Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for Nine Bexar County, Texas, Invertebrates, 9872-9937 [2011-3038]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 76, Number 35 (Tuesday, February 22, 2011)]
[Proposed Rules]
[Pages 9872-9937]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-3038]



[[Page 9871]]

Vol. 76

Tuesday,

No. 35

February 22, 2011

Part II





Department of the Interior





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Fish and Wildlife Service



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50 CFR Part 17



Endangered and Threatened Wildlife and Plants; Designation of Critical 
Habitat for Nine Bexar County, Texas, Invertebrates; Proposed Rule

Federal Register / Vol. 76 , No. 35 / Tuesday, February 22, 2011 / 
Proposed Rules

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R2-ES-2010-0091; MO 92210-0-009]
RIN 1018-AX11


Endangered and Threatened Wildlife and Plants; Designation of 
Critical Habitat for Nine Bexar County, Texas, Invertebrates

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to 
revise critical habitat designation for the Rhadine exilis (ground 
beetle, no common name); Rhadine infernalis (ground beetle, no common 
name); Helotes mold beetle (Batrisodes venyivi); Cokendolpher Cave 
harvestman (Texella cokendolpheri); Robber Baron Cave meshweaver 
(Cicurina baronia); Madla Cave meshweaver (Cicurina madla); and Braken 
Bat Cave meshweaver (Cicurina venii) under the Endangered Species Act 
of 1973, as amended (Act). We also propose to designate critical 
habitat for the Government Canyon Bat Cave meshweaver (Cicurina 
vespera) and Government Canyon Bat Cave spider (Neoleptoneta microps). 
These species are collectively known as the nine Bexar County 
invertebrates. In total, we are proposing approximately 6,906 acres 
(ac) (2,795 hectares (ha)) as critical habitat for these invertebrates. 
The proposed critical habitat is located in Bexar County, Texas.

DATES: We will consider comments received or postmarked on or before 
April 25, 2011. We must receive requests for public hearings, in 
writing, at the address shown in the FOR FURTHER INFORMATION CONTACT 
section by April 8, 2011.

ADDRESSES: You may submit comments by one of the following methods:
     Federal eRulemaking Portal: https://www.regulations.gov. 
Follow the instructions for submitting comments on Docket No. FWS-R2-
ES-2010-0091.
     U.S. mail or hand-delivery: Public Comments Processing, 
Attn: Docket No. FWS-R2-ES-2010-0091; Division of Policy and Directives 
Management; U.S. Fish and Wildlife Service; 4401 N. Fairfax Drive, 
Suite 222; Arlington, VA 22203.
    We will not accept e-mail or faxes. We will post all comments on 
https://www.regulations.gov. This generally means that we will post any 
personal information you provide us (see the Public Comments section 
below for more information).

FOR FURTHER INFORMATION CONTACT: Adam Zerrenner, Field Supervisor, U.S. 
Fish and Wildlife Service, Austin Ecological Services Field Office, 
10711 Burnet Road, Suite 200, Austin, TX 78758; by telephone at 512-
490-0057 x248; or by facsimile at 512-490-0974. If you use a 
telecommunications device for the deaf (TDD), call the Federal 
Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION: 

Public Comments

    This document consists of: (1) A proposed rule to revise designated 
critical habitat for the Rhadine exilis (ground beetle, no common 
name); Rhadine infernalis (ground beetle, no common name); Helotes mold 
beetle (Batrisodes venyivi); Cokendolpher Cave harvestman (Texella 
cokendolpheri); Robber Baron Cave meshweaver (Cicurina baronia); Madla 
Cave meshweaver (Cicurina madla); and Braken Bat Cave meshweaver 
(Cicurina venii); and (2) A proposed rule to designate critical habitat 
for Government Canyon Bat Cave meshweaver (Cicurina vespera) and 
Government Canyon Bat Cave spider (Neoleptoneta microps).
    We intend that any final action resulting from this proposed rule 
will be based on the best scientific and commercial data available and 
be as accurate and as effective as possible. Therefore, we request 
comments or information from other concerned government agencies, the 
scientific community, industry, or other interested parties concerning 
this proposed rule. We particularly seek comments concerning:
    (1) The reasons why we should or should not designate habitat as 
``critical habitat'' under section 4 of the Endangered Species Act of 
1973, as amended (Act) (16 U.S.C. 1531 et seq.) including whether there 
are threats to the species from human activity, the degree of which can 
be expected to increase due to the designation, and whether that 
increase in threat outweighs the benefit of designation such that the 
designation of critical habitat may not be prudent.
    (2) Specific information on:
     The amount and distribution of any of the nine Bexar 
County invertebrates' habitat;
     What areas occupied at the time of listing and that 
contain features essential to the conservation of the species should be 
included in the designation and why;
     Special management considerations or protections that the 
features essential to the conservation of the nine Bexar County 
invertebrates identified in this proposal may require, including 
managing for the potential effects of climate change;
     What areas not occupied at the time of listing are 
essential for the conservation of the species and why; and
     Site-specific information on subsurface geologic barriers 
to movement of the species or lack thereof.
     The taxonomy and status of the ground beetle previously 
identified as Rhadine exilis in Black Cat Cave (proposed Unit 13) and 
the value of the cave and unit for conservation of the species.
    (3) Land use designations and current or planned activities in the 
subject areas and their possible impacts on proposed critical habitat.
    (4) Any probable economic, national security, or other relevant 
impacts of designating any area that may be included in the final 
designation. We are particularly interested in any impacts on small 
entities or families, and the benefits of including or excluding areas 
that exhibit these impacts.
    (5) Information on whether the benefit of an exclusion of any 
particular area outweighs the benefit of inclusion under section 
4(b)(2) of the Act, in particular for those management plans covering 
specified lands used as mitigation under the La Cantera Habitat 
Conservation Plan (HCP) and lands on which impacts to the species have 
been authorized under that HCP. Copies of the La Cantera HCP are 
available from the Austin Ecological Services Field Office (see FOR 
FURTHER INFORMATION CONTACT).
    (6) Information on the projected and reasonably likely impacts of 
climate change on any of the nine Bexar County invertebrates and the 
critical habitat areas we are proposing.
    (7) Information related to our 90-day finding on the July 8, 2010, 
petition to remove critical habitat Unit 13 from designation (see 
Previous Federal Actions below).
    (8) Whether we could improve or modify our approach to designating 
critical habitat in any way to provide for greater public participation 
and understanding, or to better accommodate public concerns and 
comments.
    You may submit your comments and materials concerning this proposed 
rule by one of the methods listed in the ADDRESSES section. We will not 
accept

