application of standards within the Act and 
its implementing regulations and policies. The following is a summary 
of the key results and conclusions from the SSA report; the full SSA 
report can be found at Docket FWS-R2-ES-2021-0041 on https://www.regulations.gov and at https://www.fws.gov/southwest/es/TexasCoastal/.
    To assess prostrate milkweed viability, we used the three 
conservation biology principles of resiliency, redundancy, and 
representation (Shaffer and Stein 2000, pp. 306-310). Briefly, 
resiliency supports the ability of the species to withstand 
environmental and demographic stochasticity (for example, wet or dry, 
warm or cold years), redundancy supports the ability of the species to 
withstand catastrophic events (for example, droughts, large pollution 
events), and representation supports the ability of the species to 
adapt over time to long-term changes in the environment (for example, 
climate changes). In general, the more resilient and redundant a 
species is and the more representation it has, the more likely it is to 
sustain populations over time, even under changing environmental 
conditions. Using these principles, we identified the species' 
ecological requirements for survival and reproduction at the 
individual, population, and species levels, and described the 
beneficial and risk factors influencing the species' viability.
    The SSA process can be categorized into three sequential stages. 
During the first stage, we evaluated the individual species' life-
history needs. The next stage involved an assessment of the historical 
and current condition of the species' demographics and habitat 
characteristics, including an explanation of how the species arrived at 
its current condition. The final stage of the SSA involved making 
predictions about the species' responses to positive and negative 
environmental and anthropogenic influences. Throughout all of these 
stages, we used the best available information to characterize 
viability as the ability of a species to

[[Page 8514]]

sustain populations in the wild over time. We use this information to 
inform our regulatory decision.

Summary of Biological Status and Threats

    In this discussion, we review the biological condition of the 
species and its resources, and the threats that influence the species' 
current and future condition, in order to assess the species' overall 
viability and the risks to that viability.
    For the prostrate milkweed to maintain viability, its populations 
or some portion thereof must have sufficient resiliency, redundancy, 
and representation. Several factors influence the resiliency of 
prostrate milkweed populations, including abundance and recruitment 
rate, in addition to elements of the species' habitat that determine 
whether prostrate milkweed populations can grow. These resiliency 
factors and habitat elements are discussed in detail in the SSA report 
and summarized here.

Species Needs

    Abundance--Prostrate milkweed abundance is difficult to assess due 
to its ability to remain dormant for multiple years until the necessary 
environmental conditions occur. Individual plants may emerge only a few 
times per decade, and not all plants will emerge at the same time 
(Price 2005, pers. comm.; Best 2017, pers. comm.). Therefore, we 
considered populations to be extant if plants have been observed within 
the past 40 years (Hammerson et al. 2008, entire; Strong 2020, pers. 
comm.) and with available habitat (i.e., not paved over) or with 
restorable habitat (i.e., nonnative grass could be removed).
    Populations of prostrate milkweed must be large enough to have a 
high probability of enduring random demographic and environmental 
variation. For example, species or populations may be classified as 
vulnerable when the probability of persisting 100 years is less than 90 
percent (Mace and Lande 1991, p. 151). This metric of population 
resilience, called minimum viable population (MVP), refers to the 
smallest population size that has a high probability of surviving over 
a specified period of time. Calculations of MVP require data that are 
not currently available for prostrate milkweed. As a practical 
alternative, we estimated the likely MVP range of prostrate milkweed by 
comparing it to species with similar life-history traits for which MVPs 
have been calculated (Pavlik 1996, p. 137). This method estimates a 
highly resilient population of prostrate milkweed has 1,600 or more 
adult individuals (Service 2020, p. 38).
    Determinations of MVP usually consider the effective population 
size, rather than total number of individuals (Pavlik 1996, entire); 10 
genetically identical individuals (for example, clones or ramets) would 
have an effective population size of one. Because prostrate milkweed is 
likely self-incompatible and does not appear to form clonal colonies, 
the effective population size is likely to be nearly the same as the 
total population size.
    Recruitment Rate--A stable or increasing population requires 
recruitment rates that equal or exceed mortality rates (Service 2020, 
p. 38). All stages of recruitment, from flowering and seed production 
to germination and establishment, occur when the soil has available 
moisture. The porous soils of prostrate milkweed habitat dry quickly 
after a single heavy thunderstorm. Based on observations of other 
perennial forbs in this ecosystem, recruitment probably occurs during 
periods of extended rainfall, meaning multiple rain events over a 
period of several weeks (Service 2020, p. 38). These events are rare in 
this semiarid region. Consequently, we expect that successful 
recruitment may occur only once or a few times per decade. Similarly, 
most mortality probably occurs during years of extended drought. Hence, 
both recruitment and mortality would have strong pulses and observed 
population sizes would vary widely from year to year, leading to 
potentially spurious interpretations of demographic trends (Service 
2020, p. 38).
    Populations of prostrate milkweed require habitats that also 
support healthy populations of large native bees and wasps (Service 
2020, p. 38). Native bees in turn require a diversity and abundance of 
native forb and shrub species that provide pollen and nectar. Tarantula 
hawks (Pepsis spp. and Hemipepsis spp.) may also be important 
pollinators of prostrate milkweed; tarantula hawks require healthy 
populations of their prey species, tarantulas (Best 2020, pers. comm.).
    Prostrate milkweed populations require competition from grasses and 
forbs to be periodically reduced (Service 2020, p. 38). This 
requirement, which has been observed in other milkweed species, may be 
an adaptation to wildfire (Baum and Sharber 2012, pp. 968-971). 
Although mowing or livestock grazing can also reduce competition, it is 
likely that prostrate milkweed is adapted to grasslands that were 
sustained by periodic wildfires (Service 2020, p. 39).
    Canopy Cover--Canopy cover refers to shade from trees, shrubs, 
prickly pear cactuses, or tall (>1 meter (m)) grass. Resilient 
prostrate milkweed populations need an open canopy with little or no 
herbaceous cover (Service 2020, p. 3). Therefore, the species may occur 
in areas that mimic historical wildfire or grazing, such as along mowed 
road rights-of-way (Service 2020, p. 3).
    Ground Cover--Ground cover refers to vegetation growing at the 
herbaceous layer (approximately <1 m) that would compete with prostrate 
milkweed plants for resources. Resilient prostrate milkweed populations 
need an open canopy with little or no herbaceous cover, so there is 
little competition with other plants (Service 2020, p. 3).

Risk Factors for Prostrate Milkweed

    We reviewed the potential risk factors (i.e., threats, stressors) 
that may affect prostrate milkweed now and in the future. In this 
proposed rule, we will discuss only those factors in detail that could 
meaningfully impact the status of the species. Those risks that are not 
known to have effects on prostrate milkweed populations, such as 
quarrying/mining, hybridization, pollinator decline, and climate 
change, are not discussed here but are evaluated in the SSA report. The 
primary risk factors (i.e., threats) affecting the status of prostrate 
milkweed are: (1) Competition from introduced invasive grasses (Factor 
A from the Act); (2) habitat loss from root-plowing and conversion of 
native vegetation to pasture (Factor A); (3) habitat loss from ROW 
construction and maintenance from energy development and road and 
utility construction (Factor A); (4) habitat loss from border security 
development and enforcement activities (Factor A); and (5) the 
demographic and genetic consequences of small population sizes and 
population fragmentation (Factor E).
Competition From Nonnative Invasive Grasses
    Nonnative invasive grass species displace native plants by 
competing for water, nutrients, and light, and their dense root systems 
prevent germination of native plant seeds (Texas Invasives 2019, 
unpaginated). Buffelgrass (Pennisetum ciliare) is a perennial 
bunchgrass introduced from Africa that is now one of the most abundant 
introduced grasses in south Texas, and the most prevalent invasive 
grass within the range of prostrate milkweed. Since the 1950s, Federal 
and State land management agencies have promoted buffelgrass as a 
forage grass in south

[[Page 8515]]

Texas (Smith 2010, p. 113). Buffelgrass is very well-adapted to the 
hot, semi-arid climate of south Texas due to its drought resistance and 
ability to aggressively establish in heavily grazed landscapes (Smith 
2010, p. 113). Buffelgrass continues to be planted in areas affected by 
drought and overgrazing to stabilize soils and to increase rangeland 
productivity. Buffelgrass often creates homogeneous monocultures by 
out-competing native plants for essential resources (Lyons et al. 2013, 
p. 8), and it produces phytotoxins in the soil that inhibit the growth 
of neighboring native plants (Vo 2013, unpaginated). Furthermore, 
prescribed burning used for brush control promotes buffelgrass forage 
production in south Texas (Hamilton and Scifres 1982, p. 11).
    Most prostrate milkweed plants have been observed where buffelgrass 
is absent or at low densities (Eason 2019, pers. comm.; Strong 2019, 
pers. comm.). On national wildlife refuge lands, prostrate milkweed was 
found in areas where native grass was still dominant, but not where 
buffelgrass or woody vegetation was present in dense stands (Best 2005, 
p. 3). The unpaved ROWs on private lands in south Texas for oil and gas 
wells, wind farms, service roads, pipelines, and powerlines could 
benefit prostrate milkweed through the periodic mowing of road margins. 
However, disturbed soils along ROWs are rapidly colonized by 
buffelgrass.
    The Texas Natural Diversity Database (TXNDD) lists invasive 
species, primarily buffelgrass, as a pervasive threat of extreme 
severity to prostrate milkweed. The TXNDD defines a pervasive threat as 
one that affects all or most (71-100 percent) of a species' 
populations, occurrences, or extent. An extreme level of severity is 
one that is likely to destroy or eliminate occurrences or habitat or 
reduce population sizes by 71-100 percent (TXNDD 2016). It is likely 
that buffelgrass has negatively impacted all Texas populations (TXNDD 
2019-2020, entire; Eason 2019, pers. comm.; Kieschnick 2019, pers. 
comm.; Santore 2019, unpaginated). Competition from buffelgrass is the 
greatest threat to prostrate milkweed.
Root-Plowing and Conversion of Native Grassland and Savanna
    Root-plowing is a brush control method that uses powerful tracked 
vehicles to excavate the roots of woody plants with heavy steel subsoil 
rippers that dig several feet into the ground. The dead trees and 
shrubs are then burned, and the root-plowed soils are planted with 
buffelgrass for livestock grazing. Root-plowing and conversion to 
buffelgrass pasture is a widely conducted practice in south Texas and 
northeast Mexico, occurring in much of the potential habitat of 
prostrate milkweed. Extensive areas of recently root-plowed lands can 
be identified in aerial photographs. These practices have been and are 
still subsidized by the United States Department of Agriculture (USDA) 
Natural Resources Conservation Service and its precursor, the USDA Soil 
Conservation Service.
    Root-plowing temporarily reduces the encroachment of woody plants 
into the grassland component of former savannas. The conversion of 
native habitats to improved pastures dominated by buffelgrass or other 
introduced grasses greatly reduces the abundance and diversity of most 
native grass and forb species (Woodin et al. 2010, p. 1). Very few, if 
any, prostrate milkweed plants survive following root-plowing and 
buffelgrass planting. This is likely due to the excavation and 
desiccation of most tubers during root-plowing; subsequently, the few 
remaining individuals decline due to competition from dense buffelgrass 
cover.
    Conversely, prostrate milkweed occurs in well-managed rangelands, 
provided that the soil was not previously root-plowed or otherwise 
disturbed (Service 2020, p. 53). Most milkweed species are unpalatable 
to cattle, and often increase in abundance on grazed lands. Livestock, 
including cattle, sheep, and horses, graze preferentially on grasses 
and forbs (broad-leaved herbaceous plants), including buffelgrass, and 
non-toxic herbaceous plants, and therefore reduce competition with 
prostrate milkweed from these plants (Service 2020, p. 41). In addition 
to grazing, livestock may also reduce competition with prostrate 
milkweed by trampling herbaceous plants (Service 2020, p. 41). Because 
prostrate milkweed is often observed in the wheel ruts of dirt roads, 
it appears to be unusually tolerant of trampling; thus, the effect of 
livestock trampling is minimal (Service 2020, pp. 41-42). Periodic 
livestock grazing reduces competition from native and introduced 
grasses. In South Texas, over-grazed rangelands typically become 
invaded by woody plants, reducing the habitat suitability for prostrate 
milkweed. Hence, management practices that promote sustainable grazing 
of native grasses are beneficial to prostrate milkweed (Service 2020, 
p. 41).
Road and ROW Construction and Maintenance
    Oil and gas exploration and wind energy development are occurring 
at a rapid pace in Starr and Zapata Counties. Seismic exploration and 
the construction of roads and caliche pads for oil and gas wells and 
wind turbines can destroy plants and their habitats within the 
construction footprint (Reemts et al. 2014, pp. 123 and 125; Leslie 
2016, p. 49). Additionally, graded service roads and other permanent 
structures may indirectly affect the hydrology of surrounding habitats 
by diverting and channeling water through drainage culverts. Invasive 
buffelgrass quickly colonizes disturbed roadsides, then invades 
adjacent habitats. Heavy vehicle traffic during oil and gas well 
drilling and wind farm construction may increase the frequency of road 
maintenance, such as grading or widening (Pe[ntilde]a 2019, pers. 
comm.). Grading or blading a caliche road involves scraping the road's 
surface with a large heavy blade to remove ruts and roadside 
vegetation. Increased frequency of road maintenance that removes above-
ground portions of plants could reduce or eliminate prostrate milkweed 
flower and fruit production. Conversely, grading or blading of caliche 
roads conducted during the milkweed's dormant periods may benefit the 
species by temporarily reducing competition from grasses and forbs 
(TXNDD 2019, p. 11). TXNDD (2019) ranks road expansion as a pervasive 
threat (affects all or most (71-100 percent) of a species' populations, 
occurrences, or extent) of extreme severity to prostrate milkweed.
    All or parts of nine prostrate milkweed occurrences are in the 
margins of improved highway ROWs. All of these highway ROW populations 
have declined since they were first observed, likely due to the 
frequency of soil disturbance and invasive grass competition (Service 
2020, p. 40). In addition, from 2010 to 2012, Texas Department of 
Transportation (TxDOT) widened segments of U.S. Highway 83 that 
affected at least three known prostrate milkweed sites: Arroyo del 
Tigre Grande, Mission Mier a Visita, and Arroyo Roma (Strong and 
Williamson 2015, p. 51; Paradise 2019, pers. comm.). TxDOT has also 
scheduled additional road widening or construction at five known 
prostrate milkweed populations: Arroyo del Tigre Grande, Arroyo del 
Tigre Chiquito, Arroyo de los Mudos, Mission Mier a Visita, and Arroyo 
Roma (TxDOT 2019, unpaginated). U.S. Customs and Border Protection 
(CBP) has scheduled road

[[Page 8516]]

improvements at the prostrate milkweed population site located in the 
Arroyo Morteros tract of the Lower Rio Grande Valley National Wildlife 
Refuge (NWR) (Vallejo 2019, pers. comm.).
    In contrast, all or parts of three prostrate milkweed occurrences 
are in the margins of unpaved rural roads. These relatively stable 
populations have persisted in narrow strips of native vegetation 
between the gravel or caliche roadbeds and the fence lines of adjacent 
private properties. The soils in these narrow, naturally vegetated 
strips have never been excavated, and they have relatively little 
buffelgrass cover.
    The installation of natural gas pipelines and fiber-optic cables 
has removed prostrate milkweed plants in the Dolores and Arroyo del 
Tigre Chiquito populations in the past (Damunde and Poole 1990, p. 32; 
Boydston 1993, unpaginated; Campos 1993, unpaginated). In 1995, 
Southwestern Bell installed a fiber-optic cable in the Highway 83 ROW, 
2.6 miles south of the Webb-Zapata County line, which removed at least 
100 individuals at the Dolores population (Service 1995, p. 1). In 
1993, prior to the fiber-optic cable installation, this population was 
estimated to have 100 to 200 individuals (TXNDD 2019, entire) and was 
the largest known population of prostrate milkweed.
    In summary, prostrate milkweed faces risks from ROWs and road 
construction and maintenance associated with oil and gas activities, 
wind energy development, and utility and pipeline corridor 
construction.

