Endangered and Threatened Wildlife and Plants; Removing Oenothera coloradensis (Colorado Butterfly Plant) From the Federal List of Endangered and Threatened Plants, 59570-59588 [2019-24124]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 84, Number 214 (Tuesday, November 5, 2019)]
[Rules and Regulations]
[Pages 59570-59588]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-24124]


=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R6-ES-2018-0008; FXES11130900000C6-189-FF09E30000]
RIN 1018-BC02


Endangered and Threatened Wildlife and Plants; Removing Oenothera 
coloradensis (Colorado Butterfly Plant) From the Federal List of 
Endangered and Threatened Plants

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: We, the U.S. Fish and Wildlife Service (Service), remove the 
Colorado butterfly plant (Oenothera coloradensis, currently listed as 
Gaura neomexicana ssp. coloradensis) from the Federal List of 
Endangered and Threatened Plants (List) due to recovery. This 
determination is based on a thorough review of the best available 
scientific and commercial data, which indicate that the threats to the 
Colorado butterfly plant have been eliminated or reduced to the point 
that it has recovered, and that this plant is no longer likely to 
become endangered in the foreseeable future and, therefore, no longer 
meets the definition of a threatened species under the Endangered 
Species Act of 1973, as amended (Act). This final rule also removes the 
currently designated critical habitat for the Colorado butterfly plant.

DATES: This rule is effective December 5, 2019.

ADDRESSES: This final rule is available on the internet at https://www.regulations.gov under Docket No. FWS-R6-ES-2018-0008. Comments and 
materials we received, as well as supporting documentation we used in 
preparing this rule, are available for public inspection at https://www.regulations.gov under Docket No. FWS-R6-ES-2018-0008. All of the 
comments, materials, and documentation that we considered in this 
rulemaking are available by appointment, during normal business hours, 
at our Wyoming Ecological Services Field Office (see FOR FURTHER 
INFORMATION CONTACT, below).

FOR FURTHER INFORMATION CONTACT: Tyler A. Abbott, Field Supervisor, 
telephone: 307-772-2374. Direct all questions or requests for 
additional information to: COLORADO BUTTERFLY PLANT QUESTIONS, U.S. 
Fish and Wildlife Service, Wyoming Ecological Services Field Office, 
5353 Yellowstone Road, Suite 308A, Cheyenne, WY 82009. Individuals who 
are hearing-impaired or speech-impaired may call the Federal Relay 
Service at 800-877-8339.

SUPPLEMENTARY INFORMATION: 

Previous Federal Actions

    On June 8, 2018, we published a proposed rule to remove Colorado 
butterfly plant from the List of Endangered and Threatened Plants 
(i.e., to ``delist'' the species) (83 FR 26623). Please refer to that 
proposed rule for a detailed description of the Federal actions 
concerning this species that occurred prior to June 8, 2018.

Species Description and Life History

    Detailed information regarding the Colorado butterfly plant's 
biology and life history can be found in the biological report for 
Colorado butterfly plant (USFWS 2017a, pp. 6-7). The biological report 
is an in-depth but not exhaustive review of the species' biology and 
threats, an evaluation of its biological status, and an assessment of 
the resources and conditions needed to maintain long-term viability. 
The report includes analyses of the species' viability in terms of its 
resiliency, redundancy, and representation (USFWS 2017a, entire). 
Resiliency is the ability of the species to maintain healthy 
populations that can withstand annual environmental variation and 
stochastic events. Redundancy is the ability of the species to maintain 
an adequate number and distribution of populations that can withstand 
catastrophic events. Representation is the ability of the species to 
adapt to changing environmental conditions through genetic, ecological, 
demographic, and behavioral diversity across its range. We summarize 
relevant information from the biological report below.
    The Colorado butterfly plant is a short-lived perennial herb that 
is monocarpic or semelparous, meaning that it flowers once, sets seed, 
and then dies. Flowering plants may, on rare occasions, flower a second 
year or become vegetative the year after flowering (Floyd 1995, pp. 10-
15, 32). Pollinators for related species of Gaura and Colylophus 
(Onagraceae, tribe Onagreae) consist of noctuid moths (Noctuidae) and 
halictid bees (Lasioglossum; Clinebell et al. 2004, p. 378); both moths 
and bees have been identified visiting Colorado butterfly plant flowers 
during annual censusing (USFWS 2016b, entire). Additionally, one study 
found that the Colorado butterfly plant does not exhibit a bimodal (day 
and night) pollination system that is seen in other Gaura species, 
since the majority of pollination occurs at night by noctuid moths 
(Krakos et al. 2013, entire).
    The Colorado butterfly plant is self-compatible (Floyd 1995, p. 4), 
meaning that plants produce flowers that are capable of forming viable 
seed from pollen from the same plant. There are no apparent adaptations 
for dispersal; many seeds fall to the ground around parent plants 
(Floyd and Ranker 1998, p. 854), and, because the seed floats, others 
may be dispersed downstream. Livestock and native ungulates could 
provide an important dispersal mechanism as well, through ingestion of 
the seeds (USFWS 2012, p. 27). Populations of this species show 
evidence of a seedbank, an adaptation that enables the species to take 
advantage of favorable growing seasons, particularly in flood-prone 
areas (Holzel and Otte 2004, p. 279).
    The number of individuals in a population of Colorado butterfly 
plants appears to be influenced by rates of seedling establishment and 
survival of vegetative rosettes to reproductive maturity. These factors 
may be influenced by summer precipitation (Floyd and Ranker 1998, p. 
858; Fertig

[[Page 59571]]

2000, p. 13). More recent evaluation suggests that the combination of 
cool and moist spring months is important in germination, and that 
germination levels influence the outcome of flowering plant population 
census in subsequent years. Additionally, summer conditions, and 
temperature in particular, appear to be an important mortality factor 
rather than influencing germination (Laursen and Heidel 2003, p. 6). 
Differences in soil moisture and vegetation cover may also influence 
recruitment success (Munk et al. 2002, p. 123).
    The vegetative rosettes within a population may provide an 
important and particularly resilient stage of the life history of this 
species. Individual vegetative rosettes appear to be capable of 
surviving adverse stochastic events such as flooding (Mountain West 
Environmental Services 1985, pp. 2-3) and adverse climatic years when 
new seedling establishment is low. Therefore, episodic establishment of 
large seedling recruitment classes may be important for the long-term 
growth, replenishment, and survival of populations (Floyd and Ranker 
1998, entire).

Taxonomy

    The Colorado butterfly plant, a member of the evening primrose 
family (Onagraceae), was listed as Gaura neomexicana ssp. coloradensis 
in 2000 (65 FR 62302; October 18, 2000). Molecular studies by Hoggard 
et al. (2004, p. 143) and Levin et al. (2004, pp. 151-152) and 
subsequent revisions of the classification of the family Onagraceae 
transferred the taxon previously known as Gaura neomexicana Wooton to 
Oenothera as Oenothera coloradensis ssp. neomexicana (Wooton) W.L. 
Wagner & Hoch (Wagner et al. 2007, p. 211). More recent analyses showed 
that there are no infraspecific entities (any taxa below the rank of 
species) within the taxon; the listed entity is now recognized as 
Oenothera coloradensis (Wagner et al. 2013, p. 67). A more detailed 
assessment of the taxonomy of the Colorado butterfly plant is available 
in the species biological report (USFWS 2017a, pp. 4--6). The taxonomic 
and nomenclatural changes do not alter the description, range, or 
threat status of the listed entity. Throughout this final rule, we will 
use the current scientific name and rank, Oenothera coloradensis, for 
the Colorado butterfly plant.

Species Abundance, Habitat, and Distribution

    The Colorado butterfly plant is a regional endemic riparian species 
known from 34 12-digit hydrologic unit code (HUC) watersheds (28 extant 
and 6 extirpated), found from Boulder, Douglas, Larimer, and Weld 
Counties in Colorado; Laramie and Platte Counties in Wyoming; and 
western Kimball County in Nebraska (see the figure, below). Prior to 
1984, few extensive searches for the plant had been conducted, and data 
taken from herbarium specimens were the primary basis of understanding 
the extent of the species' historical distribution. At that time, the 
plant was known from a few historical and presumably extirpated 
locations in southeastern Wyoming and several locations in northern 
Colorado, as well as from three extant occurrences in Laramie County in 
Wyoming and Weld County in Colorado. Prior to listing, extensive 
surveys were conducted in 1998, to document the status of the known 
occurrences, and all still contained Colorado butterfly plants (Fertig 
1998a, entire).
BILLING CODE 4333-15-P

[[Page 59572]]

[GRAPHIC] [TIFF OMITTED] TR05NO19.005

BILLING CODE 4333-15-C

Habitat Description

    The Colorado butterfly plant occurs on subirrigated (water reaches 
plant root zone from below the soil surface), alluvial soils derived 
from conglomerates, sandstones, and tuffaceous (light, porous rock 
formed by consolidation of volcanic ash) mudstones and siltstones of 
the Tertiary White River, Arikaree, and Oglalla Formations (Love and 
Christiansen 1985 in Fertig 2000, p. 6) on level or slightly sloping 
floodplains and drainage bottoms at elevations of 1,524-1,951

[[Page 59573]]

meters (m) (5,000-6,400 feet (ft)). Populations are typically found in 
habitats created and maintained by streams active within their 
floodplains, with vegetation that is relatively open and not overly 
dense or overgrown (65 FR 62302; October 18, 2000). Populations occur 
in a range of ecological settings, including streamside, outside of the 
stream channel but within the floodplain, and spring-fed wet meadows. 
The plant is often found in, but not restricted to, early- to mid-
succession riparian habitat. Historically, flooding was probably the 
main cause of disturbances in the plant's habitat, although wildfire 
and grazing by native herbivores also may have been important. Although 
flowering and fruiting stems may exhibit increased dieback because of 
these events, vegetative rosettes appear to be little affected 
(Mountain West Environmental Services 1985, pp. 2-3). It commonly 
occurs in communities dominated by nonnative and disturbance-tolerant 
native species, including creeping bentgrass (Agrostis stolonifera), 
Kentucky bluegrass (Poa pratensis), American licorice (Glycyrrhiza 
lepidota), Flodman's thistle (Cirsium flodmanii), curlytop gumweed 
(Grindelia squarrosa), and smooth scouring rush (Equisetum laevigatum). 
Its habitat on Warren Air Force Base (AFB) includes wet meadow zones 
dominated by switchgrass (Panicum virgatum), mat muhly (Muhlenbergia 
richardsonis), little bluestem (Schizachyrium scoparium), prairie 
cordgrass (Spartina pectinata), and other native grasses. All of these 
habitat types are usually intermediate in moisture, ranging from wet, 
streamside communities dominated by sedges, rushes, and cattails to 
dry, upland prairie habitats (Fertig 1998a, pp. 2-4).
    Typically, Colorado butterfly plant habitat is open, without dense 
or woody vegetation. The establishment and survival of seedlings 
appears to be enhanced at sites where tall and dense vegetation has 
been removed by some form of disturbance. In the absence of occasional 
disturbance, the plant's habitat can become choked by dense growth of 
willows, grasses, and exotic plants (Fertig 1996, p. 12). This prevents 
new seedlings from becoming established and replacing plants that have 
died (Fertig 1996, pp. 12-14).
    For the purposes of this analysis, we consider all occurrences of 
the Colorado butterfly plant within the same 12-digit HUC watershed to 
be one population. Populations defined this way typically consist of 
numerous subpopulations, each with dozens to hundreds of flowering 
stems and rosettes. These subpopulations are often widely scattered, 
which contributes to this species' resiliency and redundancy. There are 
no data (e.g., genetic relatedness) available to more precisely define 
populations, and although distance of 1 kilometer (km) (0.6 miles (mi)) 
or greater may exceed the distance traveled by pollinators, it is 
possible that seeds may disperse over much greater distances (Heidel 
2016, pers. comm.). Therefore, because these gaps are probably too 
small to prevent the dispersal of pollinators and/or seeds between 
subpopulations, colonies along the same stream reach (12-digit HUC) 
should be considered part of the same population. This approach to 
grouping populations varies from the characterization of populations in 
both the listing decision (65 FR 62302; October 18, 2000) and critical 
habitat designation (70 FR 1940; January 11, 2005), where populations 
were defined by landowner and/or proximity within a drainage. We find 
organizing populations based on 12-digit HUCs to more accurately 
describe components of population ecology (genetic exchange within a 
geographic area), and stressors affecting the species tend to vary by 
watershed. Because of this new organization of population structure, 
some populations considered distinct and separate during the 2000 
listing decision are now combined and vice versa, although many 
populations are the same in this final rule as they were presented in 
the 2000 listing rule.