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comments sent by e-mail or fax or to an address not listed in the 
ADDRESSES section. We will post your entire comment--including your 
personal identifying information--on https://www.regulations.gov. You 
may request at the top of your document that we withhold personal 
information such as your street address, phone number, or e-mail 
address from public review. However, we cannot guarantee that we will 
be able to do so.
    Comments and materials we receive, as well as supporting 
documentation we used in preparing this proposed rule, will be 
available for public inspection on https://www.regulations.gov, or by 
appointment, during normal business hours, at the U.S. Fish and 
Wildlife Service, Austin Ecological Services Field Office (see FOR 
FURTHER INFORMATION CONTACT).

Background

    It is our intent to discuss only those topics directly relevant to 
the designation and revised designation of critical habitat in this 
proposed rule. For more information on the Rhadine exilis (ground 
beetle, no common name), Rhadine infernalis (ground beetle, no common 
name), Helotes mold beetle, Cokendolpher Cave harvestman, Robber Baron 
Cave meshweaver, Madla Cave meshweaver, Braken Bat Cave meshweaver, 
Government Canyon Bat Cave meshweaver, and Government Canyon Bat Cave 
spider, refer to the final listing rule published in the Federal 
Register on December 26, 2000 (65 FR 81419), the proposed critical 
habitat designation published August 27, 2002 (67 FR 55063), and the 
final critical habitat designation published April 8, 2003 (68 FR 
17155).
    The nine species for which we are proposing to designate critical 
habitat or to revise critical habitat are collectively known as the 
nine Bexar County invertebrates, and they inhabit caves or other 
features known as ``karst.'' The term karst refers to a type of terrain 
that is formed by the slow dissolution of calcium carbonate from 
limestone bedrock by mildly acidic groundwater. This process creates 
numerous cave openings, cracks, fissures, fractures, and sinkholes, and 
the bedrock resembles Swiss cheese. All of these species are 
subterranean-dwelling, non-aquatic species of local distribution in 
north and northwest Bexar County, Texas. They spend their entire lives 
underground, but surface features are very important as they provide 
links to drainage into the caves. The following information relates to 
the designation for all nine species.
    Individuals comprising the nine Bexar County invertebrates are 
small, ranging in length from 0.04 inch (in) (1 millimeter (mm)) to 0.4 
in (1 centimeter (cm)). They are eyeless, or essentially eyeless, and 
most lack pigment or coloration. Adaptations to cave life may include 
adjustments to the low quantities of food, including low metabolism; 
long legs for efficient movement; and loss of eyes, possibly as an 
energy-saving trade-off (Howarth 1983, pp. 374-376). These 
invertebrates may be able to survive from months to years existing on 
little or no food (Howarth 1983, p. 375). Average life spans of the 
listed Bexar County invertebrates in central Texas are unknown, but are 
likely multiple years for some species (Cicurina spp.), based on 
observations of juveniles kept in captivity (Veni and Associates 1999, 
p. 165). Reproductive rates of troglobites (small, cave-dwelling 
animals that have adapted to their dark surroundings), such as these 
nine invertebrates, are typically very low (Poulson and White 1969, p. 
977; Howarth 1983, p. 375).
    Based on surveys conducted by Krejca and Weckerly (2007, pp. 286-
288), Culver (1986, p. 429), Elliott (1994a, p. 15), and Hopper (2000, 
p. 459), population sizes of troglobitic invertebrates in humanly-
accessible karst features are typically low, with most species known 
from only a few specimens (Culver et al. 2000, p. 2350). While very 
little is known about the ecology of the nine Bexar County 
invertebrates, they are known to be top predators in their ecosystem 
(Service 2008, p. 1.4-5) and are dependent on the stability of their 
prey base that make up the lower trophic levels of the karst ecosystem 
(Taylor et al. 2004, p. 28).
    Because sunlight is absent or only present in extremely low levels 
in caves, most karst ecosystems depend on nutrients derived from the 
surface (organic material brought in by animals, washed in, or 
deposited through root masses), or imported through the feces, eggs, 
and carcasses of trogloxenes (species that regularly inhabit caves for 
refuge, but return to the surface to feed) and troglophiles (species 
that may complete their life cycle in the cave, but may also be found 
on the surface) (Barr 1968, pp. 47-48; Poulson and White 1969, pp. 971-
972; Howarth 1983, pp. 376-377; Culver 1986, p. 429). Primary sources 
of nutrients include leaf litter, cave crickets (Ceuthophilus spp.), 
small mammals, and other vertebrates that defecate or die in the cave. 
While the life habits of the nine invertebrates are not well known, the 
species probably prey on the eggs, larvae, or adults of other cave 
invertebrates, such as cave crickets (Mitchell 1971b, p. 250).