Border Security Development and Enforcement Activities

    All known Texas populations of prostrate milkweed are within 9 
miles (14.5 km) of the Texas-Mexico border. To address border security 
concerns, additional border barrier construction was proposed in the 
Rio Grande Valley, including the Arroyo Morteros tract of the Lower Rio 
Grande Valley NWR. Should border wall construction occur, and depending 
on the alignment, construction could remove prostrate milkweed plants 
that occur within the construction footprint. Additionally, CBP plans 
to improve roads across this tract (Vallejo 2019, pers. comm.) and may 
also install new drag strips along existing roads. Drag strips are 13- 
to 16-foot (ft) (4- to 5-m) -wide swaths cleared of all vegetation and 
regularly scraped to keep the soil surface loose, in order to detect 
recent foot traffic. Due to the high gypsum content, soils in this area 
are extremely vulnerable to gully erosion. Hence, the unvegetated, 
continually disturbed drag strips may exacerbate soil erosion and 
impact a much wider area. TXNDD ranks drag strip construction within 
prostrate milkweed populations as a small threat (defined as a threat 
that affects 1-10 percent of the total population or occurrences or 
extent) with an extreme level of severity (likely to destroy or 
eliminate occurrences or habitat, or reduce population by 71-100 
percent) (TXNDD 2016). Consequently, the construction of border 
barriers, roads, and drag strips are potential threats of high 
magnitude to prostrate milkweed populations, depending on their 
alignment, design, and proximity to populations and local topography.
    Native plant populations are legally protected on NWRs and, if 
listed under the Act, have additional legal protections from federally 
funded or regulated actions. However, a provision of the REAL ID Act of 
2005 gives the Secretary of Homeland Security authority to waive other 
Federal laws, including the Endangered Species Act, in order to 
expedite construction of border barriers. Therefore, border barrier 
construction on private and public lands is exempt from consultation 
with the Service under section 7 of the Act. During the previous phase 
of border barrier construction, beginning in 2007, the Department of 
Homeland Security (DHS) and the Service coordinated to establish best 
management practices for the federally listed plants and animals in the 
project impact area (DHS 2008); nevertheless, these best management 
practices did not address prostrate milkweed.

Small Population Sizes and Population Fragmentation

    Small, isolated populations are more vulnerable to catastrophic 
losses caused by random fluctuations in recruitment (demographic 
stochasticity) or variations in rainfall or other environmental factors 
(environmental stochasticity) (Service 2016, p. 20). Small, 
reproductively isolated populations are susceptible to the loss of 
genetic diversity, to genetic drift, and to inbreeding (Barrett and 
Kohn 1991, pp. 3-30). Due to the small size and isolation of prostrate 
milkweed populations, several may already suffer from genetic 
bottlenecks, genetic drift, inbreeding, and loss of allelic diversity.
    In addition to population size, it is likely that population 
density and connectivity also influence population viability (Service 
2020, p. 51). Prostrate milkweed is very likely to be an obligate 
outcrosser (fertilization between different individuals), as are most 
other Asclepias species, which requires that genetically compatible 
individuals be clustered within the forage range of the native 
pollinators for reproduction to occur (Service 2020, p. 51). While the 
specific pollinators of this species have not been revealed, they are 
likely to be large bees or wasps, and the forage range could be up to 
several kilometers. If this is the case, viable populations of 
prostrate milkweed could be dispersed at very low densities over 
relatively large areas, provided that they lie within fairly contiguous 
habitats that are traversed by pollinating insects. Thus, the small, 
isolated clusters of prostrate milkweed that have been documented, 
principally along public roads that slice through large expanses of 
potential habitat on private lands, may represent only tiny fractions 
of larger, highly dispersed populations (Service 2020, p. 51).
    Based strictly on the available scientific data, the documented 
populations of prostrate milkweed are all far below the estimated MVP 
level and may be affected by the demographic and genetic consequences 
of small population sizes and by fragmentation of populations.

Summary

    Our analysis of the past, current, and future influences on the 
needs of prostrate milkweed for long-term viability revealed several 
threats that pose a risk to current and future viability: Competition 
from introduced invasive grass (buffelgrass); root-plowing of 
rangelands; development of new oil and gas wells, wind energy farms, 
roads, pipelines, and utility corridors; development of new border 
barriers and drag strips; and the demographic and genetic consequences 
of small population sizes and population fragmentation. Conversely, 
well-managed livestock grazing of rangeland is compatible with 
management of prostrate milkweed habitat and may actually benefit this 
species.

Species Condition

    The current condition of prostrate milkweed takes into account the 
current status and risks to its populations. In the SSA report, for 
each population, we developed and assigned condition categories for two 
demographic factors and two habitat factors that are important for 
viability of prostrate milkweed. The condition scores for each factor 
were then used to estimate the probability of persistence over the next 
30 years. Populations were rated high, moderate, or low when that 
probability is greater than 90 percent, between 60 and 90 percent, or 
between 10 and 60 percent, respectively. Functionally

[[Page 8517]]

extirpated populations are not expected to persist over 30 years or are 
already extirpated.
    There are 24 populations of prostrate milkweed remaining in Starr 
and Zapata Counties, Texas, and in Tamaulipas and eastern Nuevo 
Le[oacute]n, Mexico (see Table 1, below). The species range extends 
more than 200 miles (320 kilometers) from northwest to southeast. In 
Texas, one population, Dolores, is somewhat isolated in northern Zapata 
County, with the nearest known population approximately 25 miles (40 
km) away. In Mexico, eight known populations are located in isolated 
pockets widely scattered in Tamaulipas and eastern Nuevo Le[oacute]n. 
However, botanists have only surveyed a small proportion of the 
species' range. Furthermore, the species remains dormant and 
undetectable except for short periods of time after infrequent, heavy 
rainfall. Consequently, although the species is certainly rare, its 
actual abundance is difficult to determine. It is likely that, 
historically, populations occurred between these areas, connecting the 
populations in Texas and Mexico. Because they are widely separated, 
natural gene flow or reestablishment following disturbance is very 
unlikely between the 24 known populations. Based upon our analysis of 
current conditions of these 24 extant populations, none are in high 
condition, 5 are in moderate condition, and 19 are in low condition.

      Table 1--Summary of Current Condition for Prostrate Milkweed
------------------------------------------------------------------------
             Population name                     Current  condition
------------------------------------------------------------------------
Dolores..................................  Low.
14493....................................  Low.
14491....................................  Low.
Arroyo del Tigre Grande..................  Moderate.
Arroyo del Tigre Chiquito................  Low.
FM 2098..................................  Low.
Falcon...................................  Low.
Los Alvaros..............................  Moderate.
Arroyo Morteros Tract....................  Moderate.
Los Arrieros Loop........................  Low.
Arroyo de los Mudos......................  Low.
Mission Mier a Visita....................  Low.
San Juli[aacute]n Road...................  Moderate.
FM 3167..................................  Moderate.
Arroyo Roma..............................  Low.
Arroyo Ramirez Tract.....................  Low.
Rancho La Coma...........................  Low.
Road to Guerrero Viejo...................  Low.
Carboneras...............................  Low.
Punta de Alambre.........................  Low.
Intersection of 101-180..................  Low.
Rio El Cat[aacute]n......................  Low.
Rancho Loreto North......................  Low.
Rancho Loreto South......................  Low.
------------------------------------------------------------------------

    The two demographic factors used to analyze resiliency of prostrate 
milkweed populations are abundance and recruitment rate. Related to 
abundance, a highly resilient population of prostrate milkweed has 
1,600 or more adult individuals, a moderately resilient population has 
from 800 to 1,600 mature individuals, and a population with less than 
800 mature individuals has low resilience (Service 2020, p. 38). 
Prostrate milkweed populations have high resiliency if the recruitment 
rate is greater than or equal to 25 percent of individuals producing 
viable seeds per year. Moderately resilient populations have 
recruitment rates of between 15 and 24 percent per year, and 
populations with low resiliency have recruitment rates of less than 15 
percent per year (Service 2020, p. 57).
    The two habitat factors used to analyze resiliency of prostrate 
milkweed populations were canopy cover and ground cover. Highly 
resilient populations have less than 30 percent canopy cover and have 
all bare ground or are sparsely vegetated with mostly native grass and/
or forbs. Moderately resilient populations have between 30 and 60 
percent canopy cover and are sparsely vegetated with a mixture of 
native and nonnative grasses and/or forbs. Minimally resilient 
populations have between 61 and 100 percent canopy cover and a dense 
ground cover of native or introduced grasses and forbs and little or no 
bare ground (Service 2020, p. 57).
    Redundancy is low for this species due to low numbers of 
populations in moderate to high condition for resiliency, making 
prostrate milkweed populations vulnerable to extirpations from 
catastrophic events. Because buffelgrass invasion is prevalent in this 
area, ecological diversity among the known populations is limited. 
Further, the populations are isolated and widespread across the range, 
and therefore gene flow among the populations is limited. As a 
consequence of these current conditions, the viability of the prostrate 
milkweed now primarily depends on maintaining and restoring the 
remaining isolated populations and potentially discovering or 
reintroducing new populations where feasible.
    As part of the SSA, we also developed three plausible future 
scenarios to capture the range of uncertainties regarding future 
threats and the projected responses by the prostrate milkweed. Our 
scenarios included a continuing conditions scenario, which incorporated 
the current risk factors continuing on the same trajectory that they 
are on now. We also evaluated a conservation scenario and a scenario 
with increased stressors. Because we determined that the current 
condition of the prostrate milkweed is consistent with an endangered 
species (see Determination of Species Status, below), we are not 
presenting the results of the future scenarios in this proposed rule. 
Please refer to the SSA report (Service 2020) for the full analysis of 
future scenarios.
    We note that, by using the SSA framework to guide our analysis of 
the scientific information documented in the SSA report, we have not 
only analyzed individual effects on the species, but we have also 
analyzed their potential cumulative effects. We incorporate the 
cumulative effects into our SSA analysis when we characterize the 
current and future condition of the species. To assess the current and 
future condition of the species, we undertake an iterative analysis 
that encompasses and incorporates the threats individually and then 
accumulates and evaluates the effects of all the factors that may be 
influencing the species, including threats and conservation efforts. 
Because the SSA framework considers not just the presence of the 
factors, but to what degree they collectively influence risk to the 
entire species, our assessment integrates the cumulative effects of the 
factors and replaces a standalone cumulative effects analysis.

Determination of Prostrate Milkweed Status

    Section 4 of the Act (16 U.S.C. 1533) and its implementing 
regulations (50 CFR part 424) set forth the procedures for determining 
whether a species meets the definition of an endangered species or a 
threatened species. The Act defines endangered species as a species 
``in danger of extinction throughout all or a significant portion of 
its range,'' and threatened species as a species ``likely to become an 
endangered species within the foreseeable future throughout all or a 
significant portion of its range.'' The Act requires that we determine 
whether a species meets the definition of endangered species or 
threatened species because of any of the following factors: (A) The 
present or threatened destruction, modification, or curtailment of its 
habitat or range; (B) Overutilization for commercial, recreational, 
scientific, or educational purposes; (C) Disease or predation; (D) The 
inadequacy of existing regulatory mechanisms; or (E) Other natural or 
manmade factors affecting its continued existence.