Population Abundance and Trends

    The Colorado butterfly plant occurred historically and persists in 
various ecological settings described above under Habitat Description, 
including wet meadows, stream channels, stream floodplains, and spring-
fed wetlands. A detailed summary of the status of the species between 
1979 and 2016 is provided in the species' biological report (USFWS 
2017a, pp. 13-22).
    In 1998 and 1999, in preparation for our listing determination for 
the species, the rangewide census of flowering individuals was 
estimated at 47,300 to 50,300, with the majority of these occurring in 
Wyoming (Fertig 1998a, p. 5; Fertig 2000, pp. 8-13). However, a 
population was discovered in Colorado in 2005 that had a peak census of 
26,000 plants in 2011, bringing the total rangewide population to 
approximately 73,300 to 76,300 plants over time. In 2016, another 
population was discovered in a different 12-digit HUC upstream of known 
populations on Horse Creek in Laramie County, Wyoming, with only 17 
individuals, although the area had just been hayed and was likely an 
incomplete representation of the total number of plants in this 
population (USFWS 2016b, entire). Discovery of new populations suggests 
this species is faring better than presumed at the time of listing.
    Average numbers may be a more appropriate way to represent 
populations than the minimum and maximum values, although all provide 
insight into the population's resiliency, or the ability to withstand 
stochastic events. The number of reproductive individuals in a 
population is somewhat driven by environmental factors and is shown to 
vary considerably, so understanding the variability in the number of 
individuals present in any given year is meaningful in assessing 
population resiliency. Population numbers have fluctuated five-fold 
over the course of the longest-running monitoring study (28 years) 
conducted on Warren AFB. There, the population peaked at over 11,000 
flowering plants in 1999 and 2011, making it one of the largest 
populations rangewide, and then dropped to 1,916 plants in 2008 (Heidel 
et al. 2016, p. 1). The Warren AFB population numbers provide some 
indication of how population numbers can vary in landscapes not managed 
for agricultural purposes, and it is likely that numbers vary even more 
dramatically on managed landscapes. If this fluctuation was applied to 
the rangewide population estimates above, then total rangewide numbers 
for average years might be less than 50 percent of rangewide estimates 
in favorable years (Handwerk 2016, pers. comm.; Heidel 2016, pers. 
comm.).
    The final listing rule (65 FR 62302; October 18, 2000) defined 
large populations as those containing more than 3,000 reproductive 
individuals, moderate containing 500 to 2,500 reproductive individuals, 
and small having fewer than 200 reproductive individuals (no 
populations contained 200 to 500 plants or 2,500 to 3,000 plants), and 
so characterized the species as being represented by 10 large stable or 
increasing populations, 4 moderate extant but declining populations, 3 
likely small populations, and 9 likely extirpated populations. However, 
after monitoring roughly half the known populations annually for the 
past 14 years, we understand that population size can fluctuate 
significantly from year to year; therefore, population size in any 
given year is not a good indicator of resiliency. Individual 
populations exhibit substantial stochasticity, with localized 
extirpation and recolonization based on disturbances. Therefore, our 
estimates of resiliency are now based on

[[Page 59574]]

averages of population censuses over multiple years and trends of 
populations in response to management and stressors. Resiliency is 
based on the average number of reproductive individuals within the 
survey area (generally having more than 100 reproductive individuals 
most years indicates high resiliency, between 50 and 100 is moderate, 
and under 50 is low), trends in population numbers where available, and 
response to stochastic events. Based on this, we now have 15 high 
resiliency populations, 2 moderate resiliency populations, 6 low 
resiliency populations, 2 populations with unknown resiliency, and 
records of 6 extirpated populations. Additionally, there are three 
introduced populations that do not contribute to recovery and were not 
assessed for resiliency, representation, or redundancy.

Colorado

    The Colorado butterfly plant is known to occur in Adams, Boulder, 
Douglas, Jefferson, Larimer, and Weld Counties in northern Colorado, 
spanning 12 12-digit HUC watersheds (see figure above). Six historical 
occurrences have not been documented since 1984, and are presumed 
extirpated.
    The majority of Colorado butterfly plants in Colorado are located 
on lands managed by the City of Fort Collins Natural Areas Department 
(CFCNAD) in Weld and Larimer Counties. The plants are distributed among 
three distinct habitats on either side of Interstate 25 and have 
numbered between 3 to more than 26,000 reproductive individuals. These 
areas are being managed to maintain suitable habitat for the species 
(CFCNAD 2008, p. 1; CFCNAD 2010, p. 1; CFCNAD 2011a, entire; CFCNAD 
2011b, entire; CFCNAD 2014, entire). Annual census information on 
flowering individuals at the Meadow Springs Ranch in Weld County 
indicates that the large fluctuations in population numbers are 
actually around a stable mean (744 flowering plant average, median of 
140, range of 45-2,719 flowering plants). Other populations in Colorado 
have not been routinely monitored; consequently, no trend information 
is available (USFWS 2016b, entire). In summary, the species is 
represented in Colorado by two high resiliency populations that 
contribute to species redundancy and three low resiliency populations 
with minimal contribution to species redundancy.

Nebraska

    Populations of the Colorado butterfly plant in Nebraska are 
considered at the edge of the species' range (65 FR 62302, October 18, 
2000). In 1985, monitoring along Lodgepole Creek in extreme eastern 
Wyoming and Kimball County, Nebraska, found 2,065 individual plants in 
six subpopulations. Surveys conducted in 1985, along Lodgepole Creek 
near the Nebraska/Wyoming border in Kimball County, found just over 
2,000 flowering plants (Rabbe 2016, pers. comm). A later survey in 1992 
found two populations of Colorado butterfly plant: one population (547 
plants) along Lodgepole Creek and one population (43 plants) at Oliver 
Reservoir State Recreation Area (SRA) in the southwest panhandle of 
Nebraska in Kimball County west of the city of Kimball, Nebraska 
(Fertig 2000a, p. 12). Survey results from 2004 suggested the species 
was extirpated from the State (Fritz 2004, pers. comm.). However, a 
2008 survey within three 12-digit HUC watersheds, along 13 km (8 mi) of 
historically occupied habitat and the Oliver Reservoir SRA, located 12 
plants in four locations on private lands along Lodgepole Creek: 5 
plants in areas where the species had been located before and 7 plants 
in areas newly watered by a landowner piping water into Lodgepole Creek 
from a cattle stock tank. No plants were found at the Oliver Reservoir 
SRA (Wooten 2008, p. 4). These areas have not been surveyed since 2008. 
Outside of these occurrences, no other populations of the species are 
known to occur in Nebraska (Rabbe 2016, pers. comm.). In summary, due 
to the low abundance, dewatering, over-grazing, and poor habitat 
quality, the species is represented in Nebraska by three populations 
with low resiliency that provide minimal contribution to species 
redundancy.

Wyoming

    Extant populations of Colorado butterfly plant in Wyoming occur 
throughout most of Laramie County and extend northward into Platte 
County (USFWS 2012, pp. 11-21), spanning 17 12-digit HUC watersheds. 
Over 90 percent of known occurrences in Wyoming are on private lands, 
with parts of two occurrences on State school trust lands, all of a 
third occurrence on State lands, and one occurrence on Federal lands. 
Populations in Wyoming that are found partly or fully on State school 
trust lands are managed for agricultural uses.
    The population on Federal lands occurs on Warren AFB located 
adjacent to Cheyenne provides information on species trends as it may 
have occurred prior to human settlement of the area (with wild grazers 
and natural streamflow), and represents the level of hydrological 
complexity of three different sizes of streams. The highest census 
numbers at Warren AFB totaled over 11,000 plants in 1998 and 2011, and 
the mean census numbers for all other years have remained at or above 
50 percent of that peak, based on 1988-2016 numbers (Heidel et al. 
2016, pp. 11-14). In terms of genetic representation, a study conducted 
on Colorado butterfly plants occupying three drainages at Warren AFB 
found that one of the drainages was genetically unique and more diverse 
than the other two drainages (Floyd 1995, pp. 73-81), but that overall 
population-level genetic diversity was low. Another study at Warren AFB 
found that plants in one of the drainages contained unique alleles, 
sharing genetic composition with only a small number of individuals 
from the second and no individuals of the third drainage, indicating 
fine-scale genetic variability within that portion of the species' 
range (Tuthill and Brown 2003, p. 251). Assuming similar genetic 
structure across the species' range, this suggests a high degree of 
genetic representation at the species level. This genetic information, 
however, does not provide sufficient strength in terms of sample size 
in discerning populations from each other.
    Since 2004, the Service has had agreements with 11 private 
landowners within six 12-digit HUC watersheds in Laramie County, 
Wyoming, and one watershed in Weld County, Colorado (described in 
detail under Conservation Efforts, below), to conduct annual monitoring 
of the Colorado butterfly plant. We also provide management 
recommendations to help landowners maintain habitat for the species. 
Many of the landowners graze cattle or horses where the species occurs; 
others use the areas for haying operations. For example, one population 
was heavily grazed for over a decade, leading to counts of fewer than 
30 reproductive individuals for several years, but when the grazing 
pressure was relieved, the population rebounded within 1 year to more 
than 600 reproductive individuals (USFWS 2016b, entire). This outcome 
may indicate that either a robust seedbank was present or vegetative 
rosettes avoided the intense grazing pressure and bolted after grazing 
diminished. The total number of plants counted in Wyoming under these 
agreements between 2004 and 2018 has varied from approximately 1,000 to 
over 21,000 reproductive individuals. Combining annual census numbers 
from all monitored populations in Wyoming, we have observed small to 
extreme population fluctuations, and some populations jumped from 
having few or no flowering plants in one year to

[[Page 59575]]

having hundreds or even thousands the following year (USFWS 2012, pp. 
11-21; USFWS 2016, entire). Wyoming is represented by 13 highly 
resilient populations that contribute to species redundancy, 2 
moderately resilient populations that contribute to species redundancy, 
and 2 populations with unknown resiliency and redundancy due to lack of 
information.