Subsurface Environment

    The nine Bexar County invertebrates require stable temperatures and 
constant, high humidity (Barr 1968, p. 47; Mitchell 1971b, p. 250). 
They have lost the adaptations needed to prevent desiccation in drier 
habitats (Howarth 1983, p. 368) and the ability to detect or cope with 
more extreme temperatures (Mitchell 1971a, pp. 300-301). Temperatures 
in caves are typically the average annual surface temperature with 
little variation (Howarth 1983, p. 373; Dunlap 1995, p. 76). Relative 
humidity is typically near 100 percent in caves that support 
troglobitic invertebrates (Elliott and Reddell 1989, p. 6; Zara 2010, 
pp. 9-10).
    Microhabitat is an important component of features occupied by the 
nine Bexar County karst invertebrates and has been quantified for three 
of the listed species that occur on Camp Bullis, R. exilis, R. 
infernalis, and Madla Cave meshweaver (Zara and Veni 2009, pp. 499-
505). In observations made in 13 caves, R. exilis was seldom found near 
an entrance (11 out of 147 instances), occasionally found further from 
the cave entrance in the twilight zone (typified by very little light 
and more stable humidity and temperatures than the entrance area) (44 
out of 147 instances), and more often found deeper in the caves' dark 
zones (typified by total darkness, stable humidity and temperature) (91 
out of 147 instances). The recorded microhabitats (53 instances) 
occupied by R. exilis were varied, with about 66 percent of them on top 
of the substrate and 34 percent under rocks or on the undersides of 
rocks or other materials (Zara and Veni 2009, pp. 497, 503).
    From measurements made in three caves, R. infernalis was found in 
the entrance (6 out of 23 instances) and twilight zone (10 out of 23 
instances) more often that the dark zone (7 out of 23 instances). The 
species was found under rocks 85 percent of the time (Zara and Veni 
2009, pp. 504-505).
    From 75 observations made in 2 caves, Madla Cave meshweavers were 
found 3 times in the twilight and 72 times in the dark. The species was 
always found among loose rocks or mud balls. In 117 of the 135 
instances where location in respect to substrate was recorded, they 
were underneath or on the underside of rocks. The other times they were 
on top of rocks (Zara and Veni 2009, pp. 506-512).
    During temperature extremes, the nine Bexar County invertebrates 
may retreat into small, human-inaccessible,

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interstitial spaces (mesocaverns), where the physical environment is 
more conducive to their humidity and temperature preferences (Howarth 
1983, p. 372). These species may spend the majority of their time in 
interstitial spaces, only leaving them to forage in the larger cave 
passages (Howarth 1987, p. 377). Krejca and Weckerly (2007, p. 287) 
recommended 14 surveys to determine the presence of R. exilis (one of 
the nine Bexar County invertebrates) in a cave. Krejca and Weckerly 
(2007, pp. 287-288) hypothesized that when the species are not detected 
during surveys the invertebrates are in mesocaverns. Therefore, the 
mesocaverns should be considered a priority for conservation (Krejca 
and Weckerly 2007, pp. 287-288).
    Connectivity of mesocaverns with larger features is needed to 
maintain gene flow through karst habitat, serve as a conduit for 
recolonization of features in the future if current habitat becomes 
unsuitable, provide refuge during times of extreme temperatures and low 
humidity, and allow for adaptive management of the species as new 
information becomes available. The Draft Bexar County Invertebrates 
Recovery Plan recommended good connectivity with mesocaverns for 
population dynamics of troglobites as a goal for maintaining a healthy 
karst ecosystem (Service 2008, p. B-1), but did not specify the area 
needed, because so little is known about the life-history requirements 
of these invertebrates.
    The extent to which the species use mesocaverns between or around 
caves is not fully known. White (2006, pp. 76-78) studied the 
distribution of Bexar County karst invertebrates in detail and found 
that Hilger Hole, Eagle's Nest, Root Canal, and several other caves 
within and adjacent to Camp Bullis likely functioned as a single 
habitat patch, and the species had common genetic signatures between 
caves. The farthest distance between the entrances of these caves is 
about 1.5 miles (mi) (2.4 kilometers (km)). However, the area around 
Camp Bullis is different from many of the other Bexar County caves. All 
of the Camp Bullis area caves were formed within the damage zone of a 
fault where interconnected mesocaverns and entrance-less caves occur. 
Because the area is a faults zone, there are long distances of 
connectivity between mesocaverns. In another part of Bexar County, two 
caves (Robber's Cave and Hills and Dales Pit) have entrances about 0.3 
mi (0.5 km) apart, have high similarity (although not identical) 
genetics of Madla Cave meshweavers (White 2006, pp. 97-99), and have 
mesocaverns that are connected (White, SWCA, pers. comm., 2010). Many 
of the caves where the nine Bexar County invertebrates occur are 
interconnected with mesocaverns, and some caves have no entrances.
    The northern portion of Bexar County is located on the Edwards 
Plateau, a broad, flat expanse of Cretaceous carbonate rock that ranges 
in elevation from 1,100 feet (ft) (335 meters (m)) to 1,900 ft (580 m) 
(Veni 1988, p. 11; Soil Conservation Service 1966, p. 1). This portion 
of the Edwards Plateau is dissected by numerous small streams. To the 
southeast of the Edwards Plateau lies the Balcones Fault Zone, a 16-mi 
(25-km) wide fault zone that extends from the northeast corner of the 
County to the western County line. The many streams and karst features 
of this zone recharge the Edwards Aquifer.
    The principal cave-containing rock units of the Edwards Plateau are 
the upper Glen Rose Formation, Edwards Limestone, Austin Chalk, and 
Pecan Gap Chalk (Veni 1988, p. 24). The Edwards Limestone accounts for 
one-third of the cavernous rock in Bexar County, and contains 60 
percent of the caves. The Austin Chalk outcrop is second to the Edwards 
in total number of caves. In Bexar County, the outcrop of the upper 
member of the Glen Rose Formation accounts for approximately one-third 
of the cavernous rock, but only 12.5 percent of Bexar County caves 
(Veni 1988, p. 15). In Bexar County, the Pecan Gap Chalk, while 
generally not cavernous, has a greater than expected density of caves 
and passages (Veni 1988, p. 24).
    Veni (1994, pp. 68-76) delineated six karst areas (karst fauna 
regions (KFRs)) within Bexar County: Stone Oak, UTSA (University of 
Texas at San Antonio), Helotes, Government Canyon, Culebra Anticline, 
and Alamo Heights (Figure 1). These KFRs are bounded by geological or 
geographical features that may represent obstructions to the movement 
(on a geologic time scale) of troglobites, which has resulted in the 
present-day distribution of endemic (restricted to a given region) 
karst invertebrates in the Bexar County area. The basis for these 
divisions is the lack of continuity between caves that may form 
complete barriers or significant restrictions to migration of 
troglobites over modern or geologic time scales. These discontinuities 
are defined based on characteristics that affect cave development 
combined with the geologic history of the area.
BILLING CODE 4310-55-P