Status Throughout All of Its Range

    After evaluating threats to the species and assessing the 
cumulative effect of

[[Page 8518]]

the threats under the section 4(a)(1) factors, we found that, of the 24 
known prostrate milkweed populations remaining, 19 are small and 
isolated and are low resiliency, and five have moderate resiliency and 
connection to other populations, and none have high resiliency. Several 
factors pose a threat to prostrate milkweed, including competition from 
introduced invasive grass; habitat loss and degradations from root-
plowing and conversion of native vegetation to improved buffelgrass 
pasture; habitat loss from ROW construction and maintenance from energy 
development and road and utility construction; habitat loss from border 
security development and enforcement activities (Factor A from the 
Act); and the demographic and genetic consequences of small population 
sizes (Factor E).
    All the aforementioned threats are currently affecting the known 
populations of prostrate milkweed. Buffelgrass has already negatively 
impacted all of the Texas populations (TXNDD 2019-2020, entire; Eason 
2019, pers. comm.; Kieschnick 2019, pers. comm.; Santore 2019, 
unpaginated) and will continue to do so in the future. Habitat loss and 
degradation from root-plowing and conversion of native vegetation to 
improved buffelgrass pasture has also already been occurring for many 
years (Service 2020, p. 40). Habitat loss from ROW construction and 
maintenance from energy development and road and utility construction 
has already been observed from oil and gas development occurring in 
Zapata County. As of November 2019, no wind turbines, oil or gas well 
pads, pipelines, or energy service roads have been constructed directly 
within known prostrate milkweed populations. However, some Starr County 
prostrate milkweed populations are less than 2.0 km (1.2 mi) from 
existing wind turbines (Service 2020, pp. 42-43), and a few wind energy 
farms are expected to be constructed in the future, which could lead to 
additional habitat loss. Habitat loss from border security development 
and enforcement activities has occurred in recent years and is expected 
to continue into the future. And, finally, the demographic and genetic 
consequences of small population sizes is a current threat to the 
prostrate milkweed. This situation is not expected to change into the 
future.
    In addition to the current threats, redundancy and representation 
are also limited. There are twenty-four known populations that are 
distributed widely across its range, and the majority of those 
populations are currently in low condition. Should a catastrophic event 
occur, the populations are vulnerable to extirpation because they are 
small and isolated from each other. The small, reproductively isolated 
populations are also susceptible to the loss of genetic diversity, 
genetic drift, and inbreeding due to random fluctuations in recruitment 
(demographic stochasticity) or variations in rainfall or other 
environmental factors (environmental stochasticity). Because of the 
overall species' current resiliency, redundancy, and representation, 
prostrate milkweed is currently in danger of extinction throughout all 
of its range. We do not find the species meets the definition of a 
threatened species because the species has already shown low levels in 
current resiliency, redundancy, and representation due to the threats 
mentioned above. Thus, after assessing the best available information, 
we determine that prostrate milkweed is in danger of extinction 
throughout all of its range.

Status Throughout a Significant Portion of Its Range

    Under the Act and our implementing regulations, a species may 
warrant listing if it is in danger of extinction or likely to become so 
in the foreseeable future throughout all or a significant portion of 
its range. We have determined that the prostrate milkweed is in danger 
of extinction throughout all of its range and accordingly did not 
undertake an analysis of any significant portion of its range. Because 
the prostrate milkweed warrants listing as endangered throughout all of 
its range, our determination is consistent with the decision in Center 
for Biological Diversity v. Everson, 2020 WL 437289 (D.D.C. Jan. 28, 
2020), in which the court vacated the aspect of the Final Policy on 
Interpretation of the Phrase ``Significant Portion of Its Range'' in 
the Endangered Species Act's Definitions of ``Endangered Species'' and 
``Threatened Species'' (79 FR 37578; July 1, 2014) that provided the 
Service does not undertake an analysis of significant portions of a 
species' range if the species warrants listing as threatened throughout 
all of its range.

Determination of Status

    Our review of the best available scientific and commercial 
information indicates that the prostrate milkweed meets the definition 
of an endangered species. Therefore, we propose to list the prostrate 
milkweed as an endangered species in accordance with sections 3(20) and 
4(a)(1) of the Act.

Available Conservation Measures

    Conservation measures provided to species listed as endangered or 
threatened species under the Act include recognition, recovery actions, 
requirements for Federal protection, and prohibitions against certain 
practices. Recognition through listing results in public awareness, and 
conservation by Federal, State, Tribal, and local agencies, private 
organizations, and individuals. The Act encourages cooperation with the 
States and other countries and calls for recovery actions to be carried 
out for listed species. The protection required by Federal agencies and 
the prohibitions against certain activities are discussed, in part, 
below.
    The primary purpose of the Act is the conservation of endangered 
and threatened species and the ecosystems upon which they depend. The 
ultimate goal of such conservation efforts is the recovery of these 
listed species, so that they no longer need the protective measures of 
the Act. Section 4(f) of the Act calls for the Service to develop and 
implement recovery plans for the conservation of endangered and 
threatened species. The recovery planning process involves the 
identification of actions that are necessary to halt or reverse the 
species' decline by addressing the threats to its survival and 
recovery. The goal of this process is to restore listed species to a 
point where they are secure, self-sustaining, and functioning 
components of their ecosystems.
    Recovery planning consists of preparing draft and final recovery 
plans, beginning with the development of a recovery outline and making 
it available to the public within 30 days of a final listing 
determination. The recovery outline guides the immediate implementation 
of urgent recovery actions and describes the process to be used to 
develop a recovery plan. Revisions of the plan may be done to address 
continuing or new threats to the species, as new substantive 
information becomes available. The recovery plan also identifies 
recovery criteria for review of when a species may be ready for 
reclassification from endangered to threatened (``downlisting'') or 
removal from protected status (``delisting''), and methods for 
monitoring recovery progress. Recovery plans also establish a framework 
for agencies to coordinate their recovery efforts and provide estimates 
of the cost of implementing recovery tasks. Recovery teams (composed of 
species experts, Federal and State agencies, nongovernmental 
organizations, and stakeholders) are often established to develop 
recovery

[[Page 8519]]

plans. When completed, the recovery outline, draft recovery plan, and 
the final recovery plan will be available on our website (https://www.fws.gov/endangered), or from our Texas Coastal Ecological Services 
Field Office (see FOR FURTHER INFORMATION CONTACT).
    Implementation of recovery actions generally requires the 
participation of a broad range of partners, including other Federal 
agencies, States, Tribes, nongovernmental organizations, businesses, 
and private landowners. Examples of recovery actions include habitat 
restoration (e.g., restoration of native vegetation), research, captive 
propagation and reintroduction, and outreach and education. The 
recovery of many listed species cannot be accomplished solely on 
Federal lands because their range may occur primarily or solely on non-
Federal lands. To achieve recovery of these species requires 
cooperative conservation efforts on private, State, and Tribal lands.
    If this species is listed, funding for recovery actions will be 
available from a variety of sources, including Federal budgets, State 
programs, and cost-share grants for non-Federal landowners, the 
academic community, and nongovernmental organizations. In addition, 
pursuant to section 6 of the Act, the State of Texas would be eligible 
for Federal funds to implement management actions that promote the 
protection or recovery of the prostrate milkweed. Information on our 
grant programs that are available to aid species recovery can be found 
at: https://www.fws.gov/grants.
    Although the prostrate milkweed is only proposed for listing under 
the Act at this time, please let us know if you are interested in 
participating in recovery efforts for this species. Additionally, we 
invite you to submit any new information on this species whenever it 
becomes available and any information you may have for recovery 
planning purposes (see FOR FURTHER INFORMATION CONTACT).
    Section 7(a) of the Act requires Federal agencies to evaluate their 
actions with respect to any species that is proposed or listed as an 
endangered or threatened species and with respect to its critical 
habitat, if any is designated. Regulations implementing this 
interagency cooperation provision of the Act are codified at 50 CFR 
part 402. Section 7(a)(4) of the Act requires Federal agencies to 
confer with the Service on any action that is likely to jeopardize the 
continued existence of a species proposed for listing or result in 
destruction or adverse modification of proposed critical habitat. If a 
species is listed subsequently, section 7(a)(2) of the Act requires 
Federal agencies to ensure that activities they authorize, fund, or 
carry out are not likely to jeopardize the continued existence of the 
species or destroy or adversely modify its critical habitat. If a 
Federal action may affect a listed species or its critical habitat, the 
responsible Federal agency must enter into consultation with the 
Service.
    Federal agency actions within the species' habitat that may require 
conference or consultation or both as described in the preceding 
paragraph include management and any other landscape-altering 
activities on Federal lands administered by the U.S. Fish and Wildlife 
Service.
    The Act and its implementing regulations set forth a series of 
general prohibitions and exceptions that apply to endangered plants. 
The prohibitions of section 9(a)(2) of the Act, codified at 50 CFR 
17.61, make it illegal for any person subject to the jurisdiction of 
the United States to: Import or export; remove and reduce to possession 
from areas under Federal jurisdiction; maliciously damage or destroy on 
any such area; remove, cut, dig up, or damage or destroy on any other 
area in knowing violation of any law or regulation of any State or in 
the course of any violation of a State criminal trespass law; deliver, 
receive, carry, transport, or ship in interstate or foreign commerce, 
by any means whatsoever and in the course of a commercial activity; or 
sell or offer for sale in interstate or foreign commerce an endangered 
plant. Certain exceptions apply to employees of the Service, the 
National Marine Fisheries Service, other Federal land management 
agencies, and State conservation agencies.
    We may issue permits to carry out otherwise prohibited activities 
involving endangered plants under certain circumstances. Regulations 
governing permits are codified at 50 CFR 17.62. With regard to 
endangered plants, a permit may be issued for scientific purposes or 
for enhancing the propagation or survival of the species. The statute 
also contains certain exemptions from the prohibitions, which are found 
in sections 9 and 10 of the Act.
    It is our policy, as published in the Federal Register on July 1, 
1994 (59 FR 34272), to identify to the maximum extent practicable at 
the time a species is listed, those activities that would or would not 
constitute a violation of section 9 of the Act. The intent of this 
policy is to increase public awareness of the effect of a proposed 
listing on proposed and ongoing activities within the range of the 
species proposed for listing. Based on the best available information, 
the following actions are unlikely to result in a violation of section 
9, if these activities are carried out in accordance with existing 
regulations and permit requirements; this list is not comprehensive:
    (1) Normal agricultural and silvicultural practices, including 
herbicide and pesticide use, that are carried out in accordance with 
any existing regulations, permit and label requirements, and best 
management practices; and
    (2) Normal residential landscaping activities on non-Federal lands; 
and
    (3) Recreational use with minimal ground disturbance.
    Based on the best available information, the following activities 
may potentially result in a violation of section 9 of the Act if they 
are not authorized in accordance with applicable law; this list is not 
comprehensive:
    (1) Unauthorized handling, removing, trampling, or collecting of 
prostrate milkweed on Federal land; and
    (2) Removing, cutting, digging up, or damaging or destroying 
prostrate milkweed in knowing violation of any law or regulation of the 
State of Texas or in the course of any violation of a State criminal 
trespass law.

II. Critical Habitat

Background

    Critical habitat is defined in section 3 of the Act as:
    (1) The specific areas within the geographical area occupied by the 
species, at the time it is listed in accordance with the Act, on which 
are found those physical or biological features
    (a) Essential to the conservation of the species, and
    (b) Which may require special management considerations or 
protection; and
    (2) Specific areas outside the geographical area occupied by the 
species at the time it is listed, upon a determination that such areas 
are essential for the conservation of the species.
    Our regulations at 50 CFR 424.02 define the geographical area 
occupied by the species as an area that may generally be delineated 
around species' occurrences, as determined by the Secretary (i.e., 
range). Such areas may include those areas used throughout all or part 
of the species' life cycle, even if not used on a regular basis (e.g., 
migratory corridors, seasonal habitats, and habitats used periodically, 
but not solely by vagrant individuals).

[[Page 8520]]

Additionally, our regulations at 50 CFR 424.02 define the word 
``habitat'' as, for the purposes of designating critical habitat only, 
``the abiotic and biotic setting that currently or periodically 
contains the resources and conditions necessary to support one or more 
life processes of a species.''
    Conservation, as defined under section 3 of the Act, means to use 
and the use of all methods and procedures that are necessary to bring 
an endangered or threatened species to the point at which the measures 
provided pursuant to the Act are no longer necessary. Such methods and 
procedures include, but are not limited to, all activities associated 
with scientific resources management such as research, census, law 
enforcement, habitat acquisition and maintenance, propagation, live 
trapping, and transplantation, and, in the extraordinary case where 
population pressures within a given ecosystem cannot be otherwise 
relieved, may include regulated taking.
    Critical habitat receives protection under section 7 of the Act 
through the requirement that Federal agencies ensure, in consultation 
with the Service, that any action they authorize, fund, or carry out is 
not likely to result in the destruction or adverse modification of 
critical habitat. The designation of critical habitat does not affect 
land ownership or establish a refuge, wilderness, reserve, preserve, or 
other conservation area. Designation also does not allow the government 
or public to access private lands, nor does designation require 
implementation of restoration, recovery, or enhancement measures by 
non-Federal landowners. Where a landowner requests Federal agency 
funding or authorization for an action that may affect a listed species 
or critical habitat, the Federal agency would be required to consult 
with the Service under section 7(a)(2) of the Act. However, even if the 
Service were to conclude that the proposed activity would result in 
destruction or adverse modification of the critical habitat, the 
Federal action agency and the landowner are not required to abandon the 
proposed activity, or to restore or recover the species; instead, they 
must implement ``reasonable and prudent alternatives'' to avoid 
destruction or adverse modification of critical habitat.
    Under the first prong of the Act's definition of critical habitat, 
areas within the geographical area occupied by the species at the time 
it was listed are included in a critical habitat designation if they 
contain physical or biological features (1) which are essential to the 
conservation of the species and (2) which may require special 
management considerations or protection. For these areas, critical 
habitat designations identify, to the extent known using the best 
scientific and commercial data available, those physical or biological 
features that are essential to the conservation of the species (such as 
space, food, cover, and protected habitat). In identifying those 
physical or biological features that occur in specific occupied areas, 
we focus on the specific features that are essential to support the 
life-history needs of the species, including, but not limited to, water 
characteristics, soil type, geological features, prey, vegetation, 
symbiotic species, or other features. A feature may be a single habitat 
characteristic or a more complex combination of habitat 
characteristics. Features may include habitat characteristics that 
support ephemeral or dynamic habitat conditions. Features may also be 
expressed in terms relating to principles of conservation biology, such 
as patch size, distribution distances, and connectivity.
    Under the second prong of the Act's definition of critical habitat, 
we can designate critical habitat in areas outside the geographical 
area occupied by the species at the time it is listed, upon a 
determination that such areas are essential for the conservation of the 
species. The implementing regulations at 50 CFR 424.12(b)(2) further 
delineate unoccupied critical habitat by setting out three specific 
parameters: (1) When designating critical habitat, the Secretary will 
first evaluate areas occupied by the species; (2) the Secretary will 
only consider unoccupied areas to be essential where a critical habitat 
designation limited to geographical areas occupied by the species would 
be inadequate to ensure the conservation of the species; and (3) for an 
unoccupied area to be considered essential, the Secretary must 
determine that there is a reasonable certainty both that the area will 
contribute to the conservation of the species and that the area 
contains one or more of those physical or biological features essential 
to the conservation of the species.
    Section 4 of the Act requires that we designate critical habitat on 
the basis of the best scientific data available. Further, our Policy on 
Information Standards Under the Endangered Species Act (published in 
the Federal Register on July 1, 1994 (59 FR 34271)), the Information 
Quality Act (section 515 of the Treasury and General Government 
Appropriations Act for Fiscal Year 2001 (Pub. L. 106-554; H.R. 5658)), 
and our associated Information Quality Guidelines provide criteria, 
establish procedures, and provide guidance to ensure that our decisions 
are based on the best scientific data available. They require our 
biologists, to the extent consistent with the Act and with the use of 
the best scientific data available, to use primary and original sources 
of information as the basis for recommendations to designate critical 
habitat.
    When we are determining which areas should be designated as 
critical habitat, our primary source of information is generally the 
information from the SSA report and information developed during the 
listing process for the species. Additional information sources may 
include any generalized conservation strategy, criteria, or outline 
that may have been developed for the species; the recovery plan for the 
species; articles in peer-reviewed journals; conservation plans 
developed by States and counties; scientific status surveys and 
studies; biological assessments; other unpublished materials; or 
experts' opinions or personal knowledge.
    As the regulatory definition of ``habitat'' reflects (50 CFR 
424.02), habitat is dynamic, and species may move from one area to 
another over time. We recognize that critical habitat designated at a 
particular point in time may not include all of the habitat areas that 
we may later determine are necessary for the recovery of the species. 
For these reasons, a critical habitat designation does not signal that 
habitat outside the designated area is unimportant or may not be needed 
for recovery of the species. Areas that are important to the 
conservation of the species, both inside and outside the critical 
habitat designation, will continue to be subject to: (1) Conservation 
actions implemented under section 7(a)(1) of the Act; (2) regulatory 
protections afforded by the requirement in section 7(a)(2) of the Act 
for Federal agencies to ensure their actions are not likely to 
jeopardize the continued existence of any endangered or threatened 
species; and (3) the prohibitions found in section 9 of the Act. 
Federally funded or permitted projects affecting listed species outside 
their designated critical habitat areas may still result in jeopardy 
findings in some cases. These protections and conservation tools will 
continue to contribute to recovery of the species. Similarly, critical 
habitat designations made on the basis of the best available 
information at the time of designation will not control the direction 
and substance of future recovery plans, habitat conservation plans 
(HCPs), or other species conservation planning