Conservation Efforts

    The listing decision (65 FR 62302, October 18, 2000, p. 62308) 
stated that ``[i]n order for a population to sustain itself, there must 
be enough reproducing individuals and sufficient habitat to ensure 
survival of the population. It is not known if the scattered 
populations [of the Colorado butterfly plant] contain sufficient 
individuals and diversity to ensure their continued existence over the 
long term.'' Today, we understand that, regarding ecological 
representation, the species is characterized by having at least one 
population within each ecological setting and within all but the 
southern-most portions of the historical range. Furthermore, most 
populations contain individuals in more than one ecological setting, 
such as individuals along the creek bank and individuals outside of the 
creek bank and in the floodplain of the creek. The Service has not 
typically measured the acreage of suitable habitat at each population 
for a number of reasons, namely because we found the number of 
individuals at the site to be more informative of the population's 
status and because of the wide variation in habitat types occupied by 
the species.
    The Service has worked with partners to protect existing 
populations. Much of this work has been accomplished through voluntary 
cooperative agreements. For example, beginning in 2004, the Service has 
entered into 11 wildlife extension agreements (WEAs) with private 
landowners, representing six of the 12-digit HUCs, to manage riparian 
habitat for Colorado butterfly plant (70 FR 1940; January 11, 2005). 
These 15-year WEAs cover a total of 1,038 hectares (ha) (2,564 acres 
(ac)) of the species' habitat along 59 km (37 mi) of stream. These 
agreements represent approximately one-third of the known populations 
of Colorado butterfly plant in Wyoming and Colorado, including some of 
the largest populations on private lands. All of the landowners have 
agreed to the following:
    (1) Allow Service representatives or their designee access to the 
property for monitoring or fence installation;
    (2) Coordinate hay cutting activities in areas managed primarily 
for hay production to consider the Colorado butterfly plant's seed 
production needs;
    (3) Prevent application of herbicides closer than 30.5 m (100 ft) 
from known subpopulations of the Colorado butterfly plant; and
    (4) Manage livestock grazing activities in conjunction with 
conservation needs of the Colorado butterfly plant.
    One of the landowners signed a 10-year agreement instead of a 15-
year agreement that was renewed for an additional 10 years in 2015. The 
remaining agreements expire in late 2019. All landowners whose 
properties will be included in the post-delisting monitoring program 
when this final rule goes into effect (see DATES, above) are amenable 
to creating new agreements--once the existing agreements expire this 
year--that will last the duration of the post-delisting monitoring.
    One of the benefits of the WEAs for both the Service and private 
landowners is that we can review the population numbers annually and 
together develop management recommendations to improve growing 
conditions for the species. Populations occurring within designated 
critical habitat (see figure, above) have not been surveyed since the 
critical habitat determination surveying in 2004, and their trends, 
threats, and viabilities are uncertain. However, the Wyoming Ecological 
Services Field Office has not consulted under the Act with private 
landowners managing these parcels on any projects that may adversely 
affect the critical habitat for this species. Additionally, we reviewed 
aerial imagery of the critical habitat units and found only two minimal 
changes between 2004 and 2015 (reflecting habitat conditions at the 
time of designation and the most recent aerial imagery available) 
throughout all critical habitat units; these changes affect only a few 
acres of designated critical habitat (USFWS 2017b, entire). 
Consequently, we determine that activities occurring on critical 
habitat are likely the same as they were at the time of designation. 
Furthermore, because many of the private lands included in the critical 
habitat designation are adjacent to lands under WEAs, we determine that 
the populations occurring within designated critical habitat are likely 
stable, and fluctuating similarly to populations on lands that we 
monitor under WEAs. We have no reason to believe that populations 
occurring on designated critical habitat are responding to stressors 
differently than those populations we monitor. Therefore, populations 
throughout the species' range on private, local, and Federal lands 
either have been observed to be, or are highly likely to be, 
fluctuating around a stable population size.
    The Service and the U.S. Air Force signed a memorandum of agreement 
(MOA) on January 18, 1982 (updated in 1999 with the pending listing 
decision, and updated in 2004 with the pending critical habitat 
decision), to facilitate the preservation, conservation, and management 
of the Colorado butterfly plant (USFWS 1982, entire; USFWS 1999, 
entire; USFWS 2004, entire). In 2004, Warren AFB included a 
conservation and management plan for the species in its integrated 
natural resources management plan (CNHP 2004, entire). Through these 
plans, the Service partners with the U.S. Air Force and Wyoming Natural 
Diversity Database to monitor and protect the population of the 
Colorado butterfly plant on the Warren AFB. Conservation actions 
include annual monitoring; nonnative, invasive species control and 
eradication; and maintenance of appropriate floodplain characteristics 
for the species. Based on 29 years of monitoring and management, the 
population of the Colorado butterfly plant on the Warren AFB is doing 
well, with some areas declining while others are increasing (Heidel et 
al. 2016, entire).
    Three populations in Larimer and Weld Counties, Colorado, occur on 
properties owned by the City of Fort Collins, and two are among the 
largest across the species' range. The City of Fort Collins developed a 
10-year master plan for the Natural Areas Department in 2014, which 
provides a framework for the conservation and preservation of natural 
areas, including the populations of the Colorado butterfly plant. The 
master plan prescribes conservation actions that allow for the 
persistence of the Colorado butterfly plant on the landscape (CFCNAD 
2016a, entire), including prescribed burns to eliminate competition, 
managed grazing to maintain early successional habitat, and improved 
security of water flow to the species' habitat to ensure the necessary 
subirrigation is available for populations of Colorado butterfly plant.
    Populations of Colorado butterfly plant are not known to occur on 
lands managed by the Bureau of Land Management (BLM) at this time, 
although there is potential for populations to be discovered on BLM 
lands in the future. Because of this possibility, the Service and BLM 
in Wyoming have developed conservation measures under a Statewide 
programmatic consultation under section 7 of the Act for the Colorado 
butterfly plant. These conservation

[[Page 59576]]

measures are incorporated into BLM's 2008 Record of Decision and 
Approved Rawlins Resource Management Plan (RMP; BLM 2008, entire) and 
include, but are not limited to: (1) Buffering individuals and 
populations by 800 m (0.5 mi); (2) implementing standards for healthy 
rangelands and guidelines for livestock grazing management for the 
public lands administered by BLM in the State of Wyoming; (3) limiting 
the number of grazing animals within the permit area; and (4) 
protecting surface water through prohibiting surface development in the 
following areas: within 400 m (0.25 mi) of the North Platte River; 
within 152 m (500 ft) of live streams, lakes, reservoirs, and canals 
and associated riparian habitat; and within 152 m (500 ft) of water 
wells, springs, or artesian and flowing wells (BLM 2005, pp. 4-2 
through 4-4). The newly discovered population on Wild Horse Creek (WY-
23) occurs within the agreement area that BLM developed with the 
landowners, and so the conservation measures included in the Rawlins 
RMP are applied to this population.
    In summary, these agreements and plans have provided useful data, 
facilitated good management of nine of the largest and most resilient 
populations, and resulted in stable or increasing population trends. 
Because of the information we obtained through these agreements and 
plans, we are able to understand the resiliency of individual plants 
and populations, the representation of the species within its 
ecological settings, and the redundancy of the plant population numbers 
and potential for connectivity.

Summary of Changes From the Proposed Rule

    We have made updates to our discussions of the species' population 
status (including 2018 information) and factors affecting the species, 
based on comments submitted by the public and information provided to 
us by peer reviewers, as discussed later in this final rule.

Summary of Factors Affecting the Species

    Section 4 of the Act and its implementing regulations (50 CFR part 
424) set forth the procedures for listing species, reclassifying 
species, or removing species from listed status. ``Species'' is defined 
by the Act as including any species or subspecies of fish or wildlife 
or plants, and any distinct vertebrate population segment of fish or 
wildlife that interbreeds when mature (16 U.S.C. 1532(16)). A species 
may be determined to be an endangered or threatened species due to one 
or more of the five factors described in section 4(a)(1) of the Act: 
(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.
    Determining whether the status of a species has improved to the 
point that it can be downlisted (i.e., reclassified from endangered to 
threatened) or delisted requires consideration of whether the species 
is an endangered species or threatened species because of the same five 
categories of threats specified in section 4(a)(1) of the Act. For 
species that are already listed as endangered species or threatened 
species, this analysis of threats is an evaluation of both the threats 
currently facing the species and the threats that are reasonably likely 
to affect the species in the foreseeable future following the delisting 
or downlisting and the removal or reduction of the Act's protections.
    A species is an ``endangered species'' for purposes of the Act if 
it is in danger of extinction throughout all or a significant portion 
of its range and is a ``threatened species'' if it is likely to become 
an endangered species within the foreseeable future throughout all or a 
significant portion of its range. The word ``range'' in the significant 
portion of its range phrase refers to the range in which the species 
currently exists, and the word ``significant'' refers to the value of 
that portion of the range being considered to the conservation of the 
species. We consider ``foreseeable future'' as that period of time 
within which a reliable prediction can be reasonably relied upon in 
making a determination about the future conservation status of a 
species (DOI Solicitor M-37021; January 16, 2009). We consider 15 to 20 
years to be a reasonable period of time within which reliable 
predictions can be made for the Colorado butterfly plant. This time 
period includes at least five generations of the species, coincides 
with management timeframes in renewed WEAs, and aligns with the 
timeframes for predictions regarding municipal development and growth 
in the area. For the purposes of this analysis, we first evaluate the 
status of the species throughout all of its range, then consider 
whether the species is in danger of extinction or likely to become so 
in any significant portion of its range.
    In considering what factors might constitute threats, we must look 
beyond the exposure of the species to a particular factor to evaluate 
whether the species may respond to the factor in a way that causes 
actual impacts to the species. If there is exposure to a factor, but no 
response, or only a positive response, that factor is not a threat. If 
there is exposure to a factor and the species responds negatively, the 
factor may be a threat, and we attempt to determine how significant a 
threat it is. If the threat is significant it may drive, or contribute 
to, the risk of extinction of the species such that the species 
warrants listing as an endangered species or a threatened species as 
those terms are defined by the Act. This does not necessarily require 
empirical proof of a threat. The combination of exposure and some 
corroborating evidence of how the species is likely impacted could 
suffice. The mere identification of factors that could impact a species 
negatively is not sufficient to compel a finding that listing is 
appropriate; we require evidence that these factors individually or 
cumulatively are operative threats that act on the species to the point 
that the species meets the definition of an endangered species or 
threatened species under the Act.
    The Colorado butterfly plant is federally listed as threatened. 
Below, we present a summary of threats affecting the species and its 
habitats in the past, present, and predicted into the future. A 
detailed evaluation of factors affecting the species at the time of 
listing can be found in the listing determination (65 FR 62302; October 
18, 2000) and designation of critical habitat (70 FR 1940; January 11, 
2005). An evaluation of factors affecting the species after 2005 can be 
found in the 2012 5-year review (USFWS 2012, entire). The primary 
threats to the species identified at the time of listing include 
overgrazing by cattle or horses, haying or mowing at times of the year 
incompatible with Colorado butterfly plant reproduction, habitat 
degradation resulting from vegetation succession or urbanization of the 
habitat, habitat conversion to cropland or subdivision, water 
development, herbicide spraying, and competition with exotic plants (65 
FR 62302; October 18, 2000). Since the time of listing, oil and gas 
development and climate change have become potential threats to this 
species and are analyzed under Factor A and Factor E, respectively, 
below. The 2012 5-year review evaluated all potential threats to this 
species and found that all threats presented at a low overall level to 
the species (USFWS 2012, Appendix A) and

[[Page 59577]]

that the species had a high recovery potential (USFWS 2012, p. 39). In 
2016, a revised 5-year review did not recommend delisting, but 
recommended a formal evaluation of whether the species needed to remain 
listed (USFWS 2016, p. 40). As a result, we completed a biological 
report the following year, which concluded that the species had 
moderate to high viability based on its resiliency, redundancy, and 
representation (USFWS 2017a, p. 33).