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    Figure 1. Karst Fauna Regions and Karst Zones in Bexar County, 
Texas.
[GRAPHIC] [TIFF OMITTED] TP22FE11.000

BILLING CODE 4310-55-C
    The KFRs were analyzed using the current range of 19 troglobitic 
species, including the 9 Bexar County invertebrates (Veni 1994, pp. 72-
73). The KFRs are important because they are used to establish recovery 
criteria for individual species in the Draft Bexar County Karst 
Invertebrate Recovery Plan. To meet those criteria, specified numbers 
of preserves of a given quality

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must be protected within each KFR in which they occur.
    Also, the six KFRs were delineated by Veni (2003, pp. 10-18) into 
five zones that reflect the likelihood of finding a karst feature that 
will provide habitat for the endangered invertebrates, based on 
geology, distribution of known caves, distribution of cave fauna, and 
primary factors that determine the presence, size, shape, and extent of 
caves with respect to cave development. As described by Veni (2003, pp. 
10-18), these five zones are defined as:
    Zone 1: Areas known to contain one or more of the nine Bexar County 
invertebrates (areas where species are present).
    Zone 2: Areas having a high probability of suitable habitat for the 
invertebrates (areas that may contain one or more invertebrates, but 
have not been fully surveyed).
    Zone 3: Areas that probably do not contain the invertebrates 
(because there is very little suitable karst habitat).
    Zone 4: Areas that require further research, but are generally 
equivalent to Zone 3, although they may include sections that could be 
classified as Zone 2 or 5 (areas where less is known about the karst 
structure than with Zone 3).
    Zone 5: Areas that do not contain the Bexar County invertebrates 
(areas with units of rock that do not contain karst habitat).

Surface Environment

Animal Community

Cave Crickets

    Cave crickets are a critical source of nutrient input for karst 
ecosystems (Barr 1968, p. 48; Reddell 1993, p. 2). Cave crickets in the 
genus Ceuthophilus occur in most caves in Texas (Reddell 1966, pp. 32-
34). Sensitive to temperature extremes and dry environments, cave 
crickets forage on the surface at night and roost underground during 
the day. Taylor et al. (2005, p. 103) found that cave crickets lay 
their eggs in the cave, providing food for a variety of karst species 
(Mitchell 1971b, p. 250). Some karst species also feed on cave cricket 
feces (Barr 1968, p. 51; Poulson et al. 1995, p. 226), and on adults 
and juveniles directly (Elliott 1994a, p. 16). Cave crickets are 
scavengers or detritivores (animals that feed on decomposing organic 
matter), feeding on dead insects, carrion, and some fruits, but not on 
foliage (Elliott 1994a, p. 16; Taylor et al. 2004, p. 29).
    Elliott (1994a, p. 8) evaluated cave cricket foraging within 164 ft 
(50 m) of cave entrances. In a more recent study, Taylor et al. (2005, 
p. 97) found that cave crickets foraged much farther, up to 344 ft (105 
m) from a cave entrance.