[[Page 8521]]

efforts if new information available at the time of those planning 
efforts calls for a different outcome.

Prudency Determination

    Section 4(a)(3) of the Act, as amended, and implementing 
regulations (50 CFR 424.12) require that, to the maximum extent prudent 
and determinable, the Secretary shall designate critical habitat at the 
time the species is determined to be an endangered or threatened 
species. Our regulations (50 CFR 424.12(a)(1)) state that the Secretary 
may, but is not required to, determine that a designation would not be 
prudent in the following circumstances:
    (i) The species is threatened by taking or other human activity and 
identification of critical habitat can be expected to increase the 
degree of such threat to the species;
    (ii) The present or threatened destruction, modification, or 
curtailment of a species' habitat or range is not a threat to the 
species, or threats to the species' habitat stem solely from causes 
that cannot be addressed through management actions resulting from 
consultations under section 7(a)(2) of the Act;
    (iii) Areas within the jurisdiction of the United States provide no 
more than negligible conservation value, if any, for a species 
occurring primarily outside the jurisdiction of the United States;
    (iv) No areas meet the definition of critical habitat; or
    (v) The Secretary otherwise determines that designation of critical 
habitat would not be prudent based on the best scientific data 
available.
    As discussed earlier in this document, there is currently no 
imminent threat of collection or vandalism identified under Factor B 
for this species, and identification and mapping of critical habitat is 
not expected to initiate any such threat. In our SSA and proposed 
listing determination for prostrate milkweed, we determined that the 
present or threatened destruction, modification, or curtailment of 
habitat or range is a threat to prostrate milkweed and that those 
threats in some way can be addressed by section 7(a)(2) consultation 
measures. We are able to identify areas that meet the definition of 
critical habitat where the species occurs in the United States. 
Therefore, because none of the circumstances enumerated in our 
regulations at 50 CFR 424.12(a)(1) have been met and because the 
Secretary has not identified other circumstances for which this 
designation of critical habitat would not be prudent, we have 
determined that the designation of critical habitat is prudent for 
prostrate milkweed.

Critical Habitat Determinability

    Having determined that designation is prudent, under section 
4(a)(3) of the Act we must find whether critical habitat for the 
prostrate milkweed is determinable. Our regulations at 50 CFR 
424.12(a)(2) state that critical habitat is not determinable when one 
or both of the following situations exist:
    (i) Data sufficient to perform required analyses are lacking, or
    (ii) The biological needs of the species are not sufficiently well 
known to identify any area that meets the definition of ``critical 
habitat.''
    When critical habitat is not determinable, the Act allows the 
Service an additional year to publish a critical habitat designation 
(16 U.S.C. 1533(b)(6)(C)(ii)).
    We reviewed the available information pertaining to the biological 
needs of the species and habitat characteristics where this species is 
located. This and other information represent the best scientific data 
available and led us to conclude that the designation of critical 
habitat is determinable for the prostrate milkweed.

Physical or Biological Features Essential to the Conservation of the 
Species

    In accordance with section 3(5)(A)(i) of the Act and regulations at 
50 CFR 424.12(b), in determining which areas we will designate as 
critical habitat from within the geographical area occupied by the 
species at the time of listing, we consider the physical or biological 
features (PBFs) that are essential to the conservation of the species 
and that may require special management considerations or protection. 
The regulations at 50 CFR 424.02 define ``physical or biological 
features essential to the conservation of the species'' as the features 
that occur in specific areas and that are essential to support the 
life-history needs of the species, including, but not limited to, water 
characteristics, soil type, geological features, sites, prey, 
vegetation, symbiotic species, or other features. A feature may be a 
single habitat characteristic or a more complex combination of habitat 
characteristics. Features may include habitat characteristics that 
support ephemeral or dynamic habitat conditions. Features may also be 
expressed in terms relating to principles of conservation biology, such 
as patch size, distribution distances, and connectivity. For example, 
physical features essential to the conservation of the species might 
include gravel of a particular size required for spawning, alkaline 
soil for seed germination, protective cover for migration, or 
susceptibility to flooding or fire that maintains necessary early-
successional habitat characteristics. Biological features might include 
prey species, forage grasses, specific kinds or ages of trees for 
roosting or nesting, symbiotic fungi, or a particular level of 
nonnative species consistent with conservation needs of the listed 
species. The features may also be combinations of habitat 
characteristics and may encompass the relationship between 
characteristics or the necessary amount of a characteristic essential 
to support the life history of the species.
    In considering whether features are essential to the conservation 
of the species, we may consider an appropriate quality, quantity, and 
spatial and temporal arrangement of habitat characteristics in the 
context of the life-history needs, condition, and status of the 
species. These characteristics include, but are not limited to, space 
for individual and population growth and for normal behavior; food, 
water, air, light, minerals, or other nutritional or physiological 
requirements; cover or shelter; sites for breeding, reproduction, or 
rearing (or development) of offspring; and habitats that are protected 
from disturbance.

Geological Substrate and Soils

    Prostrate milkweed grows in well-drained sandy soils of the 
Tamaulipan shrubland region of south Texas and northeast Mexico 
(Service 2020, pp. 22-26). In Starr and Zapata Counties, Texas, the 
soils of documented sites overlie Eocene and Oligocene sandstones and 
clays of the Laredo, Yegua, and Jackson geological formations (Stoeser 
et al. 2005). In some occupied sites, a stratum of indurated caliche 
may also be present; in south Texas, caliche refers to soil strata of 
precipitated calcium carbonate formed during the early Pliocene 
(Spearing 1998, pp. 258, 398; Baskin and Hulbert, Jr. 2008, p. 93). 
Soil types of these occupied sites include deep eolian Hebbronville 
sands, Copita fine sandy loam, Brennan fine sandy loam, eroded Maverick 
soils, Catarina clay, and Zapata soils (USDA 1972; USDA 2011). Elevated 
levels of gypsum are present at some sites.
    The climate of the Tamaulipan shrubland region is subtropical and 
semi-arid. Much of the region's precipitation occurs during infrequent 
periods of heavy rainfall that interrupt prolonged spells of very hot, 
dry weather. Rainfall readily infiltrates into the well-drained sandy 
soils of prostrate milkweed habitats, but moisture does

[[Page 8522]]

not persist long in these soils. Many occupied sites have underlying 
strata of sandstone; these barriers to root growth limit the 
establishment of trees and taller shrubs. The growth of many plant 
species is also limited by high soil gypsum concentrations in some 
occupied sites. The rapid drying of soil, impenetrable rock strata, and 
high gypsum are all factors that reduce competition from woody plants, 
grasses, and other herbaceous plants.
    Prostrate milkweed forms tubers underground that are able to 
persist in a dormant condition for one to several years. The species 
responds very quickly to rainfall; the tubers sprout new stems that 
emerge, flower, and set seed in a matter of weeks, and the plants store 
carbohydrates, minerals, and water in tubers. Then the above-ground 
portions die back during hot, dry weather. Prostrate milkweed does not 
occur in areas of higher rainfall or where moisture persists longer in 
deeper silty or clayey soils. The species does not persist when 
occupied sites develop a dense shrub overstory or dense cover of 
grasses. We conclude that prostrate milkweed is endemic to sites where 
it escapes competition from other plants through its unique adaptation 
to ephemeral soil moisture, prolonged drought, and tolerance of high 
gypsum concentrations.
    Therefore, well-drained sandy soil overlying sandstone or indurated 
caliche strata is an essential physical feature of prostrate milkweed 
critical habitats. A high soil gypsum concentration contributes to the 
habitat suitability of some sites by reducing competition, and is an 
essential physical feature.

Ecological Community

    Within the Tamaulipan shrubland ecological region, prostrate 
milkweed inhabits arid subtropical grasslands and shrub savannas. It 
requires an open canopy, where there is little or no shade from trees 
and shrubs, and relatively little competition from grasses and 
herbaceous plants; the estimated combined cover of woody plants, 
grasses, and herbaceous plants at a site in Zapata County was less than 
30 percent (Damude and Poole 1990, p. 16). It is likely that naturally 
occurring wildfires, in the past, maintained the relatively open 
structure of these plant communities (Scifres and Hamilton 1993, pp. 8-
21). We have observed an increased abundance of other Texas species of 
Asclepias, including antelope horns (A. asperula), Emory's milkweed (A. 
emoryi), zizotes milkweed (A. oenotheroides), and wand milkweed (A. 
viridiflora), during the first few years after sites have burned; this 
fire-following effect has been described for green milkweed (A. 
viridis) (Baum and Sharber 2012, entire). Prostrate milkweed, like 
other milkweeds, may also be stimulated to grow and flower after 
wildfires have reduced competition.
    Most Asclepias species require outcrossing for effective 
fertilization of flowers. All Asclepias species have highly specialized 
pollination mechanisms that require animal pollinators to carry pollen 
from one individual to another. Although the effective pollinators of 
prostrate milkweed have not been determined, these are likely to 
include large bees and wasps. For example, the closely related zizotes 
milkweed is effectively pollinated by very large wasps called tarantula 
hawks (Pepsis spp. and Hemipepsis spp.) (Service 2020, pp. 17, 35-36). 
Therefore, prostrate milkweed habitats must also support populations of 
large bees and wasps that, in turn, require abundant, diverse sources 
of pollen and nectar. Much like milkweeds, many pollen and nectar 
plants are fire followers that are most abundant in sites that burn 
periodically, but decline when fires are infrequent.
    Buffelgrass is an African grass that is widely planted in south 
Texas for livestock forage. Buffelgrass is highly invasive, and 
frequently displaces native grasses and herbaceous plants (Best 2009, 
pp. 310-311), including prostrate milkweed (Service 2020, pp. 39-40) 
and the pollen and nectar plants needed to support pollinator 
populations. The majority of prostrate milkweed plants have been 
observed in disturbed soils where buffelgrass is absent or at low 
densities (Eason 2019, pers. comm.; Strong 2019, pers. comm.). 
Prostrate milkweed requires an open canopy with less than 30 percent 
cover of native and nonnative grasses and herbaceous plants combined 
(Damude and Poole 1990, p. 16); so, assuming nonnative buffelgrass is 
more prevalent, we estimate that 20 percent or less cover of 
buffelgrass is at a low enough density for prostrate milkweed to 
survive. Therefore, prostrated milkweed habitats must also have less 
than 20 percent cover of buffelgrass for prostrate milkweed to have 
access to sufficient resources such as sunlight.
    In summary, the essential biological features of prostrate milkweed 
critical habitats are: (1) Open savannas and grasslands of the 
Tamaulipan shrubland ecological region; (2) vegetation composition that 
includes abundant, diverse pollen and nectar plants and healthy 
populations of native bee and wasp species; and (3) less than 20 
percent cover of buffelgrass. Periodic prescribed burning may be 
necessary to maintain the open structure and diverse composition of the 
species' habitats.

Summary of Essential Physical or Biological Features

    Additional information can be found in the SSA report (Service 
2020, available on https://www.regulations.gov under Docket No. FWS-R2-
ES-2021-0041). We have determined that the following physical or 
biological features are essential to the conservation of prostrate 
milkweed:
    (1) Well-drained sandy soil overlying strata of sandstone or 
indurated caliche;
    (2) High soil gypsum concentration;
    (3) Open savannas and grasslands of the Tamaulipan shrubland 
ecological region;
    (4) Vegetation composition that includes abundant, diverse pollen 
and nectar plants and healthy populations of native bee and wasp 
species; and
    (5) Less than 20 percent cover of buffelgrass.