A. The Present or Threatened Destruction, Modification, or Curtailment 
of Its Habitat or Range

Residential, Urban, and Energy Development
    At the time of listing (65 FR 62302; October 18, 2000), residential 
and urban development around the cities of Cheyenne and Fort Collins 
were identified as past causes of habitat conversion and habitat loss 
to the Colorado butterfly plant; these types of development were not a 
concern in Nebraska at the time of listing nor are they now. Although 
difficult to quantify because land conversion was not tracked during 
the settlement of the West, likely a few hundred acres of formerly 
suitable habitat were converted to residential and urban sites, 
contributing to loss of habitat (Fertig 1994, p. 38; Fertig 2000a, pp. 
16-17). Much of the species' range occurs along the northern Front 
Range of the Rocky Mountains in Colorado and Wyoming, which has 
experienced dramatic growth in the recent past and is predicted to grow 
considerably in the future (Regional Plan Association 2016, entire), 
particularly in Larimer and Weld Counties in Colorado (University of 
Colorado Boulder 2016, pp. 119-120). The demand that urban development 
places on water resources also has the ability to dewater the streams 
and lower groundwater levels required by the species to maintain self-
sustaining populations, and is explored below.
    The two large populations of the Colorado butterfly plant in 
Larimer and Weld Counties, Colorado, occur on lands managed as open 
space by CFCNAD, and are not directly subject to residential or urban 
development. Consequently, despite projected increases in human density 
and urban development along the northern Front Range, these lands are 
managed to allow for the persistence of these populations, with managed 
grazing or burning (CFCNAD 2016b, entire). CFCNAD does not own all 
mineral rights on these lands; therefore, sensitive areas within these 
boundaries may be impacted by mineral development. However, in light of 
this potential threat, CFCNAD completed a planning process in which 
they highlighted areas to be avoided by mineral development (The Nature 
Conservancy 2013, entire). While oil and gas development has increased 
in northern Colorado and southeastern Wyoming since the time of 
listing, no oil or gas wells have been proposed or likely will be 
proposed in areas that will directly or indirectly impact populations 
of the Colorado butterfly plant in Colorado or in Wyoming, particularly 
due to the species' occurrence in riparian and wetland habitats. 
Because the plant occurs in riparian and wetland habitats that 
routinely flood, it is likely that oil and gas wells will be sited 
outside of population boundaries. While there is potential for indirect 
effects through spills or sedimentation, we have no specific 
information about those effects on the species to date.
    According to publicly available information, there are no current 
proposals for urban or residential development on lands containing 
populations of Colorado butterfly plant in Wyoming. Monitoring of lands 
under agreement (CFCNAD, WEAs, and Warren AFB) has also shown that 
neither urbanization nor conversion to intensive agricultural 
activities has occurred as predicted in the final listing rule (65 FR 
62302, October 18, 2000; USFWS 2012, pp. 11-22; USFWS 2016b, entire). 
Monitoring data over the past 29 years at WAFB have shown that 
populations remain stable without being managed for agricultural 
purposes, although numbers of reproductive individuals fluctuate during 
any given year (Heidel et al. 2016, pp. 14-18). Since the time of 
listing, the Service has received few requests for consultation under 
section 7 of the Act for projects that may adversely affect this 
species. Informal consultations have been limited to grazing, power 
lines, pipelines, road development, and drainage crossing projects, and 
avoidance and minimization of potential impacts has been readily 
achieved (USFWS 2017c, entire).
    Furthermore, chapters 3 and 4 of the Laramie County Land Use 
Regulations address floodplain management and require specific 
provisions and permits for construction within floodplains (Laramie 
County 2011, pp. 165-185), which encompass all Colorado butterfly plant 
habitat within the county; therefore, these regulations extend some 
level of protection to the species and its habitat. These regulations 
are in place to ``promote public health, safety, and general welfare 
and to minimize public and private losses due to flood conditions'' 
(Laramie County 2011, p. 165), and are a common-sense approach to 
protecting many resources, including the Colorado butterfly plant and 
its habitat, by limiting development in the floodplains. These 
regulations are discussed in detail under Factor D, below.
    The threats of residential and urban development, once considered 
significant threats to the Colorado butterfly plant, have been largely 
avoided because most development has occurred outside of the habitat in 
which this species occurs. Annual monitoring conducted by the Service 
since 2004 indicates that populations are stable and unaffected by any 
development that has occurred within the species' range. While human 
population growth and development are predicted for the Front Range of 
the Rocky Mountains in Colorado into the future, these areas are 
outside of the species' occupied habitat, and we do not anticipate 
development in the protected areas under management of CFCNAD, and do 
not anticipate development due to continued restrictions against 
development within the floodplain. Additionally, increases in oil and 
gas development in northern Colorado and southeastern Wyoming have not 
directly or indirectly impacted populations of the Colorado butterfly 
plant and are not likely to do so in the future. Current ownership and 
management by CFCNAD and Warren AFB of lands containing a majority of 
large populations of the Colorado butterfly plant protect the species 
from current and future impacts due to residential, urban, and energy 
development.
Agricultural Practices
    At the time of listing (65 FR 62302; October 18, 2000), conversion 
of grassland to farmlands, mowing grasslands, and grazing were 
considered threats to the Colorado butterfly plant. Prior to listing, 
the conversion of moist, native grasslands to commercial croplands was 
widespread throughout much of southeastern Wyoming and northeastern 
Colorado (Compton and Hugie 1993, p. 22), as well as in Nebraska. 
However, conversion from native grassland to cropland has slowed 
throughout the species' range since the time of listing, with no lands 
converted in Laramie County and just 12 ha (30 ac) converted in Platte 
County between 2011 and 2012 (FSA 2013, entire).
    Mowing for hay production was identified as a threat at the time of 
listing, if conducted at sensitive times of year for Colorado butterfly 
plant (prior to seed maturation) (Fertig 1994, p. 40; USFWS 1997, p. 
8). However,

[[Page 59578]]

monitoring by the Service over the past 13 years indicates that mowing 
prior to seed maturation occurs infrequently. Even in areas where early 
season mowing has occurred, annual monitoring has shown high numbers of 
reproductive plants present in subsequent years, suggesting that mowing 
for hay production is not a threat to the species (USFWS 2016b, 
entire).
    The agricultural practices of grazing and herbicide application 
threatened the Colorado butterfly plant at the time of listing. 
However, since then, the Service has made and continues to make 
recommendations to cooperating landowners on agricultural management 
that fosters resiliency in populations of the species. We determined 
that these measures have decreased the severity of these stressors. We 
also anticipate that landowners will continue their current 
agricultural practices into the future, based on the data we have 
collected from WEAs (USFWS 2016b, entire) and analysis of aerial 
imagery of designated critical habitat (USFWS 2017b, entire). Through 
these agreements, we also learned that the species is highly adapted to 
withstand stochastic events. Therefore, we do not rely on the 
implementation of the WEAs to ensure that the species remains highly 
resilient because the WEAs simply provided a mechanism for the Service 
to gain information to better understand its viability. Because of this 
information regarding resiliency, redundancy, and representation, we 
believe the plant will continue to thrive when the species is delisted 
and the protections of the Act are removed. Grazing is further explored 
under Factor C, below, and herbicide spraying is further explored under 
Factor E, below.
Water Management
    At the time of listing (65 FR 62302; October 18, 2000), water 
management (actions that move water to croplands, such as irrigation 
canals, diversions, and center pivot irrigation development) was 
considered a threat that would remove moisture from Colorado butterfly 
plant habitat. The management of water resources for livestock 
production and domestic and commercial human consumption, coupled with 
increasing conversion of lands for agricultural production, often led 
to channelization and isolation of water resources; changes in 
seasonality of flow; and fragmentation, realignment, and reduction of 
riparian and moist lowland habitat (Compton and Hugie 1993, p. 22). All 
of these actions could negatively impact suitable habitat for the 
species.
    Dewatering portions of Lodgepole Creek in Kimball County, Nebraska, 
has led to the extirpation of some of the species' known historical 
populations there, and low likelihood of long-term resiliency for the 
two extant populations last monitored in 2008 (Rabbe 2016, pers. 
comm.). Extant populations in Nebraska continue to be threatened by 
dewatering and overgrazing on private land. However, when water was 
reintroduced to formerly occupied habitat after being absent for more 
than 10 years, a population was rediscovered (Wooten 2008, p. 4). While 
rediscovery of this population indicates persistence of a viable 
seedbank for at least 10 years, numbers of plants within the population 
declined from over 600 plants (Fertig 2000a, p. 12) to 12 plants 
(Wooten 2008, p. 4), and the application of water that allowed plants 
to grow was temporary, which suggests the population has a low 
likelihood of long-term resiliency.
    In 2015, the Colorado Water Conservation Board on behalf of CFCNAD 
filed an instream flow right on Graves Creek, the stream that feeds the 
population of Colorado butterfly plants in Soapstone Prairie (CFCNAD 
2016b, entire). This instream flow right was appropriated on January 
26, 2015, and allows for 0.17 cubic feet per second, year-round, which 
will protect and maintain subirrigation of this large and important 
population for CFCNAD through ensuring adequate water availability to 
the species throughout the year.
    The entire range of the Colorado butterfly plant occurs within the 
Platte River Basin. Water usage in the Platte River system is managed 
collaboratively by the States of Colorado, Wyoming, and Nebraska, and 
the Department of the Interior, through the Platte River Recovery 
Implementation Program (PRRIP; PRRIP 2019). The PRRIP, which has been 
in existence since 1997, provides a mechanism for existing and new 
water users and water-development activities in the Platte River Basin 
to operate in regulatory compliance with the Act regarding potential 
impacts to the five Platte River ``target species'' in Nebraska: 
whooping crane (Grus americana), interior least tern (Sterna (Sternula) 
antillarum), northern Great Plains population of piping plover 
(Charadrius melodus), pallid sturgeon (Scaphirhynchus albus), and 
western prairie fringed orchid (Platanthera praeclara). Because the 
PRRIP ensures that shortages to the target flows in the central Platte 
River will be substantially reduced by keeping water within the basin 
more consistently throughout the year, the hydrological component of 
habitat for the Colorado butterfly plant will be maintained at higher 
and more consistent levels than it was prior to the listing of the 
Colorado butterfly plant. The PRRIP also has an adaptive management 
plan to improve management decisions based on information learned. The 
implementation of the PRRIP ensures that more water will stay within 
the Platte River Basin and be available for populations of the Colorado 
butterfly plant.
    In summary, water management can directly and indirectly impact the 
Colorado butterfly plant. While management of water resources has 
negatively impacted the species on a localized scale in the past, there 
is no indication that water management throughout the majority of the 
species' range poses a current threat to the species. Programs and 
policies currently in place, such as the PRRIP and Graves Creek 
instream flow right, provide substantial assurances that the 
hydrological component of currently occupied habitat will remain secure 
and available to populations of Colorado butterfly plant over the long 
term.
Natural Succession and Competition With Nonnative, Invasive Species
    In the absence of periodic disturbance, natural succession of the 
plant community in areas occupied by the Colorado butterfly plant moves 
from open habitats to dense coverage of grasses and forbs, and then to 
willows and other woody species. The semi-open habitats preferred by 
this species can become choked by tall and dense growth of willows; 
grasses; and nonnative, invasive species (Fertig 1994, p. 19; Fertig 
2000a, p. 17). Natural disturbances such as flooding, fire, and native 
ungulate grazing were sufficient in the past to create favorable 
habitat conditions for the species. However, the natural flooding 
regime within the species' floodplain habitat has been altered by 
construction of flood control structures and by irrigation and 
channelization practices (Compton and Hugie 1993, p. 23; Fertig 1994, 
pp. 39-40). Consequently, the species relies on an altered flood regime 
and other sources of disturbance to maintain its habitat.
    In the absence of natural disturbances today, managed disturbance 
may be necessary to maintain and create areas of suitable habitat 
(Fertig 1994, p. 22; Fertig 1996, pp. 12-14; Fertig 2000a, p. 15). 
However, monitoring of the population at Warren AFB indicates that 
populations can persist without natural disturbances such as fire and 
flooding through natural dieback of woody vegetation and native 
ungulate grazing

[[Page 59579]]

(Heidel et al. 2016, pp. 2-5). Additionally, some Federal programs, 
such as those administered by the U.S. Department of Agriculture's 
Natural Resources Conservation Service, focus on enhancing or 
protecting riparian areas by increasing vegetation cover and pushing 
the habitat into later successional stages, which removes the types of 
disturbance the Colorado butterfly plant needs (65 FR 62302; October 
18, 2000, p. 62307). However, these programs are implemented in only a 
small portion of the species' range. The Service learned from 
monitoring the 11 WEA properties that the typical approach of managing 
for livestock grazing, coupled with an altered flood regime, appears to 
provide the correct timing and intensity of disturbance to maintain 
suitable habitat for the species (USFWS 2012, pp. 9-21; USFWS 2016b, 
entire). There has been no noticeable change in general management 
practices (e.g., mowing and grazing) or change in the natural 
succession rate in either the WEA properties or the designated critical 
habitat since the agreements were signed or the critical habitat was 
designated, and we have no reason to believe that these management 
practices or natural succession rates will change in the foreseeable 
future. Therefore, through the information we have gathered since the 
time of listing, it appears that natural succession is not occurring at 
the level previously considered to threaten this species.
    The final listing rule (65 FR 62302; October 18, 2000) included 
competition with exotic plants and noxious weeds as a threat to the 
Colorado butterfly plant. Competition with exotic plants and noxious 
weeds, here referred to as nonnative, invasive species, may pose a 
threat to the Colorado butterfly plant, particularly given the species' 
adaptation to more open habitats. In areas of suitable habitat for 
Colorado butterfly plant, the following plants may become dominant: The 
native coyote willow (Salix exigua); nonnative, invasive Canada thistle 
(Cirsium arvense); and nonnative, invasive leafy spurge (Euphorbia 
esula). Willow, in particular, increases in the absence of grazing or 
mowing. These species can outcompete and displace the Colorado 
butterfly plant, presumably until another disturbance removes competing 
vegetation and creates openings for Colorado butterfly plant seedlings 
to germinate (Fertig 1998a, p. 17). Since 2004, we have monitored 
populations of the Colorado butterfly plant that have slowly decreased 
in numbers or disappeared following the invasion and establishment of 
these other plant species, only to see Colorado butterfly plants return 
to the area following disturbance (USFWS 2016b, entire). Additionally, 
at least one population has moved to an uninvaded area downstream of 
its former invaded habitat (Handwerk 2016, pers. comm.), suggesting 
that populations can find more suitable habitat nearby.
    Prior to listing, biological control agents were used to control 
nonnative, invasive species at Warren AFB and may have depressed 
numbers and extent of Canada thistle and leafy spurge. Introduced gall-
forming flies have slowly become established on Warren AFB and have 
reduced the vigor, height, and reproductive ability of small patches of 
Canada thistle (Fertig 1997, p. 15), at least in some years (Heidel et 
al. 2016, p. 16). Also on the Warren AFB, a biocontrol agent for leafy 
spurge, a different flea beetle than infests the Colorado butterfly 
plant, was observed in 1997 (Fertig 1998b, p. 18). While the effects of 
biocontrol agents on nonnative, invasive species appear promising, we 
do not have sufficient current information on the status of these 
agents.
    Natural succession was considered a threat to the Colorado 
butterfly plant at the time of listing. However, we now understand that 
the altered flood regime of today, coupled with disturbance from fire 
and grazing, is sufficient to maintain suitable habitat throughout much 
of the species' range. Competition with nonnative, invasive species is 
an ongoing stressor for portions of populations, although these 
invasive species tend not to survive the regular disturbances that 
create habitat for the Colorado butterfly plant. Therefore, while 
individuals or populations may be out-competed by native or nonnative, 
invasive species at higher succession levels, periodic disturbance 
maintains or creates new habitats for the Colorado butterfly plant.
Summary of Factor A
    The following stressors warranted consideration as possible current 
or future threats to the Colorado butterfly plant habitat under Factor 
A: (1) Residential, urban, and energy development; (2) agricultural 
practices; (3) water management; and (4) natural succession and 
competition with nonnative, invasive species. However, these stressors 
are either being adequately managed, they have not occurred to the 
extent anticipated at the time of listing, or the species is tolerant 
of the stressor as described above. While these stressors may be 
responsible for loss of historical populations (they have negatively 
affected population redundancy), and are currently negatively affecting 
the populations in Nebraska, we do not anticipate a rangewide increase 
in these stressors in the future, although they will continue at some 
level.