Other Surface Animals

    Many central Texas caves with endangered invertebrate species are 
frequented by mammals, reptiles, and amphibians (Reddell 1967, p. 184). 
Although there are no studies documenting the role of mammals in 
central Texas cave ecology, the presence of a large amount of animal 
materials (such as scat, nesting materials, and dead bodies) indicates 
they are probably important sources of nutrients. In particular, 
important sources of nutrients for the cave species may be the fungus, 
microbes, and other troglophiles and troglobites that grow or feed on 
animal feces (Elliott 1994b, p. 16; Gounot 1994, p. 204).
    For predatory troglobites (such as the nine Bexar County karst 
invertebrates), invertebrates that accidently occur in the caves may 
also be an important nutrient source (Hopper 2000, p. 2349). Documented 
accidental species include snails, earthworms, terrestrial isopods 
(commonly known as pillbugs or potato bugs), scorpions, spiders, mites, 
collembola (primitive wingless insects that are commonly known as 
springtails), thysanura (commonly known as bristletails and 
silverfish), harvestmen (commonly known as daddy-long-legs), ants, 
leafhoppers, thrips, beetles, weevils, moths, and flies (Reddell 1965, 
pp. 146-179; 1966, pp. 27-29; 1999, pp. 40-41).
    The imported red fire ant (Solenopsis invicta) (fire ant) is an 
aggressive predator, which has had a devastating and long-lasting 
impact on native ant populations and other arthropod communities 
(Vinson and Sorenson 1986, p. 17; Porter and Savignano 1990, p. 2095) 
and is a threat to the nine Bexar County invertebrates (Elliott 1994b, 
p. 15; Service 1994, pp. 63-64). Fire ants have been observed building 
nests both within and near cave entrances as well as foraging in caves, 
especially during the summer. Shallow caves inhabited by the nine Bexar 
County invertebrates make them especially vulnerable to invasion by 
fire ants and other exotic species. Fire ants have been observed 
preying on several cave species (Elliott 1994b, p. 15). Karst fauna 
that are most vulnerable to fire ant predation are the eggs, nymphs, 
and slower-moving adults (James Reddell, Texas Memorial Museum, pers. 
comm., 2006). The presence of fire ants in and around karst areas could 
have a drastic detrimental effect on the karst ecosystem through loss 
of both surface and subsurface species that are critical links in the 
food chain. Besides direct predation, fire ants threaten listed 
invertebrates by reducing the nutrient input carried in by cave 
crickets and other trogloxenes. Because fire ants are voracious, they 
can out-compete crickets for food resources (Taylor et al. 2003, pp. 
109-110), leading to a reduction in overall productivity in the caves.
    The invasion of fire ants is known to be aided by ``any disturbance 
that clears a site of heavy vegetation and disrupts the native ant 
community'' (Porter et al. 1988, p. 916). Porter et al. (1991, p. 873) 
state that control of fire ants in areas greater than 12 ac (5 ha) may 
be more effective than in smaller areas, because multiple queen fire 
ant colonies reproduce primarily by ``budding,'' where queens and 
workers branch off from the main colony and form new sister colonies. 
Maintaining large, undisturbed areas of native vegetation may also help 
sustain the native ant communities (Porter et al. 1988, p. 916; 1991, 
p. 869).
Vegetation Community
    Surface vegetation is an important element of the karst habitat for 
several reasons, including its role in providing nutrients from: (1) 
Direct flow of plant material into the karst with water; (2) habitat 
and food sources provided for the animal communities that contribute 
nutrients to the karst ecosystem (such as cave crickets, small mammals, 
and other vertebrates); and (3) roots that extend into subsurface 
areas. Surface vegetation also acts as a buffer for the subsurface 
environment against drastic changes in temperature and moisture, and 
serves to filter pollutants before they enter the karst system 
(Biological Advisory Team 1990, p. 38). In some cases, healthy native 
plant communities also help control certain exotic species (such as 
fire ants) (Porter et al. 1988, p. 916) that may compete with or prey 
upon the listed species and other species (such as cave crickets) that 
are important nutrient contributors (Elliott 1994a, pp. 95-96; Lavoie 
et al. 2007, p. 126).
    Tree roots may provide a major energy source in shallow caves 
(Howarth 1983, p. 373). Jackson et al. (1999, p. 11387) investigated 
rooting depth in 21 caves on the Edwards Plateau to assess the below-
ground vegetational community structure and the functional importance 
of roots. They observed roots of plateau live oak (Quercus fusiformis) 
penetrating up to 82 ft (25 m) into the interior of one of the caves. 
The roots of five other tree species, post oak (Q. sinuata), cedar elm 
(Ulmus crassifolia), American elm (U. americana), sugar hackberry 
(Celtis laevigata), and Ashe juniper (Juniperus asheii), penetrated to

[[Page 9877]]

below 16 ft (5 m) into caves. These are all common species in the 
plateau. Most of the caves in Bexar County are less than 20 ft (6 m) 
deep, so roots have the potential to penetrate many of them.
    Karst ecosystems are heavily reliant on surface plant and animal 
communities to maintain nutrient flows, reduce sedimentation, and 
resist exotic and invasive species. As the surface around a cave 
entrance becomes developed, native plant communities are often replaced 
with impermeable cover or exotic plants from nurseries. The abundance 
and diversity of native animals may decline due to decreased food and 
habitat combined with increased competition and predation from urban, 
exotic, and pet species. As native surface plant and animal communities 
are destroyed, food and habitat once available to trogloxenes 
decreases. It is unknown whether exotic species could contribute the 
same quantity and quality of nutrients to the karst ecosystem.