Special Management Considerations or Protection

    When designating critical habitat, we assess whether the specific 
areas within the geographical area occupied by the species at the time 
of listing contain features that are essential to the conservation of 
the species and which may require special management considerations or 
protection. The features essential to the conservation of this species 
may require special management considerations or protection to reduce 
the following threats: Nonnative invasive grass; root-plowing and 
conversion of native vegetation to buffelgrass pasture; ROW 
construction and maintenance from energy development and road and 
utility construction; border security development and law enforcement 
activities; and small population sizes. Management activities that 
could ameliorate these threats include, but are not limited to: 
Prescribed burning, grazing, and/or brush thinning; nonnative invasive 
grass control; protection from activities that disturb the soil; and 
propagation and reintroduction of plants in restorable areas.
    In summary, we find that the occupied areas we are proposing to 
designate as critical habitat contain the PBFs that are essential to 
the conservation of the species and that may require special management 
considerations or protection. Special management considerations or 
protection may be required of the Federal action agency to eliminate, 
or to

[[Page 8523]]

reduce to negligible levels, the threats affecting the PBFs of each 
unit.

Criteria Used To Identify Critical Habitat

    As required by section 4(b)(2) of the Act, we use the best 
scientific data available to designate critical habitat. In accordance 
with the Act and our implementing regulations at 50 CFR 424.12(b), we 
review available information pertaining to the habitat requirements of 
the species and identify specific areas within the geographical area 
occupied by the species at the time of listing and any specific areas 
outside the geographical area occupied by the species to be considered 
for designation as critical habitat. We are not currently proposing to 
designate any areas outside the geographical area occupied by the 
species because we have not identified any unoccupied areas that meet 
the definition of critical habitat. While prostrate milkweed needs 
additional populations to reduce the likelihood of extinction in the 
future, we are not able to identify additional locations that may have 
a reasonable certainty of contributing to conservation at this time due 
to limited access to privately owned lands and information regarding 
lands that would be good candidates for introductions in the species' 
range.
    In summary, for areas within the geographic area occupied by the 
species at the time of listing, we delineated critical habitat unit 
boundaries using the following criteria. First, using ArcGIS software, 
we identified potential habitats in Starr and Zapata Counties that have 
the essential features of geology and soils described above. The 
geographic information we obtained about the known populations exists 
as: (1) Vegetation surveys of entire tracts of land; (2) Element 
Occurrence (EO) polygons represented in the TXNDD; or (3) points and 
lines represented in the TXNDD. We then adapted methods to delineate 
critical habitats for each type of geographic information.
    We delineated all of the potential habitats that occur at the 
Arroyo Ramirez tract and the Arroyo Morteros tract of the Lower Rio 
Grande Valley NWR as proposed critical habitat (Units 2 and 5). The 
Lower Rio Grande Valley NWR comprises several disconnected land 
parcels, rather than one big land area, and these parcels are referred 
to as ``tracts.'' The two tracts that are included in proposed Units 2 
and 5 are isolated areas of refuge land. These NWR tracts are managed 
for the conservation of native plants and animals, and we have 
conducted plant surveys and have extensive knowledge of habitat 
suitability of these tracts.
    Similarly, we delineated all of the potential habitats that occur 
at a private ranch (Unit 6) that is managed for wildlife and plant 
conservation as proposed critical habitat. The landowner has granted 
access for plant surveys and vegetation studies to researchers from the 
Texas Parks and Wildlife Department, academic institutions, and the 
Service. Two of the known populations are represented as polygons in 
the TXNDD located in the ROWs of unpaved county roads in Starr County. 
We have no information about the land uses or habitat suitability of 
areas outside these polygons. We delineated all of the potential 
habitats that occur within these polygons (Units 4 and 7) as proposed 
critical habitat. Three of the known populations are represented as one 
or more points or lines in the TXNDD located on privately owned land. 
We have no information about the land uses or habitat suitability of 
areas outside the points and lines. Because critical habitats must be 
areas, not points or lines, we delineated all areas of potential 
habitat within a buffer of 50 m (164 ft) from these points and lines as 
proposed critical habitat units; we chose the 50-m distance because the 
TXNDD also used a 50-m buffer for most of these features to account for 
estimated geographic precision. To complete the delineations of 
critical habitat areas, we overlaid each critical habitat area 
described above on Digital Ortho-Quarter Quad aerial photographs to 
identify and exclude any portions of sites that consisted of 
unvegetated road beds that are frequently driven and are maintained by 
road grading, as well as structures and other developed areas that did 
not contain the geological and soil substrates and vegetative cover 
that are essential physical and biological features.
    We did not include one historical observation that has only 
approximate location data and cannot be mapped. We also did not include 
any of the populations reported in the U.S. Highway 83 ROW, all of 
which have declined since they were first reported. For example, part 
of EO 3 (Dolores) along U.S. 83 had about 200 individuals in 1988; four 
surveys conducted from 2009 to 2017 found from 0 to 3 individuals. The 
degree and frequency of soil disturbance in the ROWs of improved 
highways has caused almost complete replacement of the native plant 
community with introduced species, such as buffelgrass. Hence, the 
essential physical and biological features are no longer present along 
this improved highway ROW. For the same reasons, we did not include one 
site in the road bed of a Starr County park where the species was last 
observed in 1995.
    The scale of the maps we prepared under the parameters for 
publication within the Code of Federal Regulations may not reflect the 
exclusion of such developed lands. Any such lands inadvertently left 
inside critical habitat boundaries shown on the maps of this proposed 
rule have been excluded by text in the proposed rule and are not 
proposed for designation as critical habitat. Therefore, if the 
critical habitat is finalized as proposed, a Federal action involving 
these lands would not trigger section 7 consultation with respect to 
critical habitat and the requirement of no adverse modification unless 
the specific action would affect the physical or biological features in 
the adjacent critical habitat.
    We propose to designate as critical habitat lands that we have 
determined are occupied at the time of listing (i.e., currently 
occupied) and that contain one or more of the physical or biological 
features that are essential to support life-history processes of the 
species.
    Units are proposed for designation based on one or more of the 
physical or biological features being present to support prostrate 
milkweed's life-history processes. Some units contain all of the 
identified physical or biological features and support multiple life-
history processes. Some units contain only some of the physical or 
biological features necessary to support the prostrate milkweed's 
particular use of that habitat.
    The proposed critical habitat designation is defined by the map or 
maps, as modified by any accompanying regulatory text, presented at the 
end of this document under Proposed Regulation Promulgation. We include 
more detailed information on the boundaries of the critical habitat 
designation in the preamble of this document. We will make the 
coordinates or plot points or both on which each map is based available 
to the public on https://www.regulations.gov at Docket No. FWS-R2-ES-
2021-0041 and on our internet site https://www.fws.gov/southwest/es/TexasCoastal/.

Proposed Critical Habitat Designation

    We are proposing eight units as critical habitat for prostrate 
milkweed. The critical habitat areas we describe below constitute our 
current best assessment of areas that meet the definition of critical 
habitat for prostrate milkweed. The eight areas we propose as critical 
habitat units are all TXNDD EOs: Unit 1 (EO 3), Unit 2 (EO 10), Unit

[[Page 8524]]

3 (EO 11), Unit 4 (EO 12), Unit 5 (EO 15), Unit 6 (EO 16), Unit 7 (EO 
17), and Unit 8 (EO 22). Table 2 shows the proposed critical habitat 
units and the approximate area of each unit. All units are occupied.

                         Table 2--Proposed Critical Habitat Units for Prostrate Milkweed
                    [Area estimates reflect all land within critical habitat unit boundaries]
----------------------------------------------------------------------------------------------------------------
                                                                       Size of unit
          Critical habitat unit             Land ownership by type       in acres              Occupied?
                                                                        (hectares)
----------------------------------------------------------------------------------------------------------------
1 (EO 3)................................  County Road ROW and           10.51 (4.25)  Yes.
                                           Private.
2 (EO 10)...............................  Federal--Service..........  105.43 (42.67)  Yes.
3 (EO 11)...............................  Private...................      4.0 (1.62)  Yes.
4 (EO 12)...............................  County Road ROW...........       4.2 (1.7)  Yes.
5 (EO 15)...............................  Federal--Service..........   62.49 (25.29)  Yes.
6 (EO 16)...............................  County Road ROW and         484.32 (196.0)  Yes.
                                           Private.
7 (EO 17)...............................  County Road ROW and           19.35 (7.83)  Yes.
                                           Private.
8 (EO 22)...............................  Private...................     1.04 (0.42)  Yes.
                                         -----------------------------------------------------------------------
    Total...............................  ..........................   691.3 (279.8)
----------------------------------------------------------------------------------------------------------------
Note: Area sizes may not sum due to rounding.

    We present brief descriptions of all units, and reasons why they 
meet the definition of critical habitat for prostrate milkweed below.

Unit 1: EO 3

    Unit 1 consists of six areas, totaling 10.51 ac (4.25 ha), east of 
highway 83 in northwest Zapata County. This unit is on private land and 
unpaved county road ROWs. The unit is occupied by the species and 
contains one or more of the PBFs essential to the conservation of 
prostrate milkweed. Although we have no recent information on threats 
that affect this unit, we conclude that this unit is affected by 
invasive nonnative grass (buffelgrass) and road maintenance operations. 
Therefore, special management considerations may be required to reduce 
invasion of nonnative species and impacts from ROW maintenance.

Unit 2: EO 10

    Unit 2 consists of 105.43 ac (42.67 ha) in the 699.4-acre Arroyo 
Ramirez tract of Lower Rio Grande Valley NWR. This unit is in 
southwestern Starr County adjacent to the Rio Grande on the U.S.-Mexico 
border. The entire unit is on land owned and managed by the Service. 
The unit is occupied by the species and contains one or more of the 
PBFs essential to the conservation of prostrate milkweed. This unit 
could be directly impacted by border barrier construction and security 
operations (i.e., drag strips), or indirectly impacted by channeling of 
runoff along the barrier during heavy rainfall, in addition to invasion 
of buffelgrass. Therefore, special management may be required to 
mitigate impacts from border security operations and nonnative grass.

Unit 3: EO 11

    Unit 3 consists of three areas, totaling 4.0 ac (1.62 ha), on 
private land in southwestern Starr County. The unit is occupied by the 
species and contains one or more of the PBFs essential to the 
conservation of prostrate milkweed. We have no recent information on 
threats that affect this unit.

Unit 4: EO 12

    Unit 4 consists of 4.2 ac (1.7 ha) along an unpaved county road ROW 
in southwestern Starr County. This ROW supports a narrow strip of 
diverse native vegetation that has likely not been plowed, bulldozed, 
or graded. The unit is occupied by the species and contains one or more 
of the PBFs essential to the conservation of prostrate milkweed. This 
unit is affected by invasive nonnative grass (buffelgrass) and 
maintenance and operation of the county road. Therefore, special 
management may be required to reduce invasion of nonnative species.

Unit 5: EO 15

    Unit 5 consists of 62.49 ac (25.29 ha) in the 90.8-acre Arroyo 
Morteros tract of the Lower Rio Grande Valley NWR. This unit is in 
southwestern Starr County adjacent to the Rio Grande on the U.S.-Mexico 
border. The entire unit is on land owned and managed by the Service. 
The unit is occupied by the species and contains one or more of the 
PBFs essential to the conservation of prostrate milkweed. This unit 
could be directly impacted by border barrier construction and security 
operations (i.e., drag strips), or indirectly impacted by channeling of 
runoff along the barrier during heavy rainfall, in addition to invasion 
of buffelgrass. Therefore, special management may be required to 
mitigate impacts from border security operations and nonnative grass.

Unit 6: EO 16

    Unit 6 consists of 484.32 ac (196.0 ha) entirely on the 488.5-acre 
private Martinez Ranch and along a county road ROW. This unit is in 
southern Starr County. The owner of the Martinez Ranch is a willing 
conservation partner in managing the property's native plants and 
wildlife. The unit is occupied by the species and contains one or more 
of the PBFs essential to the conservation of prostrate milkweed. This 
unit is affected by invasive nonnative grass (buffelgrass). Therefore, 
special management may be required to reduce invasion of nonnative 
species.

Unit 7: EO 17

    Unit 7 consists of 19.35 ac (7.83 ha) along both sides of an 
unpaved county road ROW and adjacent private land in western Starr 
County. This ROW supports a narrow strip of diverse native vegetation 
that has likely not been plowed, bulldozed, or graded. The unit is 
occupied by the species and contains one or more of the PBFs essential 
to the conservation of prostrate milkweed. This unit is affected by 
invasive nonnative grass (buffelgrass) and maintenance and operation of 
the county road. Therefore, special management may be required to 
reduce invasion of nonnative species.

Unit 8: EO 22

    Unit 8 consists of 1.04 ac (0.42 ha) on private land in central 
Zapata County. The unit is occupied by the species and contains one or 
more of the PBFs essential to the conservation of prostrate milkweed. 
Although we have no recent information about threats that affect this 
unit, we estimate that this unit is

[[Page 8525]]

affected by invasive nonnative grass (buffelgrass) and development and 
maintenance of oil and gas wells and utility corridors. Therefore, 
special management may be required to reduce invasion of nonnative 
species and impacts from ROW construction and maintenance from energy 
development and road and utility construction.