B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    Factor B was not considered a threat to the species at the time of 
listing (65 FR 62302; October 18, 2000). We are aware of three 
unpermitted collections of seeds of the Colorado butterfly plant for 
scientific and/or commercial purposes since the publication of the 
final listing rule. These three collections were limited events that 
occurred at an introduction site in Colorado and from a large, robust 
population in Wyoming. Based on recent population data, these 
unpermitted collection events had no apparent impact on the number and 
distribution of plants within these populations or the species' habitat 
(based on Heidel et al. 2016, p. 13; USFWS 2016b, entire).
    Other than these collections, we are not aware of any attempts to 
use the Colorado butterfly plant for commercial, recreational, 
scientific, or educational purposes. In the future, we do not 
anticipate this species will be collected due to its lack of showiness 
for much of the year and because it occurs in generally inaccessible 
areas.
Summary of Factor B
    At the time of listing, Factor B was not considered a threat to the 
Colorado butterfly plant. We are aware of only three unpermitted 
collections of the seeds of the species since listing. These collection 
events had no apparent effect on the number and distribution of plants 
from which the seeds were taken.

C. Disease or Predation

    The listing of the Colorado butterfly plant (65 FR 62302; October 
18, 2000) did not include threats from disease or predation, although 
livestock grazing was described as a potential threat if grazing 
pressures were high. No diseases are known to affect this species. In 
2007, a precipitous decline in plant numbers was observed in many 
populations monitored in Colorado and Wyoming. The exact cause of the 
decline was not positively identified, but weather and insect herbivory 
were two potential contributing factors. Weather-related impacts 
included an early start to the growing season, lower than normal spring 
precipitation levels (which were magnitudes lower than in all previous 
years), and higher mean temperatures in late summer. Insect

[[Page 59580]]

herbivory also was suspected, as virtually all reproductive plants were 
riddled with holes, flowering/fruit production was curtailed or greatly 
reduced on all plants, and some bolted plants died before flowering; 
interestingly, no vegetative plants showed evidence of herbivory 
(Heidel et al. 2011, pp. 284-285). Flowering plant numbers remained low 
or declined further in 2008. Surveyors identified one or more flea 
beetle species that may have been responsible for the herbivory. The 
likely flea beetle species (Altica foliaceae) is a native species, and 
its numbers are not known to be affected by human causes.
    Insect herbivory may not be a severe or immediate threat to 
Colorado or Wyoming populations as the impacted populations mentioned 
above rebounded to pre-infestation numbers in 2009 and 2010 (Heidel et 
al. 2011, p. 286). However, insect herbivory may be episodic and 
potentially tied to climate; preliminary tests have been run on insect 
herbivory's potential impact on population resiliency (Heidel et al. 
2011, p. 286). For example, in 2014, intense herbivory from flea 
beetles at Soapstone Prairie and Meadow Springs Ranch resulted in high 
mortality and a reduction in bolting of vegetative rosettes (Strouse 
2017, pers. comm.), and numbers of reproductive individuals in those 
populations were low in 2015 and 2016. We found that these populations 
rebounded in 2017 to record numbers, in the same way populations 
rebounded after the 2007 flea-beetle-caused decline. This herbivory has 
not been reported for the Nebraska populations, although it is possible 
that similar insect herbivory influenced 2008 survey results in 
Nebraska.
    Colorado butterfly plant is highly palatable to a variety of insect 
and mammalian herbivores including Gaura moth (Schinia gaurae), cattle, 
horses, and pronghorn (Antilocapra americana), but the plant appears to 
have some capacity to compensate for herbivory by increasing branch and 
fruit production (Fertig 1994, p. 6; Fertig 2000a, p. 17). Livestock 
grazing can be a threat at some sites if grazing pressures are high due 
to animals not being rotated among pastures or if use is concentrated 
during the summer flowering and fruiting period. Additionally, plants 
may be occasionally uprooted or trampled by livestock and wildlife. In 
at least two locations where a population was divided by a fence, the 
heavily grazed side of the fence had few or no Colorado butterfly 
plants, while the ungrazed side had many (Marriott 1987, p. 27; USFWS 
2016b, entire).
    Heavy grazing at some times of the year may be detrimental to 
Colorado butterfly plant populations by temporarily removing 
reproductive individuals from a population and eliminating seed 
production for that year. However, even after many years of intensive 
grazing, populations have rebounded upon relief (USFWS 2012, pp. 11-21; 
USFWS 2016b, entire). This response is likely due to survival of 
nonreproductive individuals and recruitment from the seedbank. Moderate 
grazing acts as a disturbance that keeps the habitat in an open or 
semi-open state suitable for this species, and light to medium grazing 
can provide benefits by reducing the competing vegetative cover and 
allowing seedlings to become established (USFWS 1997, p. 8).
Summary of Factor C
    In general, while disease or predation has had an occasional 
negative impact on individuals and localities, most of these impacts do 
not appear to affect entire populations, nor do these impacts persist 
for any extended period of time. Individuals are resilient to damage; 
vegetative plants (basal rosettes) appear to be resistant to damage 
from grazing activities and are capable of withstanding stochastic 
events, and reproductive plants send out additional flowering branches 
upon injury. Also, the lack of any known diseases affecting the species 
and the species' redundancy of many populations distributed across most 
of the historical range would likely provide a buffer to any type of 
catastrophic disease outbreak.

D. The Inadequacy of Existing Regulatory Mechanisms

    Under this factor, we examine whether the stressors identified 
within the other factors may be ameliorated or exacerbated by an 
existing regulatory mechanism or conservation efforts. Section 
4(b)(1)(A) of the Act requires the Service to take into account ``those 
efforts, if any, being made by any State or foreign nation, or any 
political subdivision of a State or foreign nation, to protect such 
species.'' In relation to Factor D under the Act, we interpret this 
language to require the Service to consider relevant Federal, State, 
and Tribal laws, regulations, and other such binding legal mechanisms 
that may ameliorate or exacerbate any of the threats we describe in 
threats analyses under the other four factors, or otherwise enhance 
conservation of the species. Our consideration of these mechanisms is 
described in detail within each of the threats or stressors to the 
species (see discussion under each of the other factors).
    For currently listed species, we consider the adequacy of existing 
regulatory mechanisms to address threats to the species absent the 
protections of the Act. Therefore, we examine whether other regulatory 
mechanisms would remain in place if the species were delisted, and the 
extent to which those mechanisms would continue to help ensure that 
future threats will be reduced or minimized.
    In our discussion under Factors A, B, C, and E, we evaluate the 
significance of threats as mitigated by any conservation efforts and 
existing regulatory mechanisms. Where threats exist, we analyze the 
extent to which conservation measures and existing regulatory 
mechanisms address the specific threats to the species. Regulatory 
mechanisms, if they exist, may reduce or eliminate the impacts from one 
or more identified threats. Presently, the Colorado butterfly plant is 
a Tier 1 species in the Plants of Greatest Conservation Need in 
Colorado (Colorado SWAP 2015, entire), and the species is listed on the 
State endangered species list for Nebraska, and will continue to be so 
designated due to the species' extreme rarity in Nebraska (Wooten 2008, 
p. 1).
    When we listed the Colorado butterfly plant in 2000 (65 FR 62302; 
October 18, 2000), the majority of known populations occurred on 
private lands managed primarily for agriculture, with one population at 
Warren AFB, and a few other populations throughout the species' range 
under various local jurisdictions. The listing decision described the 
species' status as Sensitive by the U.S. Forest Service, although no 
populations occurred on Forest Service lands at the time. The listing 
decision also described the lack of protection extended to the Colorado 
butterfly plant through the Federal threatened status of Preble's 
meadow jumping mouse (Zapus hudsonius preblei) that occurs in the same 
range of habitats due to the two species' use of differing successional 
stages of riparian habitats (65 FR 62302, October 18, 2000, p. 62307).

[[Page 59581]]

    Today, the population on Warren AFB represents one of the largest 
and most highly resilient populations of the species; it is managed 
under an integrated natural resources management plan (Warren AFB 2017, 
entire) and a conservation and management plan under Air Force 
Information 32-7064 (CNHP 2004, entire). These plans call for annual 
monitoring, protection and maintenance, and research on threats and 
genetic variability of the population located there. Additionally, a 
Service employee is stationed at Warren AFB to manage its natural 
resources, which includes management of the Colorado butterfly plant 
and its habitat, such as directing herbicide application in the 
vicinity of the species' habitat. A Service employee will maintain this 
role at Warren AFB after delisting of the Colorado butterfly plant.
    The population of the Colorado butterfly plant at Warren AFB has 
been monitored since before listing to determine population trends, 
detect any changes in its habitat, pursue viability assessment, and 
assess population response to different hydrological conditions. The 
monitoring results indicate that plant numbers fluctuate depending on 
climate and hydrology, and the Colorado butterfly plant seems to be 
capable of rebounding after extreme stochastic events such as the flea 
beetle infestation of 2007 (Heidel et al. 2016, pp. 15-17). Upon 
delisting (see DATES, above), when the protections of the Act are 
removed from the Colorado butterfly plant, the Warren AFB management 
plans will maintain protections for this plant, at least until the next 
plan revisions, which have yet to be scheduled. Additionally, the 
species will continue to be managed and monitored as part of the post-
delisting monitoring plan.
    Discovery and subsequent protection of large populations of the 
Colorado butterfly plant on lands owned and managed by CFCNAD are an 
important addition to conservation of the species after it was listed 
in 2000. The regulatory protections that these two populations receive 
from occurring on municipal natural areas lands include indefinite 
protections of land and water and restoration and rehabilitation of 
land and natural systems to build ecological diversity and permanence 
(City of Fort Collins 2014, pp. 1-2). Populations managed by CFCNAD are 
afforded protection from oil and gas development (The Nature 
Conservancy 2013, entire) and from water withdrawals (CFCNAD 2016b, 
entire), and are discussed above under Factor A. Also, as mentioned in 
``Residential, Urban, and Energy Development'' under Factor A, chapters 
3 and 4 of the Laramie County Land Use Regulations address floodplain 
management and require specific provisions and permits for construction 
within floodplains (Laramie County 2011, pp. 165-185), which encompass 
all Colorado butterfly plant habitat within the county; therefore, 
these regulations extend some level of protection to the species and 
its habitat. While protecting riparian and wetland species is not the 
intent of these regulations, plants growing within the floodplain 
receive the habitat protections outlined as part of the floodplain 
construction avoidance provisions.
    Lands without specific regulatory mechanisms contain most 
populations of the Colorado butterfly plant. Over a decade of 
monitoring 11 occurrences on private lands in Wyoming (populations 
under WEAs) representing six 12-digit HUCs has documented fluctuations 
in population size about a stable mean, apparently driven by changes in 
precipitation and disturbance regime (USFWS 2012, pp. 11-22; USFWS 
2016b, entire). Management of lands under WEAs is discussed under 
Conservation Efforts, above.
    While no known populations occur on lands managed by BLM in 
Wyoming, BLM completed a programmatic consultation under section 7 of 
the Act on potential impacts to the species and its critical habitat 
(BLM 2005, entire). The conservation measures that BLM committed to 
under this consultation will ensure the species is not adversely 
affected should a population be discovered on BLM lands. This 
consultation included specific conservation measures to be implemented 
in grazing areas managed by BLM that overlap potential Colorado 
butterfly plant habitats. These conservation measures are incorporated 
into BLM's resource management plan, which regulates and guides how BLM 
lands are managed. Therefore, if any populations of the Colorado 
butterfly plant are found on lands administered by BLM, they would 
benefit from the conservation measures already agreed upon with the 
Service. Upon delisting (see DATES, above), when the protections of the 
Act are removed from the Colorado butterfly plant, the species will 
continue to be afforded the protections outlined in BLM's resource 
management plan until the plan is revised.
    Water use is managed under the PRRIP, as described above under 
Factor A, which ensures that water use in the Platte River is conducted 
in a way to maintain volume at certain times of the year in the central 
and lower reaches of the Platte River in Nebraska. Because all of the 
watersheds in which the Colorado butterfly plant is found occur within 
the PRRIP, the water on which the species depends is managed under this 
program (PRRIP 2019). The water that this species requires continues to 
be addressed under the PRRIP, even when the Colorado butterfly plant is 
removed from the List.
Summary of Factor D
    At the time of listing (65 FR 62302; October 18, 2000), we stated 
that no Federal or State laws or regulations specifically protected 
populations of the Colorado butterfly plant or its habitat. However, 
two of the three largest populations occur on Warren AFB and lands 
owned and managed for the species by CFCNAD where regulatory mechanisms 
now exist. Additionally, 13 years of annual monitoring of 11 survey 
areas on private lands under WEAs that has occurred since the species 
was listed has shown that land used for agricultural purposes can be 
compatible with the resilience of the species, even without any 
regulatory mechanism in place (see discussions under Factors A, C, and 
E). Consequently, we find that several conservation measures, along 
with existing regulatory mechanisms, as discussed above, will continue 
to address stressors to the Colorado butterfly plant absent protections 
under the Act.