Woodland-Grassland Community

    Because of the various roles played by surface vegetation in 
maintaining the cave and karst ecosystem, including the nine Bexar 
County invertebrate species that are part of the ecosystem, we examined 
the best available scientific information to estimate the surface 
vegetation needed to support ecosystem processes. The woodland-
grassland mosaic community typical of the Edwards Plateau is a patchy 
environment composed of many different plant species. Van Auken et al. 
(1980, p. 23) studied the woody vegetation of the Edwards and Glen Rose 
formations in the southern Edwards Plateau in Bexar, Bandera, and 
Medina Counties. They encountered a total of 24 species of plants on 
the Edwards or Glen Rose geologic formations, two of the principal, 
cave-containing rock units of the Edwards Plateau.
    To maintain natural vegetation communities over the long term, 
enough individuals of each plant species must be present for successful 
reproduction. The number of reproductive individuals necessary to 
maintain a viable or self-reproducing plant population is influenced by 
needs for satisfactory germination (Menges 1995, p. 123), genetic 
variation (Bazzaz 1983, pp. 267-268; Menges 1995, p. 123; Young 1995, 
pp. 154-155), and pollination (Groom 1998, p. 487; Jennersten 1995, p. 
130; Bigger 1999, p. 239). Pavlik (1996, p. 136) stated that long-
lived, self-fertilizing, woody plants with high fecundity would be 
expected to have minimum viable population sizes in the range of 50 to 
250 reproductive individuals. Fifty reproductive individuals is a 
reasonable minimum figure for one of the dominant species of the 
community, Ashe juniper, based on reproductive profiles (Van Auken et 
al. 1979, p. 170; Van Auken et al. 1980, pp. 30-31; Van Auken et al. 
1981, pp. 1251-1253). This figure would likely be an underestimate for 
other woody species present in central Texas woodlands, because other 
woody species are more sensitive to environmental changes and do not 
meet several of the life-history criteria needed for the lowest minimal 
viable population size. Although other woody species may require 
population sizes at the higher end of the range (near 250 individuals) 
to be viable, as suggested by Pavlik (1996, p. 136), we do not have the 
data to support that contention. Therefore, on the basis of our review 
of information available to us, and after soliciting input from a 
botanist with expertise in the Edwards Plateau (Dr. Kathryn Kennedy, 
Center for Plant Conservation, pers. comm., 2002), we consider a 
minimum viable population size for individual plant species composing a 
typical oak/juniper woodland found in central Texas to be 80 
individuals per species. This estimate is based on a habitat type that, 
as a whole, is fairly mature, and on knowledge that the species are 
relatively long-lived and reproductively successful.
    Based on an analysis of recorded densities, corrected for non-
reproductive individuals, we then calculated the area needed to support 
80 mature reproductive individuals per species for the 24 species 
reported by Van Auken et al. (1980, p. 23). We determined that the 4 
highest area requirements to maintain at least 80 mature individuals 
were for species that occur at lower densities. These included 198 ac 
(80 ha) for brasil (Condalia hookeri), and approximately 80 ac (32 ha) 
for each of hoptree (Ptelea trifoliata), Mexican buckeye (Ungnadia 
speciosa), and chittamwood (Bumelia lanuginosa). Our calculations 
indicate that the area needed to maintain the seven species with the 
highest average dominance values, Ashe juniper, Texas live oak, Texas 
red oak (Quercus texana), catclaw acacia (Acacia greggii), evergreen 
sumac (Rhus virens), agarita (Mahonias trifoliata), and cedar elm 
(Ulmus crassifolia), is approximately 33 ac (13 ha). An area of 33 ac 
(13 ha) would maintain 80 reproductive individuals for 15 of the 24 
species. The area needed to maintain the nine rarest plant species 
ranges from approximately 49 to 198 ac (20 to 80 ha) with 7 of species 
in the 65 to 80 ac (26 ha to 32 ha) range.
    The Bexar County Invertebrates Draft Recovery Plan used a minimum 
viable population size of 80 individuals of the top 15 to 20 woodland 
species and recommended 80 ac (32 ha) of woodland habitat for 
establishing a high-quality preserve that maintains a diverse community 
of woody vegetation for at least 100 years (Service 2008, pp. B-9 to B-
11).
    Most literature found for central Texas native grasslands was 
descriptive and not quantitative in its treatment of species 
composition and dispersion. No literature was located that provided 
grassland species area curves or quantitative species density tables 
for the central Texas area. Two papers by Lynch (1962, p. 679; 1971, p. 
890) examined grassland species on an 8-ac (3.2-ha) tract over time 
with 123 species and high species turnover. High species turnover can 
be indicative of a habitat area which is too small; however, pre- and 
post-drought conditions may also have affected this situation. In a 
slightly more mesic grassland habitat, Robertson et al. (1997, p. 65) 
found that a 10-ac (4-ha) site captured most of the grassland species 
diversity (100 species) present, although it does not address 
population sizes and persistence in isolation, and an increase to a 14-
ac (6-ha) tract increased species representation to 140. Another paper 
on a grassland in a more westerly and drier location in central Texas 
recorded 157 taxa in a 40-ac (16-ha) enclosure between 1948 and the 
mid-1970s (Smeins et al. 1976, pp. 24-25).
    The Draft Bexar County Invertebrates Recovery Plan recommends that 
10 ac (4 ha) of total grassland area within a woodland-grassland mosaic 
is needed in the preserves. This figure was derived by adding a 2 ac 
(0.8 ha) margin to the 8 ac (3 ha) tract (see previous paragraph) with 
typical species diversity based on Lynch's (1962, p. 679; 1971, p. 890) 
studies to provide additional area that would aid community stability 
if the high species turnover there was not due to regional drought 
influences alone.
Edge Effects
    To maintain a viable vegetative community, including woodland and 
grassland species, an undisturbed area is needed to shield the core 
habitat from impacts associated with edge effects or disturbance from 
adjacent urban development (Lovejoy et al. 1986, p. 284; Yahner 1988, 
pp. 333-334). In this context, edge effects refer to the adverse 
changes to natural communities (primarily from increases in invasive 
species and pollutants, and changes in