Effects of Critical Habitat Designation

Section 7 Consultation

    Section 7(a)(2) of the Act requires Federal agencies, including the 
Service, to ensure that any action they fund, authorize, or carry out 
is not likely to jeopardize the continued existence of any endangered 
species or threatened species or result in the destruction or adverse 
modification of designated critical habitat of such species. In 
addition, section 7(a)(4) of the Act requires Federal agencies to 
confer with the Service on any agency action that is likely to 
jeopardize the continued existence of any species proposed to be listed 
under the Act or result in the destruction or adverse modification of 
proposed critical habitat.
    We published a final rule revising the definition of destruction or 
adverse modification on August 27, 2019 (84 FR 44976). Destruction or 
adverse modification means a direct or indirect alteration that 
appreciably diminishes the value of critical habitat as a whole for the 
conservation of a listed species.
    If a Federal action may affect a listed species or its critical 
habitat, the responsible Federal agency (action agency) must enter into 
consultation with us. Examples of actions that are subject to the 
section 7 consultation process are actions on State, Tribal, local, or 
private lands that require a Federal permit (such as a permit from the 
U.S. Army Corps of Engineers under section 404 of the Clean Water Act 
(33 U.S.C. 1251 et seq.) or a permit from the Service under section 10 
of the Act) or that involve some other Federal action (such as funding 
from the Federal Highway Administration, Federal Aviation 
Administration, or the Federal Emergency Management Agency). Federal 
actions not affecting listed species or critical habitat--and actions 
on State, Tribal, local, or private lands that are not federally 
funded, authorized, or carried out by a Federal agency--do not require 
section 7 consultation.
    Compliance with the requirements of section 7(a)(2) is documented 
through our issuance of:
    (1) A concurrence letter for Federal actions that may affect, but 
are not likely to adversely affect, listed species or critical habitat; 
or
    (2) A biological opinion for Federal actions that may affect, and 
are likely to adversely affect, listed species or critical habitat.
    When we issue a biological opinion concluding that a project is 
likely to jeopardize the continued existence of a listed species and/or 
destroy or adversely modify critical habitat, we provide reasonable and 
prudent alternatives to the project, if any are identifiable, that 
would avoid the likelihood of jeopardy and/or destruction or adverse 
modification of critical habitat. We define ``reasonable and prudent 
alternatives'' (at 50 CFR 402.02) as alternative actions identified 
during consultation that:
    (1) Can be implemented in a manner consistent with the intended 
purpose of the action,
    (2) Can be implemented consistent with the scope of the Federal 
agency's legal authority and jurisdiction,
    (3) Are economically and technologically feasible, and
    (4) Would, in the Service Director's opinion, avoid the likelihood 
of jeopardizing the continued existence of the listed species and/or 
avoid the likelihood of destroying or adversely modifying critical 
habitat.
    Reasonable and prudent alternatives can vary from slight project 
modifications to extensive redesign or relocation of the project. Costs 
associated with implementing a reasonable and prudent alternative are 
similarly variable.
    Regulations at 50 CFR 402.16 set forth requirements for Federal 
agencies to reinitiate formal consultation on previously reviewed 
actions. These requirements apply when the Federal agency has retained 
discretionary involvement or control over the action (or the agency's 
discretionary involvement or control is authorized by law) and, if 
subsequent to the previous consultation: (1) If the amount or extent of 
taking specified in the incidental take statement is exceeded; (2) if 
new information reveals effects of the action that may affect listed 
species or critical habitat in a manner or to an extent not previously 
considered; (3) if the identified action is subsequently modified in a 
manner that causes an effect to the listed species or critical habitat 
that was not considered in the biological opinion; or (4) if a new 
species is listed or critical habitat designated that may be affected 
by the identified action. In such situations, Federal agencies 
sometimes may need to request reinitiation of consultation with us, but 
the regulations also specify some exceptions to the requirement to 
reinitiate consultation on specific land management plans after 
subsequently listing a new species or designating new critical habitat. 
See the regulations for a description of those exceptions.

Application of the ``Destruction or Adverse Modification'' Standard

    The key factor related to the destruction or adverse modification 
determination is whether implementation of the proposed Federal action 
directly or indirectly alters the designated critical habitat in a way 
that appreciably diminishes the value of the critical habitat as a 
whole for the conservation of the listed species. As discussed above, 
the role of critical habitat is to support physical or biological 
features essential to the conservation of a listed species and provide 
for the conservation of the species.
    Section 4(b)(8) of the Act requires us to briefly evaluate and 
describe, in any proposed or final regulation that designates critical 
habitat, activities involving a Federal action that may violate section 
7(a)(2) of the Act by destroying or adversely modifying such habitat, 
or that may be affected by such designation.
    Activities that the Service may, during a consultation under 
section 7(a)(2) of the Act, be considered likely to destroy or 
adversely modify critical habitat include, but are not limited to:
    (1) Actions that would degrade or destroy native plant communities. 
Such activities could include, but are not limited to, road building, 
land clearing for oil and gas exploration or other purposes, 
introducing and encouraging the spread of nonnative species (i.e., 
buffelgrass), and border security operations. However, above-ground 
cutting or thinning of woody plants and prescribed burning are 
recommended management practices for conservation of prostrate milkweed 
and other native grasses and forbs, and would not destroy or adversely 
modify critical habitats.
    (2) Actions that would mechanically disturb the soil structure. 
Such activities could include, but are not limited to, bulldozing, 
root-plowing, ripping, excavating, or other mechanical operations that 
penetrate deep enough into the soil to cut or remove the tubers of 
prostrate milkweed.
    (3) Actions that would increase competition from woody plants or 
introduced grasses. Such activities could include, but are not limited 
to, intentional planting of introduced grass species, such as 
buffelgrass, bermudagrass (Cynodon dactylon), or

[[Page 8526]]

Old World bluestems (introduced species of Dichanthium and 
Bothriochloa).

Exemptions

Application of Section 4(a)(3) of the Act

    Section 4(a)(3)(B)(i) of the Act (16 U.S.C. 1533(a)(3)(B)(i)) 
provides that the Secretary shall not designate as critical habitat any 
lands or other geographical areas owned or controlled by the Department 
of Defense (DoD), or designated for its use, that are subject to an 
integrated natural resources management plan (INRMP) prepared under 
section 101 of the Sikes Act (16 U.S.C. 670a), if the Secretary 
determines in writing that such plan provides a benefit to the species 
for which critical habitat is proposed for designation. No DoD lands 
with a completed INRMP are within the proposed critical habitat 
designation.

Consideration of Impacts Under Section 4(b)(2) of the Act

    Section 4(b)(2) of the Act states that the Secretary shall 
designate and make revisions to critical habitat on the basis of the 
best available scientific data after taking into consideration the 
economic impact, national security impact, and any other relevant 
impact of specifying any particular area as critical habitat. The 
Secretary may exclude an area from critical habitat if she determines 
that the benefits of such exclusion outweigh the benefits of specifying 
such area as part of the critical habitat, unless she determines, based 
on the best scientific data available, that the failure to designate 
such area as critical habitat will result in the extinction of the 
species. In making the determination to exclude a particular area, the 
statute on its face, as well as the legislative history, are clear that 
the Secretary has broad discretion regarding which factor(s) to use and 
how much weight to give to any factor.
    Under section 4(b)(2) of the Act, we may exclude an area from 
designated critical habitat based on economic impacts, impacts on 
national security, or any other relevant impacts. In considering 
whether to exclude a particular area from the designation, we identify 
the benefits of including the area in the designation, identify the 
benefits of excluding the area from the designation, and evaluate 
whether the benefits of exclusion outweigh the benefits of inclusion. 
If the analysis indicates that the benefits of exclusion outweigh the 
benefits of inclusion, the Secretary may exercise discretion to exclude 
the area only if such exclusion would not result in the extinction of 
the species. We describe below the process that we undertook for taking 
into consideration each category of impacts and our analyses of the 
relevant impacts.

Consideration of Economic Impacts

    Section 4(b)(2) of the Act and its implementing regulations require 
that we consider the economic impact that may result from a designation 
of critical habitat. To assess the probable economic impacts of a 
designation, we must first evaluate specific land uses or activities 
and projects that may occur in the area of the critical habitat. We 
then must evaluate the impacts that a specific critical habitat 
designation may have on restricting or modifying specific land uses or 
activities for the benefit of the species and its habitat within the 
areas proposed. We then identify which conservation efforts may be the 
result of the species being listed under the Act versus those 
attributed solely to the designation of critical habitat for this 
particular species. The probable economic impact of a proposed critical 
habitat designation is analyzed by comparing scenarios both ``with 
critical habitat'' and ``without critical habitat.''
    The ``without critical habitat'' scenario represents the baseline 
for the analysis, which includes the existing regulatory and socio-
economic burden imposed on landowners, managers, or other resource 
users potentially affected by the designation of critical habitat 
(e.g., under the Federal listing as well as other Federal, State, and 
local regulations). Therefore, the baseline represents the costs of all 
efforts attributable to the listing of the species under the Act (i.e., 
conservation of the species and its habitat incurred regardless of 
whether critical habitat is designated). The ``with critical habitat'' 
scenario describes the incremental impacts associated specifically with 
the designation of critical habitat for the species. The incremental 
conservation efforts and associated impacts would not be expected 
without the designation of critical habitat for the species. In other 
words, the incremental costs are those attributable solely to the 
designation of critical habitat, above and beyond the baseline costs. 
These are the costs we use when evaluating the benefits of inclusion 
and exclusion of particular areas from the final designation of 
critical habitat should we choose to conduct a discretionary 4(b)(2) 
exclusion analysis.
    For this particular designation, we developed an incremental 
effects memorandum (IEM) considering the probable incremental economic 
impacts that may result from this proposed designation of critical 
habitat. The information contained in our IEM was then used to develop 
a screening analysis of the probable effects of the designation of 
critical habitat for the prostrate milkweed (Industrial Economics, Inc. 
(IEc) 2021, entire). We began by conducting a screening analysis of the 
proposed designation of critical habitat in order to focus our analysis 
on the key factors that are likely to result in incremental economic 
impacts. The purpose of the screening analysis is to filter out 
particular geographic areas of critical habitat that are already 
subject to such protections and are, therefore, unlikely to incur 
incremental economic impacts. In particular, the screening analysis 
considers baseline costs (i.e., absent critical habitat designation) 
and includes any probable incremental economic impacts where land and 
water use may be subject to conservation plans, land management plans, 
best management practices, or regulations that protect the habitat area 
as a result of the Federal listing status of the species. Ultimately, 
the screening analysis allows us to focus our analysis on evaluating 
the specific areas or sectors that may incur probable incremental 
economic impacts as a result of the designation. If the proposed 
critical habitat designation contains any unoccupied units, the 
screening analysis assesses whether those units require additional 
management or conservation efforts that may incur incremental economic 
impacts. This screening analysis combined with the information 
contained in our IEM constitute what we consider to be our draft 
economic analysis (DEA) of the proposed critical habitat designation 
for the prostrate milkweed; our DEA is summarized in the narrative 
below.
    Executive Orders (E.O.s) 12866 and 13563 direct Federal agencies to 
assess the costs and benefits of available regulatory alternatives in 
quantitative (to the extent feasible) and qualitative terms. Consistent 
with the E.O. regulatory analysis requirements, our effects analysis 
under the Act may take into consideration impacts to both directly and 
indirectly affected entities, where practicable and reasonable. If 
sufficient data are available, we assess to the extent practicable the 
probable impacts to both directly and indirectly affected entities. As 
part of our screening analysis, we considered the types of economic 
activities that are likely to occur within the areas likely affected by 
the critical habitat designation. In our evaluation of the probable 
incremental economic impacts

[[Page 8527]]

that may result from the proposed designation of critical habitat for 
the prostrate milkweed, first we identified, in the IEM dated March 11, 
2021, probable incremental economic impacts associated with the 
following categories of activities: (1) Construction of a new highway; 
and (2) potential future border wall construction. We considered each 
industry or category individually. Additionally, we considered whether 
their activities have any Federal involvement. Critical habitat 
designation generally will not affect activities that do not have any 
Federal involvement; under the Act, designation of critical habitat 
only affects activities conducted, funded, permitted, or authorized by 
Federal agencies. If we list the species, in areas where the prostrate 
milkweed is present, Federal agencies would be required to consult with 
the Service under section 7 of the Act on activities they fund, permit, 
or implement that may affect the species. If, when we list the species, 
we also finalize this proposed critical habitat designation, our 
consultations would include an evaluation of measures to avoid the 
destruction or adverse modification of critical habitat.
    In our IEM, we attempted to clarify the distinction between the 
effects that would result from the species being listed and those 
attributable to the critical habitat designation (i.e., difference 
between the jeopardy and adverse modification standards) for the 
prostrate milkweed's critical habitat. Because the designation of 
critical habitat for prostrate milkweed was proposed concurrently with 
the listing, it has been our experience that it is more difficult to 
discern which conservation efforts are attributable to the species 
being listed and those which will result solely from the designation of 
critical habitat. However, the following specific circumstances in this 
case help to inform our evaluation: (1) The essential physical or 
biological features identified for critical habitat are the same 
features essential for the life requisites of the species, and (2) any 
actions that would result in sufficient harm or harassment to 
constitute jeopardy to the prostrate milkweed would also likely 
adversely affect the essential physical or biological features of 
critical habitat. The IEM outlines our rationale concerning this 
limited distinction between baseline conservation efforts and 
incremental impacts of the designation of critical habitat for this 
species. This evaluation of the incremental effects has been used as 
the basis to evaluate the probable incremental economic impacts of this 
proposed designation of critical habitat.
    The proposed critical habitat designation for the prostrate 
milkweed includes eight units totaling 691.3 ac (279.8 ha). All units 
are considered occupied by the prostrate milkweed and contain the 
physical and biological features essential to the conservation of the 
species. We are not proposing to designate any units of unoccupied 
habitat. Approximately 24 percent of the proposed designation is 
located on Federal land, 4 percent is on county-owned ROWs, and 71 
percent is on private land. In these areas, any actions that may affect 
the species or its habitat would also affect designated critical 
habitat, and it is unlikely that any additional conservation efforts 
would be recommended to address the adverse modification standard over 
and above those recommended as necessary to avoid jeopardizing the 
continued existence of prostrate milkweed. Therefore, the potential 
incremental economic effects of the critical habitat designation are 
expected to be limited to administrative costs.
    While this additional analysis will require time and resources by 
both the Federal action agency and the Service, it is believed that, in 
most circumstances, these costs would predominantly be administrative 
in nature and would not be significant. Nearly all (97 percent) of the 
proposed critical habitat overlaps designated critical habitat for the 
endangered Zapata bladderpod (Physaria thamnophila). Proposed critical 
habitat also overlaps with designated critical habitat for the 
endangered ashy dogweed (Thymophylla tephroleuca) and star cactus 
(Astrophytum asterias). Because of the overall small size of the 
proposed critical habitat, there would likely only be a few 
consultations, with minor conservation efforts that would likely result 
in relatively low probable economic impacts. It is likely that the 
majority of costs would occur on two of the eight proposed critical 
habitat units, which are on Federal land (both are owned by the 
Service). Any potential future border wall construction has been paused 
at this time.
    The probable incremental economic impacts of the prostrate milkweed 
critical habitat designation are expected to be limited to additional 
administrative effort as well as minor costs of conservation efforts 
resulting from a small number of future section 7 consultations. This 
is due to the fact that all of the proposed critical habitat areas are 
considered to be occupied by the species, and incremental economic 
impacts of critical habitat designation, other than administrative 
costs, are unlikely. The entities most likely to incur incremental 
costs are parties to section 7 consultations, including Federal action 
agencies and, in some cases, third parties, most frequently State 
agencies or municipalities. Activities we expect would be subject to 
consultations that may involve private entities as third parties are 
residential and commercial development that may occur on private lands. 
However, based on coordination efforts with State and local agencies, 
the cost to private entities within these sectors is expected to be 
relatively minor. We would expect no more than 1 formal consultation, 
10 information consultations, and 17 technical assistance efforts to 
occur annually over the next year in proposed critical habitat areas 
for the prostrate milkweed, with annual costs to the Service and action 
agencies of less than $37,800. Thus, the annual administrative burden 
is unlikely to reach $100 million, which is the threshold for a 
significant regulatory action under E.O. 12866.
    We are soliciting data and comments from the public on the DEA 
discussed above, as well as on all aspects of this proposed rule and 
our required determinations. During the development of a final 
designation, we will consider the information presented in the DEA and 
any additional information on economic impacts we receive during the 
public comment period to determine whether any specific areas should be 
excluded from the final critical habitat designation under authority of 
section 4(b)(2) and our implementing regulations at 50 CFR 17.90. If we 
receive credible information regarding the existence of a meaningful 
economic or other relevant impact supporting a benefit of exclusion, we 
will conduct an exclusion analysis for the relevant area or areas. We 
may also exercise the discretion to evaluate any other particular areas 
for possible exclusion. Furthermore, when we conduct an exclusion 
analysis based on impacts identified by experts in, or sources with 
firsthand knowledge about, impacts that are outside the scope of the 
Service's expertise, we will give weight to those impacts consistent 
with the expert or firsthand information unless we have rebutting 
information. We may exclude an area from critical habitat if we 
determine that the benefits of excluding the area outweigh the benefits 
of including the area, provided the exclusion will not result in the 
extinction of this species.