E. Other Natural or Manmade Factors Affecting Its Continued Existence

    Factor E requires the Service to consider any other factors that 
may be affecting the Colorado butterfly plant. Under this factor, we 
discuss small population size and restricted range, herbicide spraying, 
and climate change.
Small Population Size and Restricted Range
    The final listing rule (65 FR 62302; October 18, 2000) included the 
limited range and the small population size of many populations as a 
threat to the Colorado butterfly plant. Historically, Colorado 
butterfly plant populations occurred from Castle Rock, Colorado, north 
to Chugwater, Wyoming, and east into a small portion of southwest 
Nebraska. The extent of its range was approximately 6,880 ha (17,000 
ac). Most of this range is still occupied, although some small and/or 
peripheral populations in Nebraska and Colorado have been extirpated 
since intensive survey efforts began. Despite the loss of these 
populations, the species continues to maintain multiple resilient, 
representative, and redundant

[[Page 59582]]

populations throughout nearly all of its range known at the time of 
listing (see figure, above).
    We have evidence that populations throughout the range have 
persisted despite stochastic events that may have caused short-term 
declines in number of individuals. For example, a 100-year flood in 
August 1985 along Crow Creek on the Warren AFB inundated the Crow Creek 
portion of the population, knocking down some plants and surrounding 
vegetation, and depositing sediments (Rocky Mountain Heritage Task 
Force 1987, as cited in Heidel et al. 2016, p. 2). Instead of being 
extirpated, these populations rebounded in 1986, and continue to 
persist, as shown by annual monitoring since 1988 (summarized in Heidel 
et al. 2016, pp. 2-18). Additionally, based on annual monitoring of 
populations on private property in Wyoming, stochastic events such as 
floods and hail storms have reduced population numbers during the event 
year, then populations rebounded in following years (USFWS 2012, pp. 
11-22; USFWS 2016b, entire). Individual plants may be vulnerable to 
random events such as fires, insect or disease outbreaks, or other 
unpredictable events. However, this species is adapted to disturbance, 
and rather than being extirpated, the seedbank can provide opportunity 
for populations to rebound after such events.
    The historical range included populations farther south into 
Larimer and Weld Counties in Colorado that were lost prior to the 
listing of the species in 2000. No populations in Larimer and Weld 
Counties in Colorado have been extirpated since the species was listed, 
and we do not think that further range restriction has occurred in this 
portion of the species' range. In the future, range restriction may 
occur through loss of peripheral populations in the three 12-digit HUCs 
in Nebraska where dewatering has removed formerly suitable habitat 
(Wooten 2008, entire). However, these 12-digit HUCs are downstream of 
highly viable populations in Wyoming, and do not constitute a removal 
of the species from this drainage entirely. The resiliency and 
redundancy of populations across much of the species' range indicate 
that further range restriction is not likely.
Herbicide Spraying
    At the time of listing (65 FR 62302; October 18, 2000), the non-
selective use of broadleaf herbicides to control Canada thistle, leafy 
spurge, and other nonnative, invasive plants was considered a threat to 
the Colorado butterfly plant. Non-selective spraying has had negative 
effects on some Colorado butterfly plant populations (Fertig 2000a, p. 
16). For example, in 1983, which was prior to listing, nearly one-half 
of the mapped population on Warren AFB was inadvertently destroyed when 
sprayed with Tordon[supreg], a persistent herbicide (Miller 1987, as 
cited in 65 FR 62302, October 18, 2000, p. 62307). The status of that 
portion of the population is unknown due to a subsequent lack of clear 
recordkeeping at that time, prior to a Service biologist being employed 
on site; all plant locations have been tracked in the time since the 
Service biologist and Wyoming Natural Diversity Database began working 
at Warren AFB. Herbicide use along road crossings in and adjacent to 
plant populations was also noted (65 FR 62302, October 18, 2000, p. 
62307).
    After the 2000 listing of the Colorado butterfly plant, the Service 
worked with Warren AFB and private landowners under WEAs to develop 
best management practices for applying herbicides within the vicinity 
of known occurrences to remove nonnative, invasive species while 
minimizing adverse effects to individual Colorado butterfly plants. For 
example, the WEAs require an herbicide-application buffer of 30.5 m 
(100 ft) from known locations of the Colorado butterfly plant. However, 
at one property, the landowner inadvertently sprayed individual plants 
in spring 2016. During subsequent monitoring, Service staff observed 
reddened plants with shriveled leaves, which likely reduced the vigor 
of those individuals (USFWS 2016b, entire). We presume that there will 
be no long-term effects on the population, and in fact, we found 
vigorous Colorado butterfly plants growing in this area during surveys 
in 2017. Furthermore, we anticipate that landowners will continue to 
maintain this buffer in accordance with requirements under the WEAs 
when the species is delisted, although we have no assurances that the 
buffer will be maintained post-delisting.
    While herbicide application may continue to occasionally 
inadvertently remove sprayed individuals from populations in which 
herbicide is applied, we know that unsprayed individuals persist in the 
population and can repopulate Colorado butterfly plants in areas where 
plants were killed. The seedbank can play an additional role in 
restoring Colorado butterfly plants to areas that have been sprayed. 
Based on our records, herbicide application is a management tool used 
in conjunction with nonnative, invasive species removal in only four of 
the known occurrences of the species, and these are among our largest 
and most resilient populations of the species. Our records indicate 
that, in general, application of buffers has been successful at 
reducing the presence of invasive species and competition near the 
Colorado butterfly plant (USFWS 2012, pp. 24-25; USFWS 2016b, entire), 
and when conducted appropriately, herbicide application can help 
improve habitat for the Colorado butterfly plant by eliminating 
competition.
Climate Change
    Impacts from climate change were not considered in the final rule 
to list the species (65 FR 62302; October 18, 2000) or in the critical 
habitat designation (70 FR 1940; January 11, 2005). Our current 
analyses under the Act include consideration of ongoing and projected 
changes in climate. The terms ``climate'' and ``climate change'' are 
defined by the Intergovernmental Panel on Climate Change (IPCC). The 
term ``climate change'' thus refers to a change in the mean or 
variability of one or more measures of climate (e.g., temperature or 
precipitation) that persists for an extended period, typically decades 
or longer, whether the change is due to natural variability, human 
activity, or both (IPCC 2007, p. 78). Various types of changes in 
climate can have direct or indirect effects on species. These effects 
may be positive, neutral, or negative, and they may change over time, 
depending on the species and other relevant considerations, such as the 
effects of interactions of climate with other variables (e.g., habitat 
fragmentation) (IPCC 2007, pp. 8-14, 18-19). In our analyses, we use 
our expert judgment to weigh relevant information, including 
uncertainty, in our consideration of various aspects of climate change.
    According to IPCC, ``most plant species cannot naturally shift 
their geographical ranges sufficiently fast to keep up with current and 
high projected rates of climate change on most landscapes'' (IPCC 2014, 
p. 13). Plant species with restricted ranges may experience population 
declines as a result of climate change. The concept of changing climate 
can be meaningfully assessed both by looking into the future and 
reviewing past changes. A review of Wyoming climate since 1895 
indicates that there has been a significant increase in the frequency 
of warmer-than-normal years, an increase in temperatures throughout all 
regions of the State, and a decline in the frequency of ``wet'' winters 
(Shumann 2011, entire). Data from the Cheyenne area over the past 30 
years indicate a rise in spring

[[Page 59583]]

temperatures (Heidel et al. 2016, pp. 6-7). The current climate in 
Colorado butterfly plant habitat is quite variable, with annual 
precipitation ranging from 25-50 cm (10-20 in) of rain and 81-275 cm 
(32-108 in) of snow per year near the center of the species' range at 
Cheyenne Municipal Airport (NOAA 2016, entire). The years 2000 through 
2006 appeared to have lower than average precipitation (NOAA 2016, 
entire), which may have affected the ability of plants to withstand a 
flea beetle outbreak in 2007 (Heidel et al. 2011, p. 286). The Colorado 
butterfly plant is semelparous (individual plants are first vegetative, 
then flower and fruit, and then die). Therefore, individuals are likely 
capable of remaining in a vegetative state under some conditions and 
duration until suitable flowering conditions exist, suggesting that the 
species is adapted to variability in the amount and timing of 
precipitation.
    Climate change may affect the timing and amount of precipitation as 
well as other factors linked to habitat conditions for the Colorado 
butterfly plant. For example, ensemble climate models predict that by 
2050, watersheds containing the species will become warmer for all four 
seasons, and precipitation will increase in the winter and remain about 
the same in spring, summer, and fall (USGS 2016, pp. 1-3). Snow water 
equivalent will decrease in winter and spring, and soil water storage 
will decrease in all four seasons (USGS 2016, pp. 4-5). This climate 
modeling predicts an increase in winter precipitation, but decreases in 
soil water storage will mean less water for subirrigation of the 
species' habitat. This may mean a shorter window for seed germination, 
lower seed production, and potentially increased years at the rosette 
stage to obtain sufficient resources to bolt and flower. However, we 
also understand that C3 plants (plants which combine water, 
sugar, and carbon dioxide in carbon fixation), including this species, 
have a 41 percent proportional increase in growth resulting from a 100 
percent increase in carbon dioxide (Poorter 1993, p. 77). This increase 
in growth rate due to higher carbon dioxide may counteract the need to 
spend more time in the vegetative portion of the life cycle in response 
to climate change. Furthermore, exposure to higher concentrations of 
carbon dioxide causes plants to reduce the number and aperture of their 
stomata, which decreases the amount of water that is lost during 
transpiration (Lammertsma et al. 2011, p. 4035), which may offset 
declines in water availability during droughts. Additionally, 
populations are able to withstand several consecutive years of poor 
growing conditions and still rebound with suitable conditions (USFWS 
2012, pp. 11-22; USFWS 2016b, entire). The effects of climate change 
have the potential to affect the species and its habitat if flea beetle 
outbreaks occur or if flowering levels are suppressed. Although we lack 
scientific certainty regarding what those changes may ultimately mean 
for the species, based on the best available information, we expect 
that the species' current adaptations to cope with climate variability 
will mitigate any impact on population persistence.
Summary of Factor E
    Under this factor, we discussed the Colorado butterfly plant's 
small population size and restricted range, herbicide spraying, and 
climate change.
    In 2000, when we listed the species, the stochastic extirpation of 
individual populations suggested that the range of the species might be 
declining. Despite the fact that some populations in Colorado, Wyoming, 
and Nebraska were extirpated prior to listing, and others in Nebraska 
were extirpated after listing, four additional populations have been 
discovered, two of which are protected, and there are still 
representative and redundant populations occurring throughout the range 
of the species. Further, individuals and populations are resilient to a 
single herbicide application, and have been shown to survive or bounce 
back from such events. Information shared with landowners has greatly 
reduced the indiscriminate application of herbicides near populations 
of the Colorado butterfly plant. Finally, while the effects of climate 
change present a largely unknown potential stressor to the species, 
individual plants are capable of deferring the reproductive stage until 
suitable conditions are available, populations are made up of 
individuals found in a range of microhabitats, and populations are 
located within various ecological settings within the species' range. 
This indicates that the resiliency, redundancy, and representation of 
populations will maintain the species in the face of climate change.