[[Page 9878]]

microclimates) from nearby areas that have been modified for human 
development.
    The changes caused by edge effects can occur rapidly. For example, 
vegetation 6.6 ft (2 m) from a newly created edge can be altered within 
days (Lovejoy et al. 1986, pp. 258-259). Edges may allow invasive plant 
species to gain a foothold where the native vegetation had previously 
prevented their spread (Saunders et al. 1991, p. 23; Kotanen et al. 
1998, p. 669; Suarez et al. 1998, pp. 2041-2042; Meiners and Steward 
1999, p. 261). When plant species composition is altered as a result of 
an edge effect, changes also occur in the surface animal communities 
(Lovejoy and Oren 1981, p. 11; Harris 1984, pp. 72, 74; Mader 1984, p. 
90; Thompson 1985, pp. 526-527; Lovejoy et al. 1986, pp. 283-284; 
Yahner 1988, p. 335; Fajer et al. 1989, p. 1199; Kindvall and Ahlen 
1992, pp. 523, 528; Tscharntke 1992, pp. 534-535; Hanski 1995, p. 204; 
Lindenmayer and Possingham 1995, p. 236; Bowers et al. 1996 p. 188; 
Hill et al. 1996, p. 726; Kozlov 1996, pp. 99-100, 102; Kuussaari et 
al. 1996, pp. 791, 798; Turner 1996, p. 204; Mankin and Warner 1997, 
pp. 140-142; Burke and Nol 1998, p. 96; Didham 1998, p. 404; Suarez et 
al. 1998, p. 2041; Crist and Ahern 1999, p. 687; Kindvall 1999, p. 
181). Changes in plant and animal species composition because of edge 
effects may unnaturally change the nutrient cycling processes required 
to support cave and karst ecosystem dynamics. To minimize edge effects, 
the area needed to support a native plant and animal community must 
have a sufficient perimeter area to protect it.
    One recommendation for protecting forested areas from edge effects 
that are in proximity to clear-cut areas is use of the ``three tree 
height'' approach (Harris 1984, p. 110) for estimating the width of the 
perimeter area needed. We used this general rule to estimate the width 
of perimeter areas needed to protect the habitat areas. The average 
height of native mature trees in the Edwards woodland association in 
Texas ranges from 10 to 30 ft (3 to 9 m) (Van Auken et al. 1979, p. 
177). Applying the ``three tree height'' general rule, and using the 
average value of 21.6 ft (6.6 m) for tree height, we estimated that a 
perimeter width of at least 66 ft (20 m) is needed around a core 
habitat area to protect the vegetative community from edge effects. 
Based on this rule, 10 ac (4 ha) is necessary to protect a 79-ac (32-
ha) circular core area. We recognize that the ``three tree height'' 
approach described by Harris (1984, pp. 110-111) was based on the 
distance that effects of storm events (``wind-throw'') from a 
surrounding clear-cut ``edge'' will penetrate into an old-growth forest 
stand. Although the effects of edge on woodland/grassland mosaic 
communities have not been well studied, we believe that the ``three 
trees height'' recommendation is the best available peer-reviewed 
science to protect woodland areas from edge effects (Dr. Kathryn 
Kennedy, Center for Plant Conservation, pers. comm., 2003).
    Animal communities also should be protected from impacts associated 
with edge effects or disturbance from adjacent urban development. Edges 
can act as a barrier to dispersal of birds and mammals (Yahner 1988, p. 
336; Hansson 1998, p. 55). Invertebrate species are affected by edges. 
Mader et al. (1990, p. 214) found that carabid beetles and lycosid 
spiders avoided crossing unpaved roads that were even smaller than 9 ft 
(3 m) wide. Saunders et al. (1990, p. 23) suggested that as little as 
330 ft (100 m) of agricultural fields may be a complete barrier to 
dispersal for invertebrates and some species of birds. In general, for 
animal communities, species need buffers of 164 to 330 ft (50 to 100 m) 
or greater to ameliorate edge effects (Lovejoy et al. 1986, p. 263; 
Wilcove et al. 1986, pp. 249-250; Laurance 1991, p. 206; Laurance and 
Yensen 1991, pp. 78-79; Kapos et al. 1993, p. 425; Andren 1995, p. 237; 
Reed et al. 1996, p. 1102; Burke and Nol 1998, p. 96; Didham 1998, p. 
397; Suarez et al. 1998, p. 2047).
    Nonnative fire ants are known to be harmful to many species of 
invertebrates and vertebrates. In coastal southern California, Suarez 
et al. (1998, p. 2041) found that densities of the exotic Argentine ant 
(Linepithema humile), which has similar life-history and ecological 
requirements to the red imported fire ant (Dr. Richard Patrock, 
University of Texas at Austin, pers. comm., 2003), are greatest near 
disturbed areas. Native ant communities tended to be more abundant in 
native vegetation and less abundant in disturbed areas. Based on the 
association of the Argentine ant and distance to the nearest edge in 
urban areas, core areas may only be effective at maintaining natural 
populations of native ants when there is a buffer area of at least 660 
ft (200 m) (Suarez et al. 1998, pp. 2050, 2052).
    We do not have site-specific information on the area needed to 
maintain populations of animal species, including cave crickets, found 
in central Texas. Therefore, we are relying on information from other 
areas. Based on that information, animal communities should be 
protected by areas of 164 to 330 ft (50 to 100 m) or greater to 
ameliorate edge effects, and by areas of 660 ft (200 m) to protect 
against the effects of fire ants. From this data, we determined that a 
distance of 330 ft (100 m), in addition to the 344-ft (105-m) cave 
cricket foraging area, would be the minimum needed to protect the cave 
cricket foraging area from the effects of edge and nonnative species 
invasions.
Dispersal
    The ability of individuals to move between preferred habitat 
patches is essential for colonization and population viability (Eber 
and Brandl 1996, p. 621; Fahrig and Merriam 1994, p. 52; Hill et al. 
1996, pp. 725-726; Kattan et al. 1994, pp. 139, 143; Kindvall 1999, p. 
172; Kozlov 1996, pp. 95-96; Kuussaari et al. 1996, p. 791; Turner 
1996, p. 205). Patch shapes allowing connection with the highest number 
of neighboring patches increase the likelihood that a neighboring patch 
will be occupied (Fahrig and Merriam 1994, p. 53; Kindvall 1999, p. 
172; Kuussaari et al. 1996, p. 791; Tiebout and Anderson 1997, p. 620). 
If movement among populations is restricted and a population is 
isolated, the habitat patch size must be large enough to ensure that 
the population can survive (Fahrig and Merriam 1994, p. 54).
Summary
    The conservation of the endangered Bexar County karst invertebrates 
depends on a self-sustaining karst ecosystem, surface and subsurface 
drainage basins to maintain adequate quantity and quality of moisture, 
and a viable surface animal and plant community for nutrient input and 
protection of the subsurface from adverse impacts. The area needed to 
conserve such an ecosystem includes a minimum core area of 100 ac (40 
ha) of healthy, native woodland-grassland mosaic comprised of 80 ac (32 
ha) of woodland, 10-ac (4-ha) of grassland, and a 10-ac (4-ha) buffer 
to protect against edge effects. The 100-ac (40-ha) core area should 
encompass the surface and subsurface drainage basins of the occupied 
feature, the 344-ft (105-m) cave cricket foraging distance from the 
entrance to the cave, and a 330-ft (100-m) distance from the cave 
cricket area to protect against edge effects.