[[Page 8528]]

Consideration of National Security Impacts

    Section 4(a)(3)(B)(i) of the Act may not cover all DoD lands or 
areas that pose potential national-security concerns (e.g., a DoD 
installation that is in the process of revising its INRMP for a newly 
listed species or a species previously not covered). If a particular 
area is not covered under section 4(a)(3)(B)(i), then national-security 
or homeland-security concerns are not a factor in the process of 
determining what areas meet the definition of ``critical habitat.'' 
However, the Service must still consider impacts on national security, 
including homeland security, on those lands or areas not covered by 
section 4(a)(3)(B)(i), because section 4(b)(2) requires the Service to 
consider those impacts whenever it designates critical habitat. 
Accordingly, if DoD, Department of Homeland Security (DHS), or another 
Federal agency has requested exclusion based on an assertion of 
national-security or homeland-security concerns, or we have otherwise 
identified national-security or homeland-security impacts from 
designating particular areas as critical habitat, we generally have 
reason to consider excluding those areas.
    However, we cannot automatically exclude requested areas. When DoD, 
DHS, or another Federal agency requests exclusion from critical habitat 
on the basis of national-security or homeland-security impacts, we must 
conduct an exclusion analysis if the Federal requester provides 
credible information, including a reasonably specific justification of 
an incremental impact on national security that would result from the 
designation of that specific area as critical habitat. That 
justification could include demonstration of probable impacts, such as 
impacts to ongoing border-security patrols and surveillance activities, 
or a delay in training or facility construction, as a result of 
compliance with section 7(a)(2) of the Act. If the agency requesting 
the exclusion does not provide us with a reasonably specific 
justification, we will contact the agency to recommend that it provide 
a specific justification or clarification of its concerns relative to 
the probable incremental impact that could result from the designation. 
If we conduct an exclusion analysis because the agency provides a 
reasonably specific justification or because we decide to exercise the 
discretion to conduct an exclusion analysis, we will defer to the 
expert judgment of DoD, DHS, or another Federal agency as to: (1) 
Whether activities on its lands or waters, or its activities on other 
lands or waters, have national-security or homeland-security 
implications; (2) the importance of those implications; and (3) the 
degree to which the cited implications would be adversely affected in 
the absence of an exclusion. In that circumstance, in conducting a 
discretionary section 4(b)(2) exclusion analysis, we will give great 
weight to national-security and homeland-security concerns in analyzing 
the benefits of exclusion.
    Under section 4(b)(2) of the Act, we also consider whether a 
national-security or homeland-security impact might exist on lands 
owned or managed by DoD or DHS, or on any other lands. In preparing 
this proposal, we have determined that the lands within the proposed 
designation of critical habitat for prostrate milkweed are not owned or 
managed by DoD or DHS. Although two proposed units of critical habitat 
are located along the border, we do not anticipate that there will be 
an impact on national security or homeland security. We will work with 
CBP to ensure appropriate collaboration in our national security and 
conservation efforts. However, if through the public comment period we 
receive credible information regarding impacts on national security or 
homeland security from designating particular areas as critical 
habitat, then as part of developing the final designation of critical 
habitat, we will conduct a discretionary exclusion analysis to 
determine whether to exclude those areas under authority of section 
4(b)(2) and our implementing regulations at 50 CFR 17.90.

Consideration of Other Relevant Impacts

    Under section 4(b)(2) of the Act, we consider any other relevant 
impacts, in addition to economic impacts and impacts on national 
security discussed above. Other relevant impacts may include, but are 
not limited to, impacts to Tribes, States, local governments, public 
health and safety, community interests, the environment (such as 
increased risk of wildfire or pest and invasive species management), 
Federal lands, and conservation plans, agreements, or partnerships. To 
identify other relevant impacts that may affect the exclusion analysis, 
we consider a number of factors, including whether there are permitted 
conservation plans covering the species in the area--such as HCPs, safe 
harbor agreements (SHAs), or candidate conservation agreements with 
assurances (CCAAs)--or whether there are non-permitted conservation 
agreements and partnerships that may be impaired by designation of, or 
exclusion from, critical habitat. In addition, we look at whether 
Tribal conservation plans or partnerships, Tribal resources, or 
government-to-government relationships of the United States with Tribal 
entities may be affected by the designation. We also consider any 
State, local, public-health, community-interest, environmental, or 
social impacts that might occur because of the designation.
    We have not identified any areas to consider for exclusion from 
critical habitat based on other relevant impacts because areas included 
in the proposed critical habitat are not covered under any permitted 
conservation plans (i.e., SHAs), CCAAs, non-permitted conservation 
agreements and partnerships, Tribal conservation plans or partnerships, 
or have any State, local, public-health, community-interest, 
environmental, or social impacts.
    However, during the development of a final designation, we will 
consider all information currently available or received during the 
public comment period. If we receive credible information regarding the 
existence of a meaningful impact supporting a benefit of excluding any 
areas, we will undertake an exclusion analysis and determine whether 
those areas should be excluded from the final critical habitat 
designation under the authority of section 4(b)(2) and our implementing 
regulations at 50 CFR 17.90. We may also exercise the discretion to 
undertake exclusion analyses for other areas as well, and we will 
describe all of our exclusion analyses as part of a final critical 
habitat determination.

Summary of Exclusions Considered Under 4(b)(2) of the Act

    At this time, we are not considering any exclusions from the 
proposed designation based on economic impacts, national security 
impacts, or other relevant impacts--such as partnerships, management, 
or protection afforded by cooperative management efforts--under section 
4(b)(2) of the Act. In this proposed rule, we are seeking credible 
information from the public regarding the existence of a meaningful 
impact supporting a benefit of excluding any areas that would be used 
in an exclusion analysis that may result in the exclusion of areas from 
the final critical habitat designation. (Please see FOR FURTHER 
INFORMATION CONTACT for instructions on how to submit comments).

[[Page 8529]]

Required Determinations

Clarity of the Rule

    We are required by Executive Orders 12866 and 12988 and by the 
Presidential Memorandum of June 1, 1998, to write all rules in plain 
language. This means that each rule we publish must:
    (1) Be logically organized;
    (2) Use the active voice to address readers directly;
    (3) Use clear language rather than jargon;
    (4) Be divided into short sections and sentences; and
    (5) Use lists and tables wherever possible.
    If you feel that we have not met these requirements, send us 
comments by one of the methods listed in ADDRESSES. To better help us 
revise the rule, your comments should be as specific as possible. For 
example, you should tell us the numbers of the sections or paragraphs 
that are unclearly written, which sections or sentences are too long, 
the sections where you feel lists or tables would be useful, etc.

Regulatory Planning and Review (Executive Orders 12866 and 13563)

    Executive Order 12866 provides that the Office of Information and 
Regulatory Affairs (OIRA) in the Office of Management and Budget will 
review all significant rules. OIRA has determined that this rule is not 
significant.
    Executive Order 13563 reaffirms the principles of E.O. 12866 while 
calling for improvements in the Nation's regulatory system to promote 
predictability, to reduce uncertainty, and to use the best, most 
innovative, and least burdensome tools for achieving regulatory ends. 
The Executive order directs agencies to consider regulatory approaches 
that reduce burdens and maintain flexibility and freedom of choice for 
the public where these approaches are relevant, feasible, and 
consistent with regulatory objectives. E.O. 13563 emphasizes further 
that regulations must be based on the best available science and that 
the rulemaking process must allow for public participation and an open 
exchange of ideas. We have developed this proposed rule in a manner 
consistent with these requirements.

Regulatory Flexibility Act (5 U.S.C. 601 et seq.)

    Under the Regulatory Flexibility Act (RFA; 5 U.S.C. 601 et seq.), 
as amended by the Small Business Regulatory Enforcement Fairness Act of 
1996 (SBREFA; 5 U.S.C. 801 et seq.), whenever an agency is required to 
publish a notice of rulemaking for any proposed or final rule, it must 
prepare and make available for public comment a regulatory flexibility 
analysis that describes the effects of the rule on small entities 
(i.e., small businesses, small organizations, and small government 
jurisdictions). However, no regulatory flexibility analysis is required 
if the head of the agency certifies the rule will not have a 
significant economic impact on a substantial number of small entities. 
The SBREFA amended the RFA to require Federal agencies to provide a 
certification statement of the factual basis for certifying that the 
rule will not have a significant economic impact on a substantial 
number of small entities.
    According to the Small Business Administration, small entities 
include small organizations such as independent nonprofit 
organizations; small governmental jurisdictions, including school 
boards and city and town governments that serve fewer than 50,000 
residents; and small businesses (13 CFR 121.201). Small businesses 
include manufacturing and mining concerns with fewer than 500 
employees, wholesale trade entities with fewer than 100 employees, 
retail and service businesses with less than $5 million in annual 
sales, general and heavy construction businesses with less than $27.5 
million in annual business, special trade contractors doing less than 
$11.5 million in annual business, and agricultural businesses with 
annual sales less than $750,000. To determine whether potential 
economic impacts to these small entities are significant, we considered 
the types of activities that might trigger regulatory impacts under 
this designation as well as types of project modifications that may 
result. In general, the term ``significant economic impact'' is meant 
to apply to a typical small business firm's business operations.
    Under the RFA, as amended, and as understood in light of recent 
court decisions, Federal agencies are required to evaluate the 
potential incremental impacts of rulemaking on those entities directly 
regulated by the rulemaking itself; in other words, the RFA does not 
require agencies to evaluate the potential impacts to indirectly 
regulated entities. The regulatory mechanism through which critical 
habitat protections are realized is section 7 of the Act, which 
requires Federal agencies, in consultation with the Service, to ensure 
that any action authorized, funded, or carried out by the agency is not 
likely to destroy or adversely modify critical habitat. Therefore, 
under section 7, only Federal action agencies are directly subject to 
the specific regulatory requirement (avoiding destruction and adverse 
modification) imposed by critical habitat designation. Consequently, it 
is our position that only Federal action agencies would be directly 
regulated if we adopt the proposed critical habitat designation. The 
RFA does not require evaluation of the potential impacts to entities 
not directly regulated. Moreover, Federal agencies are not small 
entities. Therefore, because no small entities would be directly 
regulated by this rulemaking, the Service certifies that, if made final 
as proposed, the proposed critical habitat designation will not have a 
significant economic impact on a substantial number of small entities.
    In summary, we have considered whether the proposed designation 
would result in a significant economic impact on a substantial number 
of small entities. For the above reasons and based on currently 
available information, we certify that, if made final, the proposed 
critical habitat designation would not have a significant economic 
impact on a substantial number of small business entities. Therefore, 
an initial regulatory flexibility analysis is not required.

Energy Supply, Distribution, or Use--Executive Order 13211

    Executive Order 13211 (Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use) requires 
agencies to prepare Statements of Energy Effects when undertaking 
certain actions. In our economic analysis, we did not find that this 
proposed critical habitat designation would significantly affect energy 
supplies, distribution, or use. Therefore, this action is not a 
significant energy action, and no Statement of Energy Effects is 
required.

Unfunded Mandates Reform Act (2 U.S.C. 1501 et seq.)