Combination of Factors

    Many of the stressors discussed in this analysis could work in 
concert with each other and result in a cumulative adverse effect to 
the Colorado butterfly plant, e.g., one stressor may make the species 
more vulnerable to other threats. For example, stressors discussed 
under Factor A that individually do not rise to the level of a threat 
could together result in habitat loss. Similarly, small population size 
and a restricted range in combination with stressors discussed under 
Factor A could present a potential concern. However, most of the 
potential stressors we identified either have not occurred to the 
extent originally anticipated at the time of listing or are adequately 
managed as described in this rule. Furthermore, those stressors that 
are evident, such as the effects of climate change and grazing, appear 
well-tolerated by the species. In addition, for the reasons discussed 
in this rule, we do not anticipate stressors to increase on lands that 
afford protections to the species (Warren AFB and CFCNAD lands) where 
many of the largest populations occur. Furthermore, the increases 
documented in the number and size of many populations since the species 
was listed do not indicate that cumulative effects of various 
activities and stressors are affecting the viability of the species at 
this time or into the future.

Summary of Comments and Recommendations

    In the proposed rule published in the Federal Register on June 8, 
2018 (83 FR 26623), we requested that all interested parties submit 
written comments on our proposal to delist the Colorado butterfly plant 
by August 7, 2018. We also contacted appropriate Federal and State 
agencies, scientific experts and organizations, and other interested 
parties and invited them to comment on the proposal. We did not receive 
any requests for a public hearing. All substantive information provided 
during the comment period has either been incorporated directly into 
this final rule or is addressed below.

Peer Reviewer Comments

    In accordance with our peer review policy published on July 1, 1994 
(59 FR 34270) and updated guidance issued on August 22, 2016 (USFWS 
2016c, entire), we solicited expert opinion from three knowledgeable 
individuals with scientific expertise that included familiarity with 
the Colorado butterfly plant, its habitat, its biological needs and 
potential threats, or principles of conservation biology. We received a 
response from one peer reviewer.
    We reviewed all comments we received from the peer reviewer for 
substantive issues and new information regarding the proposed delisting 
of the Colorado butterfly plant. The peer reviewer provided additional 
information, clarifications, and suggestions to improve the final rule, 
which we include in this rule or address

[[Page 59584]]

in the responses to comments below. The peer reviewer did not favor or 
oppose delisting the Colorado butterfly plant and provided only 
technical comments and editorial suggestions on the rule.
    (1) Comment: The peer reviewer brought up the concern of genetic 
contamination resulting from unauthorized introductions of plant 
material from unknown or known sources as a potential threat to the 
species. The peer reviewer provided no data on genetic contamination on 
this or any related species to support this concern.
    Our Response: The Service has no information that suggests that 
genetic contamination is occurring or has occurred or that unauthorized 
introductions have had a negative effect on any known populations. 
Therefore, we do not discuss genetic contamination as a potential 
threat affecting the species in this rule.
    (2) Comment: The peer reviewer suggested that we clarify the 
definition of a population used in the final rule because the term 
``watershed'' can be unclear.
    Our Response: Throughout this rule, we refer to a population of the 
Colorado butterfly plant as all plants that occur within the same 12-
digit hydrologic unit code (HUC) watershed. Plants in the same drainage 
but upstream or downstream of the 12-digit HUC are considered separate 
populations.
    (3) Comment: The peer reviewer questioned our description of 
resiliency, asking why we did not consider any population to be stable 
that persists year after year.
    Our Response: The analysis for the delisting of the Colorado 
butterfly plant focuses on the resiliency of populations rather than 
focusing on the term ``stable'' because of the dramatic variation in 
population numbers exhibited by most monitored populations. Resiliency 
includes not only population numbers but also trends in population 
numbers in response to management and stressors. A hypothetical 
population may persist year after year during the monitoring, but with 
declining numbers in response to management activities. We would not 
consider such a population to have high resiliency due to the declining 
trend and management that is not compatible with the persistence of the 
population.
    (4) Comment: The peer reviewer asked if suitable habitat is still 
present at the six historical occurrences not documented since 1984, 
and when the sites were last surveyed in a good year.
    Our Response: The Service has not made observations of habitat 
quality outside of populations under agreement. Element occurrence 
records from State agencies indicate visits to the sites in the 2000s 
and 2010s without finding Colorado butterfly plants, and included 
descriptions of habitat quality being typically suitable for the 
Colorado butterfly plant.
    (5) Comment: The peer reviewer pointed out that our analysis of 
population resiliency did not include acreage of suitable habitat 
across years.
    Our Response: The 2000 listing rule states, ``In order for a 
population to sustain itself, there must be enough reproducing 
individuals and sufficient habitat to ensure survival of the 
population. It is not known if the scattered populations of [the 
Colorado butterfly plant] contain sufficient individuals and diversity 
to ensure their continued existence over the long term'' (65 FR 62302, 
October 18, 2000, p. 62308). The Service has focused on the number of 
individuals and the diversity of their habitats in our monitoring 
efforts, specifically because the acreage of suitable habitat has been: 
(a) Difficult to determine based on the wide variation in habitat types 
occupied by this species; (b) occupied or unoccupied in any given year; 
(c) variable due to the frequent disturbances (floods, mowing, 
succession, etc.) affecting areas typically occupied by the Colorado 
butterfly plant; and/or (d) more or less constant in the agreement 
areas and does not provide us with valuable information about how the 
population is faring.
    (6) Comment: The peer reviewer requested that a table be included 
in the final rule describing each of the occurrences/populations by 
name and State, the acres of suitable habitat present at each site, 
ownership of the site, the mean number of individuals, and indication 
of the threats to each occurrence at listing compared to now.
    Our Response: Due to complexity of the table and costs associated 
with publication in the Federal Register, in this rule we omit the 
requested table, which can be found in the 2017 species biological 
report at https://www.regulations.gov under the supporting materials for 
Docket No. FWS-R6-ES-2018-0008. We have attempted to crosswalk all 
references to specific populations in this rule with other population 
identifiers used in the 2000 listing rule (65 FR 62302; October 18, 
2000) and the 2005 designation of critical habitat (70 FR 1940; January 
11, 2005).
    (7) Comment: The peer reviewer pointed out an inconsistency in the 
description of management methods used by the City of Fort Collins 
Natural Areas Department at the Meadow Springs Ranch. The 2000 listing 
rule (65 FR 62302; October 18, 2000) said that the Meadow Springs Ranch 
was managed for municipal sewage treatment while the 2018 delisting 
proposed rule (83 FR 26623; June 8, 2018) described the site as managed 
to maintain suitable habitat for the Colorado butterfly plant.
    Our Response: This large ranch is managed for both purposes, 
although the portion of the ranch where the Colorado butterfly plant 
occurs is not used for municipal sewage.
    (8) Comment: The peer reviewer requested population-by-population 
assessment of threats and conservation actions.
    Our Response: This final rule summarizes the overall picture of 
population status and analysis of stressors. Potential threats 
affecting populations are described in detail in the 2017 species 
biological report, which is available at https://www.regulations.gov 
under the supporting materials for Docket No. FWS-R6-ES-2018-0008.
    (9) Comment: The peer reviewer questioned why the Service did not 
include potential loss of isolated populations that may contain unique 
alleles as a threat under Factor E.
    Our Response: The genetic work conducted on this species to date 
has found very low genetic variation within and among populations 
(Tuthill and Brown 2003, pp. 254-256; Floyd 1995, pp. 73-81). There is 
no information to suggest that loss of isolated populations would 
reduce the genetic variation of the species, so that is not assessed as 
a threat under Factor E in this rule.

Public Comments

    We received 14 letters from the public that provided comments on 
the proposed rule. Ten of the commenters included their views on 
whether the Colorado butterfly plant should be delisted. We also 
received four comments that were not directly related to the proposed 
action in any way and are not addressed below.
    Relevant public comments are addressed in the following summary, 
and new information was incorporated into this final rule as 
appropriate.
    (1) Comment: Three commenters acknowledged recovery of the Colorado 
butterfly plant, but suggested that we should not delist the species 
due to the loss of protections under the Act.
    Our Response: The Act has been successfully applied to this species 
through work with Federal and private landowners who manage their lands 
while protecting the species. For the reasons discussed in this rule, 
the

[[Page 59585]]

species is not in danger of extinction now or in the foreseeable 
future, and so it no longer meets the Act's definition of a threatened 
species and no longer requires the protections of the Act.
    (2) Comment: One commenter said that climate change was not 
addressed adequately in the proposed rule.
    Our Response: The potential effects of climate change on the 
viability of this species are discussed in more detail in this final 
rule. In particular, we note that plants may fare better with increased 
carbon dioxide (CO2) due to the increased ability to 
photosynthesize, paired with decreased water loss through transpiration 
because plants have reduced number and aperture of stomata under 
heightened CO2. Predictions of temperature and precipitation 
regimes are unclear, as are the predictions regarding severity of 
storms, although we understand that this species is adapted to respond 
to unfavorable conditions by delaying bolting. This may be offset by 
the heightened ability for rapid growth due to increased 
CO2.
    (3) Comment: One commenter supported delisting the species but 
argued to maintain designated critical habitat.
    Our Response: Under the Act, only those species listed as 
endangered or threatened species can have designated critical habitat. 
Therefore, the delisting of the Colorado butterfly plant also removes 
the designation of the plant's critical habitat.
    (4) Comment: One commenter was concerned that threats had not been 
adequately addressed and that the species would need to be relisted in 
the future.
    Our Response: None of the stressors that were thought to affect 
this species in 2000, when we listed the species (65 FR 62302; October 
18, 2000), is currently affecting this species at a high level and is 
not predicted to worsen, as discussed in the 2017 species biological 
report, which is available at https://www.regulations.gov under the 
supporting materials for Docket No. FWS-R6-ES-2018-0008. The Service is 
implementing a post-delisting monitoring plan that will allow for the 
monitoring of a subset of populations throughout the range of the 
species. If monitored populations are determined to be imperiled, the 
Service has a process for re-evaluating the status of the species and 
reinstating protections under the Act, if needed.

Determination of Species 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 ``endangered species'' or 
``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 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. We must consider these same five 
factors in delisting a species. We may delist a species according to 50 
CFR 424.11(d) if the best available scientific and commercial data 
indicate that the species is neither endangered nor threatened for the 
following reasons: (1) The species is extinct; (2) the species has 
recovered and is no longer endangered or threatened; and/or (3) the 
original scientific data used at the time the species was classified 
were in error. The same factors apply whether we are analyzing the 
species' status throughout all of its range or a significant portion of 
its range.

Colorado Butterfly Plant's Status Throughout All of Its Range

    After evaluating threats to the species under the section 4(a)(1) 
factors, we considered all of the stressors identified at the time of 
listing in 2000, as well as newly identified potential stressors such 
as oil and gas energy development and the effects of climate change. 
The stressors considered in our five-factor analysis (discussed in 
detail above under Summary of Factors Affecting the Species) fall into 
one or more of the following categories:
     Minimized or mitigated: The following stressors are 
adequately managed, and existing information indicates that this will 
not change in the future: Residential, urban, and energy development; 
agricultural practices; water management; overutilization; and 
herbicide spraying.
     Avoided: The following stressor has not occurred to the 
extent anticipated at the time of listing, and existing information 
indicates that this will not change in the future: Small population 
size and restricted range.
     Tolerated: The species is tolerant of the following 
stressors, and existing information indicates that this will not change 
in the future: Natural succession and competition with nonnative, 
invasive species; disease and predation; and the effects of climate 
change.
    These conclusions are supported by the available information 
regarding the species' abundance, distribution, and trends as outlined 
in the species biological report (USFWS 2017, entire), and are in 
agreement with conclusions presented in our 2010 recovery outline 
(USFWS 2010, entire) and in our 5-year review (USFWS 2012, entire) that 
the Colorado butterfly plant is not facing any imminent or significant 
threats. Thus, after assessing the best available information, we 
conclude that the Colorado butterfly plant is not in danger of 
extinction throughout all of its range nor is it likely to become so in 
the foreseeable future.

Colorado Butterfly Plant's 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 (SPR). Where the best available information allows the 
Service to determine a status for the species rangewide, that 
determination should be given conclusive weight because a rangewide 
determination of status more accurately reflects the species' degree of 
imperilment and better promotes the purposes of the Act. Under this 
reading, we should first consider whether the species warrants listing 
``throughout all'' of its range and proceed to conduct a ``significant 
portion of its range'' analysis if, and only if, a species does not 
qualify for listing as either an endangered or a threatened species 
according to the ``throughout all'' language.
    Having determined that the Colorado butterfly plant is not in 
danger of extinction or likely to become so in the foreseeable future 
throughout all of its range, we now consider whether it may be in 
danger of extinction or likely to become so in the foreseeable future 
in an SPR. The range of a species can theoretically be divided into 
portions in an infinite number of ways, so we first screen the 
potential portions of the species' range to determine if there are any 
portions that warrant further consideration. To do the ``screening'' 
analysis, we ask whether there are portions of the species' range for 
which there is substantial information indicating that: (1) The portion 
may be

[[Page 59586]]

significant; and (2) the species may be, in that portion, either in 
danger of extinction or likely to become so in the foreseeable future. 
For a particular portion, if we cannot answer both questions in the 
affirmative, then that portion does not warrant further consideration 
and the species does not warrant listing because of its status in that 
portion of its range. Conversely, we emphasize that answering these 
questions in the affirmative is not a determination that the species is 
in danger of extinction or likely to become so in the foreseeable 
future throughout a significant portion of its range--rather, it is a 
step in determining whether a more detailed analysis of the issue is 
required.
    If we answer these questions in the affirmative, we then conduct a 
more thorough analysis to determine whether the portion does indeed 
meet both of the SPR prongs: (1) The portion is significant; and (2) 
the species is, in that portion, either in danger of extinction or 
likely to become so in the foreseeable future. Confirmation that a 
portion does indeed meet one of these prongs does not create a 
presumption, prejudgment, or other determination as to whether the 
species is an endangered species or threatened species. Rather, we must 
then undertake a more detailed analysis of the other prong to make that 
determination. Only if the portion does indeed meet both SPR prongs 
would the species warrant listing because of its status in a 
significant portion of its range.
    At both stages in this process--the stage of screening potential 
portions to identify any portions that warrant further consideration 
and the stage of undertaking the more detailed analysis of any portions 
that do warrant further consideration--it might be more efficient for 
us to address the ``significance'' question or the ``status'' question 
first. Our selection of which question to address first for a 
particular portion depends on the biology of the species, its range, 
and the threats it faces. Regardless of which question we address 
first, if we reach a negative answer with respect to the first question 
that we address, we do not need to evaluate the second question for 
that portion of the species' range.
    For the Colorado butterfly plant, we chose to evaluate the status 
question (i.e., identifying portions where the Colorado butterfly plant 
may be in danger of extinction or likely to become so in the 
foreseeable future) first. To conduct this screening, we considered 
whether the threats are geographically concentrated in any portion of 
the species' range at a biologically meaningful scale. We examined the 
following threats, including cumulative effects: Residential, urban, 
and energy development; agricultural practices; water management; 
natural succession and competition with nonnative, invasive species; 
overutilization; disease and predation; inadequacy of existing 
regulatory mechanisms; small population size and restricted range; 
herbicide spraying; and the effects of climate change. The only 
geographically concentrated threat is grazing and water management of 
the three 12-digit HUCs in Nebraska. Grazing and water management, 
particularly the dewatering of Lodgepole Creek downstream of the 
Wyoming/Nebraska border in the three 12-digit HUCs in Nebraska, has 
proven to impact populations in that portion of the species' range. 
This stressor has affected these populations to a level that the 
populations were presumed extirpated at the time we designated critical 
habitat for this species (70 FR 1940; January 11, 2005). However, after 
water was reintroduced to the creek by a landowner, Colorado butterfly 
plants were again observed in Lodgepole Creek (Wooten 2008, p. 4). It 
is possible that the species only occurs in this portion of its range 
during times of adequate subirrigation and surface flows, and that 
seeds either remain dormant at this location for several years or are 
transported from neighboring populations located upstream on Lodgepole 
Creek in Wyoming. Nevertheless, the removal of water from Lodgepole 
Creek impacts populations of the Colorado butterfly plant within this 
portion of the species' range.
    Because we identified an area on the periphery of the species' 
current range as warranting further consideration due to the geographic 
concentration of threats from water management, we then evaluated 
whether this area may be significant to the Colorado butterfly plant. 
The Service's most-recent definition of ``significant'' has been 
invalidated by the courts (for example, Desert Survivors v. Dep't of 
the Interior, No. 16-cv-01165-JCS (N.D. Cal. Aug. 24, 2018)). 
Therefore, we determined whether the three populations in Nebraska 
could be significant under any reasonable definition of 
``significant.'' To do this, we evaluated whether these populations 
taken together may be biologically important in terms of the 
resiliency, redundancy, or representation of the species.
    Regarding redundancy, the populations within this portion of the 
range occur on the eastern extreme of the historical range of the 
species and represent a very small component of the total distribution 
of the species, occurring downstream of several highly viable 
populations. Therefore, these populations do not substantially increase 
redundancy at the species level. Regarding resiliency, individual 
plants in this portion of the range may be resilient to dewatering or 
other stressors, but the populations contain few individuals and are, 
therefore, threatened by stochastic events. Regarding representation, 
we understand that there may be connectivity among the populations 
occurring in Nebraska and the populations upstream on Lodgepole Creek 
in Wyoming. However, this connectivity is likely only through limited 
pollinator movement among the few flowering plants at any location, and 
through seed dispersal downstream from Wyoming to Nebraska, considering 
the distance is too great (greater than 1 km (0.6 mi)) for most 
pollinators to travel (Heidel 2016, pers. comm.). Consequently, the 
populations in Nebraska are likely not contributing any genetic 
information upstream. We do not have genetic information on these 
populations, but we understand that the populations in this portion of 
the species' range do not occupy unique ecological settings, have 
unique morphology, or have differing phenology than other populations 
of the species on Lodgepole Creek or in the rest of the species' range.
    After careful examination of the Colorado butterfly plant 
population in the context of our definition of ``significant portion of 
its range,'' we determined that the area in Nebraska on the periphery 
of the range warranted further consideration because threats are 
geographically concentrated there. After identifying this area, we 
determined that it is not biologically significant to the Colorado 
butterfly species as a whole because the Colorado butterfly plants in 
this area do not contribute meaningfully to the overall viability of 
the species. This is because the remainder of the species is 
characterized by high levels of resiliency, redundancy, and 
representation; the remainder of the species contains all of the highly 
and moderately resilient populations (high resiliency), is comprised of 
more than 20 populations distributed through a geographically connected 
area (high redundancy), and includes all of the ecological settings 
this species is known to inhabit (high representation). Therefore, we 
have determined that the Colorado butterfly plant is not in danger of 
extinction, or likely to become so in the foreseeable future, within a

[[Page 59587]]

significant portion its the range. Our approach to analyzing SPR in 
this determination is consistent with the court's holding in Desert 
Survivors v. Department of the Interior, No. 16-cv-01165-JCS, 2018 WL 
4053447 (N.D. Cal. Aug. 24, 2018).

Colorado Butterfly Plant's Determination of Status

    Our review of the best available scientific and commercial 
information indicates that the Colorado butterfly plant is not in 
danger of extinction or likely to become an endangered species within 
the foreseeable future throughout all or a significant portion of its 
range. Therefore, we are removing the Colorado butterfly plant from the 
Federal List of Endangered and Threatened Plants at 50 CFR 17.12(h) due 
to recovery.

Effects of the Rule

    This final rule revises 50 CFR 17.12(h) by removing the Colorado 
butterfly plant from the Federal List of Endangered and Threatened 
Plants. On the effective date of this rule (see DATES, above), the 
prohibitions and conservation measures provided by the Act, 
particularly through sections 7 and 9, no longer apply to this species. 
Federal agencies will no longer be required to consult with the Service 
under section 7 of the Act in the event that activities they authorize, 
fund, or carry out may affect the Colorado butterfly plant or its 
designated critical habitat. This rule also removes the designation of 
critical habitat for the Colorado butterfly plant in Wyoming (codified 
at 50 CFR 17.96(a)).

Post-Delisting Monitoring

    Section 4(g)(1) of the Act requires us, in cooperation with the 
States, to implement a monitoring program for not less than 5 years for 
all species that have been delisted due to recovery. The purpose of 
this requirement is to develop a program that detects the failure of 
any delisted species to sustain itself without the protective measures 
provided by the Act. If, at any time during the monitoring period, data 
indicate that protective status under the Act should be reinstated, we 
can initiate listing procedures, including, if appropriate, emergency 
listing.
    We are delisting the Colorado butterfly plant based on recovery 
actions taken and new information we have received. As delisting is due 
in part to recovery actions taken by Warren AFB, CFCNAD, and BLM, we 
have prepared a final post-delisting monitoring (PDM) plan for the 
Colorado butterfly plant with input from these and other partners. 
Monitoring will occur annually for at least 5 years, beginning in 2020. 
At the end of 5 years, the species' population status will be 
evaluated, with four possible outcomes: (1) The Colorado butterfly 
plant remains secure without the Act's protections, resulting in the 
conclusion of the post-delisting monitoring; (2) the Colorado butterfly 
plant species may be less secure than anticipated at the time of 
delisting, but information does not indicate that the species meets the 
definition of an endangered species or a threatened species, resulting 
in an extension of the PDM plan for an additional 3 to 5 years; (3) the 
PDM yields substantial information indicating that stressors may be 
causing a decline in the status of Colorado butterfly plant since the 
time of delisting, resulting in the initiation of a formal status 
review to determine whether relisting the species is appropriate; or 
(4) the PDM documents a decline in the species' probability of 
persistence, such that the species once again meets the definition of 
an endangered species or a threatened species under the Act, resulting 
in the immediate initiation of relisting the species.
    A final PDM plan is available (see ADDRESSES or https://www.regulations.gov under Docket No. FWS-R6-ES-2018-0008). We will work 
closely with our partners to maintain the recovered status of the 
Colorado butterfly plant and ensure post-delisting monitoring is 
conducted and future management strategies are implemented (as 
necessary) to benefit the Colorado butterfly plant.

Required Determinations

National Environmental Policy Act

    We have determined that environmental assessments and environmental 
impact statements, as defined under the authority of the National 
Environmental Policy Act of 1969 (42 U.S.C. 4321 et seq.), need not be 
prepared in connection with regulations 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).

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), E.O. 13175, 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 Tribes will 
be affected by this rule because no Tribal lands, sacred sites, or 
resources will be affected by the removal of the Colorado butterfly 
plant from the List of Endangered and Threatened Plants.

References Cited

    A complete list of all references cited in this rule is 
available at https://www.regulations.gov at Docket No. FWS-R6-ES-
2018-0008, or upon request from the Wyoming Ecological Services 
Field Office (see FOR FURTHER INFORMATION CONTACT).

Authors

    The primary authors of this final rule are staff members of the 
Wyoming Ecological Services Field Office.

List of Subjects in 50 CFR Part 17

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

Regulation Promulgation

    Accordingly, we 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.


Sec.  17.12  [Amended]

0
2. Amend Sec.  17.12(h) by removing the entry ``Gaura neomexicana ssp. 
coloradensis'' under FLOWERING PLANTS from the List of Endangered and 
Threatened Plants.


Sec.  17.96  [Amended]

0
3. Amend Sec.  17.96(a) by removing the entry ``Family Onagraceae: 
Gaura neomexicana ssp. coloradensis (Colorado butterfly plant)''.


[[Page 59588]]


    Dated: October 29, 2019.
Margaret E. Everson,
Principal Deputy Director, U.S. Fish and Wildlife Service, Exercising 
the Authority of the Director, For the U.S. Fish and Wildlife Service.
[FR Doc. 2019-24124 Filed 11-4-19; 8:45 am]
 BILLING CODE 4333-15-P