    In accordance with the Unfunded Mandates Reform Act (2 U.S.C. 1501 
et seq.), we make the following finding:
    (1) This proposed rule would not produce a Federal mandate. In 
general, a Federal mandate is a provision in legislation, statute, or 
regulation that would impose an enforceable duty upon State, local, or 
Tribal governments, or the private sector, and includes both ``Federal 
intergovernmental mandates'' and ``Federal private sector mandates.'' 
These terms are defined in 2 U.S.C. 658(5)-(7). ``Federal 
intergovernmental mandate'' includes a regulation that ``would impose 
an enforceable duty upon State, local, or Tribal governments'' with two 
exceptions. It

[[Page 8530]]

excludes ``a condition of Federal assistance.'' It also excludes ``a 
duty arising from participation in a voluntary Federal program,'' 
unless the regulation ``relates to a then-existing Federal program 
under which $500,000,000 or more is provided annually to State, local, 
and Tribal governments under entitlement authority,'' if the provision 
would ``increase the stringency of conditions of assistance'' or 
``place caps upon, or otherwise decrease, the Federal Government's 
responsibility to provide funding,'' and the State, local, or Tribal 
governments ``lack authority'' to adjust accordingly. At the time of 
enactment, these entitlement programs were: Medicaid; Aid to Families 
with Dependent Children work programs; Child Nutrition; Food Stamps; 
Social Services Block Grants; Vocational Rehabilitation State Grants; 
Foster Care, Adoption Assistance, and Independent Living; Family 
Support Welfare Services; and Child Support Enforcement. ``Federal 
private sector mandate'' includes a regulation that ``would impose an 
enforceable duty upon the private sector, except (i) a condition of 
Federal assistance or (ii) a duty arising from participation in a 
voluntary Federal program.''
    The designation of critical habitat does not impose a legally 
binding duty on non-Federal Government entities or private parties. 
Under the Act, the only regulatory effect is that Federal agencies must 
ensure that their actions do not destroy or adversely modify critical 
habitat under section 7. While non-Federal entities that receive 
Federal funding, assistance, or permits, or that otherwise require 
approval or authorization from a Federal agency for an action, may be 
indirectly impacted by the designation of critical habitat, the legally 
binding duty to avoid destruction or adverse modification of critical 
habitat rests squarely on the Federal agency. Furthermore, to the 
extent that non-Federal entities are indirectly impacted because they 
receive Federal assistance or participate in a voluntary Federal aid 
program, the Unfunded Mandates Reform Act would not apply, nor would 
critical habitat shift the costs of the large entitlement programs 
listed above onto State governments.
    (2) We do not believe that this rule would significantly or 
uniquely affect small governments because it will not produce a Federal 
mandate of $100 million or greater in any year, that is, it is not a 
``significant regulatory action'' under the Unfunded Mandates Reform 
Act. The designation of critical habitat imposes no obligations on 
State or local governments. Therefore, a Small Government Agency Plan 
is not required.

Takings--Executive Order 12630

    In accordance with E.O. 12630 (Government Actions and Interference 
with Constitutionally Protected Private Property Rights), we have 
analyzed the potential takings implications of designating critical 
habitat for prostrate milkweed in a takings implications assessment. 
The Act does not authorize the Service to regulate private actions on 
private lands or confiscate private property as a result of critical 
habitat designation. Designation of critical habitat does not affect 
land ownership, or establish any closures, or restrictions on use of or 
access to the designated areas. Furthermore, the designation of 
critical habitat does not affect landowner actions that do not require 
Federal funding or permits, nor does it preclude development of habitat 
conservation programs or issuance of incidental take permits to permit 
actions that do require Federal funding or permits to go forward. 
However, Federal agencies are prohibited from carrying out, funding, or 
authorizing actions that would destroy or adversely modify critical 
habitat. A takings implications assessment has been completed for the 
proposed designation of critical habitat for prostrate milkweed, and it 
concludes that, if adopted, this designation of critical habitat does 
not pose significant takings implications for lands within or affected 
by the designation.

Federalism--Executive Order 13132

    In accordance with E.O. 13132 (Federalism), this proposed rule does 
not have significant federalism effects. A federalism summary impact 
statement is not required. In keeping with Department of the Interior 
and Department of Commerce policy, we requested information from, and 
coordinated development of this proposed critical habitat designation 
with, appropriate State resource agencies. From a federalism 
perspective, the designation of critical habitat directly affects only 
the responsibilities of Federal agencies. The Act imposes no other 
duties with respect to critical habitat, either for States and local 
governments, or for anyone else. As a result, the proposed rule does 
not have substantial direct effects either on the States, or on the 
relationship between the national government and the States, or on the 
distribution of powers and responsibilities among the various levels of 
government. The proposed designation may have some benefit to these 
governments because the areas that contain the features essential to 
the conservation of the species are more clearly defined, and the 
physical or biological features of the habitat necessary for the 
conservation of the species are specifically identified. This 
information does not alter where and what federally sponsored 
activities may occur. However, it may assist State and local 
governments in long-range planning because they no longer have to wait 
for case-by-case section 7 consultations to occur.
    Where State and local governments require approval or authorization 
from a Federal agency for actions that may affect critical habitat, 
consultation under section 7(a)(2) of the Act would be required. While 
non-Federal entities that receive Federal funding, assistance, or 
permits, or that otherwise require approval or authorization from a 
Federal agency for an action, may be indirectly impacted by the 
designation of critical habitat, the legally binding duty to avoid 
destruction or adverse modification of critical habitat rests squarely 
on the Federal agency.

Civil Justice Reform--Executive Order 12988

    In accordance with Executive Order 12988 (Civil Justice Reform), 
the Office of the Solicitor has determined that the rule would not 
unduly burden the judicial system and that it meets the requirements of 
sections 3(a) and 3(b)(2) of the order. We have proposed designating 
critical habitat in accordance with the provisions of the Act. To 
assist the public in understanding the habitat needs of the species, 
this proposed rule identifies the physical or biological features 
essential to the conservation of the species. The proposed areas of 
designated critical habitat are presented on maps, and the proposed 
rule provides several options for the interested public to obtain more 
detailed location information, if desired.

Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.)

    This rule does not contain information collection requirements, and 
a submission to the Office of Management and Budget (OMB) under the 
Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.) is not 
required. We may not conduct or sponsor and you are not required to 
respond to a collection of information unless it displays a currently 
valid OMB control number.

National Environmental Policy Act (42 U.S.C. 4321 et seq.)

    It is our position that, outside the jurisdiction of the U.S. Court 
of Appeals for the Tenth Circuit, we do not need to

[[Page 8531]]

prepare environmental analyses pursuant to the National Environmental 
Policy Act (NEPA; 42 U.S.C. 4321 et seq.) in connection with 
regulations adopted pursuant to section 4(a) of the Act. We published a 
notice outlining our reasons for this determination in the Federal 
Register on October 25, 1983 (48 FR 49244). This position was upheld by 
the U.S. Court of Appeals for the Ninth Circuit (Douglas County v. 
Babbitt, 48 F.3d 1495 (9th Cir. 1995), cert. denied 516 U.S. 1042 
(1996)).

Government-to-Government Relationship With Tribes

    In accordance with the President's memorandum of April 29, 1994 
(Government-to-Government Relations with Native American Tribal 
Governments; 59 FR 22951), Executive Order 13175 (Consultation and 
Coordination with Indian Tribal Governments), and the Department of the 
Interior's manual at 512 DM 2, we readily acknowledge our 
responsibility to communicate meaningfully with recognized Federal 
Tribes on a government-to-government basis. In accordance with 
Secretarial Order 3206 of June 5, 1997 (American Indian Tribal Rights, 
Federal-Tribal Trust Responsibilities, and the Endangered Species Act), 
we readily acknowledge our responsibilities to work directly with 
Tribes in developing programs for healthy ecosystems, to acknowledge 
that Tribal lands are not subject to the same controls as Federal 
public lands, to remain sensitive to Indian culture, and to make 
information available to Tribes. We have determined that no Tribal 
lands fall within the boundaries of the proposed critical habitat for 
the prostrate milkweed, so no Tribal lands would be affected by the 
proposed designation.

References Cited

    A complete list of references cited in this rulemaking is available 
on the internet at https://www.regulations.gov and upon request from 
the Texas Coastal Ecological Services Field Office (see FOR FURTHER 
INFORMATION CONTACT).

Authors

    The primary authors of this proposed rule are the staff members of 
the U.S. Fish and Wildlife Service's Species Assessment Team and the 
Texas Coastal Ecological Services Field Office.

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Reporting and 
recordkeeping requirements, Transportation.

Proposed Regulation Promulgation

    Accordingly, we propose to amend part 17, subchapter B of chapter 
I, title 50 of the Code of Federal Regulations, as set forth below:

PART 17--ENDANGERED AND THREATENED WILDLIFE AND PLANTS

0
1. The authority citation for part 17 continues to read as follows:

    Authority:  16 U.S.C. 1361-1407; 1531-1544; and 4201-4245, 
unless otherwise noted.

0
2. Amend Sec.  17.12(h) by adding an entry for ``Asclepias prostrata'' 
to the List of Endangered and Threatened Plants in alphabetical order 
under FLOWERING PLANTS to read as follows:


Sec.  17.12   Endangered and threatened plants.

* * * * *
    (h) * * *

----------------------------------------------------------------------------------------------------------------
                                                                                          Listing citations and
         Scientific name              Common name         Where listed        Status         applicable rules
----------------------------------------------------------------------------------------------------------------
Flowering Plants
 
                                                  * * * * * * *
Asclepias prostrata.............  Prostrate milkweed.  Wherever found....            E   [Federal Register
                                                                                          citation when
                                                                                          published as a final
                                                                                          rule]; 50 CFR
                                                                                          17.96(a).\CH\
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------

0
3. Amend Sec.  17.96(a) by adding an entry for ``Family Apocynaceae: 
Asclepias prostrata (Prostrate Milkweed)'' after the entry for ``Family 
Apiaceae: Lomatium cookii (Cook's lomatium, Cook's desert parsley)'' to 
read as follows:


Sec.  17.96   Critical habitat--plants.

    (a) * * *
    Family Apocynaceae: Asclepias prostrata (Prostrate Milkweed)
    (1) Critical habitat units are depicted for Starr and Zapata 
Counties, Texas, on the maps in this entry.
    (2) Within these areas, the physical or biological features 
essential to the conservation of Asclepias prostrata consist of the 
following components:
    (i) Well-drained sandy soil overlying strata of sandstone or 
indurated caliche;
    (ii) High soil gypsum concentration;
    (iii) Open savannas and grasslands of the Tamaulipan shrubland 
ecological region;
    (iv) Vegetation composition that includes abundant, diverse pollen 
and nectar plants and healthy populations of native bee and wasp 
species; and
    (v) Less than 20 percent cover of Pennisetum ciliare (buffelgrass).
    (3) Critical habitat does not include manmade structures (such as 
buildings, aqueducts, runways, roads, and other paved areas) and the 
land on which they are located existing within the legal boundaries on 
[EFFECTIVE DATE OF RULE].
    (4) Data layers defining map units were created using Texas Natural 
Diversity Database (2019-2020) survey data of the documented Asclepias 
prostrata locations in the United States to determine the geological 
formations and soil types they occupy.
    (i) We used the Esri ArcMap software to overlay the geographic 
coordinates of populations on a digitized map of Texas surface geology 
and a digitized soil survey map. We then clipped those areas of 
potential to lands that have documented populations of Asclepias 
prostrata.
    (ii) The maps in this entry, as modified by any accompanying 
regulatory text, establish the boundaries of the critical habitat 
designation. The coordinates or plot points or both on which each map 
is based are available to the public at the Service's internet site at 
https://www.fws.gov/southwest/es/TexasCoastal/, at https://www.regulations.gov at Docket No. FWS-R2-ES-2021-0041, and at the field 
office responsible for this designation. You may obtain field office 
location information by contacting one of the Service regional offices, 
the addresses of which are listed at 50 CFR 2.2.
    (5) Note: Index map follows:
BILLING CODE 4333-15-P

[[Page 8532]]

[GRAPHIC] [TIFF OMITTED] TP15FE22.016

    (6) Unit 1: Zapata County, Texas.
    (i) Unit 1 consists of 6 areas totaling 10.51 ac (4.25 ha) east of 
highway 83 in northwest Zapata County. This unit is on private land and 
a county road right of way.

[[Page 8533]]

    (ii) Map of Unit 1 follows:
    [GRAPHIC] [TIFF OMITTED] TP15FE22.017
    

[[Page 8534]]


    (7) Unit 2: Starr County, Texas.
    (i) Unit 2 consists of 105.43 ac (42.67 ha) in the Arroyo Ramirez 
tract of Lower Rio Grande Valley National Wildlife Refuge. This unit is 
in southwestern Starr County adjacent to the Rio Grande on the U.S.-
Mexico border. The entire unit is on land owned and managed by the 
Service.

[[Page 8535]]

    (ii) Map of Unit 2 follows:
    [GRAPHIC] [TIFF OMITTED] TP15FE22.018
    

[[Page 8536]]


    (8) Unit 3: Starr County, Texas.
    (i) Unit 3 consists of 4.0 ac (1.62 ha) along both sides of a road 
right of way on private land in southern Starr County.
    (ii) Map of Unit 3 follows:

[[Page 8537]]

[GRAPHIC] [TIFF OMITTED] TP15FE22.019

    (9) Unit 4: Starr County, Texas.
    (i) Unit 4 consists of 4.2 ac (1.7 ha) along the unpaved right of 
way of Los Arrieros Loop, a county road in southwestern Starr County.

[[Page 8538]]

    (ii) Map of Unit 4 follows:
    [GRAPHIC] [TIFF OMITTED] TP15FE22.020
    
    (10) Unit 5: Starr County, Texas.
    (i) Unit 5 consists of 62.49 ac (25.29 ha) in the Arroyo Morteros 
tract of the Lower Rio Grande Valley National Wildlife Refuge. This 
unit is in western Starr County adjacent to the Rio Grande on the U.S.-
Mexico border. The entire unit is on land owned and managed by the 
Service.
    (ii) Map of Unit 5 follows:

[[Page 8539]]

[GRAPHIC] [TIFF OMITTED] TP15FE22.021

    (11) Unit 6: Starr County, Texas.
    (i) Unit 6 consists of 484.32 ac (196.0 ha) entirely on privately 
owned land and the adjacent right of way of San

[[Page 8540]]

Julian Road. This unit is in western Starr County.
    (ii) Map of Unit 6 follows:
    [GRAPHIC] [TIFF OMITTED] TP15FE22.022
    

[[Page 8541]]


    (12) Unit 7: Starr County, Texas.
    (i) Unit 7 consists of 19.35 ac (7.83 ha) along both sides of a 
right of way and adjacent private land in western Starr County.
    (ii) Map of Unit 7 follows:
    [GRAPHIC] [TIFF OMITTED] TP15FE22.023
    
    (13) Unit 8: Zapata County, Texas.
    (i) Unit 8 consists of 1.04 ac (0.42 ha) on private land in central 
Zapata County.

[[Page 8542]]

    (ii) Map of Unit 8 follows:
    [GRAPHIC] [TIFF OMITTED] TP15FE22.024
    

[[Page 8543]]


* * * * *

Martha Williams,
Principal Deputy Director, Exercising the Delegated Authority of the 
Director, U.S. Fish and Wildlife Service.
[FR Doc. 2022-02544 Filed 2-14-22; 8:45 am]
BILLING CODE 4333-15-C