Listed Bexar County Invertebrates' Distribution

    By 2000, about 400 caves were known from Bexar County (SWCA 2000). 
Of the 400 caves, 57 were known to contain 1 or more of the 9 Bexar 
County invertebrates at the time the species

[[Page 9879]]

were listed in 2000 (65 FR 81419; December 26, 2000). Currently, we are 
aware of 89 caves in Bexar County that contain 1 or more of the 9 Bexar 
County invertebrates (Table 1).

  Table 1--Caves Known To Contain One or More of the Nine Listed Bexar
                       County Karst Invertebrates
 [We include subspecies in this table in order to show genetic diversity
                                by cave]
------------------------------------------------------------------------
Species ( of caves)          Cave name            Karst fauna
------------------------------------------------------------------------
Rhadine exilis (51).........  40 mm Cave *.............  Stone Oak.
                              B-52 Cave *..............
                              Backhole *...............
                              Banzai Mud Dauber Cave *.
                              Black Cat Cave...........
                              Blanco Cave..............
                              Boneyard Pit *...........
                              Bunny Hole *.............
                              Constant Sorrow Cave *...
                              Cross the Creek Cave *...
                              Dos Viboras Cave *.......
                              Eagle's Nest Cave *......
                              Hairy Tooth Cave.........
                              Headquarters Cave *......
                              Hilger Hole *............
                              Hold-Me-Back Cave *......
                              Hornet's Last Laugh Pit..
                              Isocow Cave..............
                              Kick Start Cave..........
                              MARS Pit *...............
                              MARS Shaft *.............
                              Pain in the Glass Cave *.
                              Peace Pipe Cave *........
                              Platypus Pit *...........
                              Poor Boy Baculum Cave *..
                              Ragin' Cajun Cave........
                              Root Canal Cave *........
                              Root Toupee Cave *.......
                              Springtail Crevice.......
                              Strange Little Cave *....
                              Up the Creek Cave *......
                             -------------------------------------------
                              Christmas Cave...........  Helotes.
                              Helotes Blowhole.........
                              Helotes Hilltop Cave.....
                              Logan's Cave.............
                              unnamed cave \1/2\ mile
                               N. of Helotes.
                             -------------------------------------------
                              Creek Bank Cave..........  Government
                                                          Canyon.
                              Government Canyon Bat
                               Cave.
                              Lithic Ridge Cave........
                              Pig Cave.................
                              San Antonio Ranch Pit....
                              Tight Cave...............
                             -------------------------------------------
                              Hills and Dales Pit......  UTSA.
                              John Wagner Ranch Cave
                               No. 3.
                              Kamikazi Cricket Cave....
                              La Cantera Cave No. 1....
                              La Cantera Cave No. 2....
                              Mastodon Pit.............
                              Robber's Cave............
                              Three Fingers Cave.......
                              Young Cave No. 1.........
                             -------------------------------------------
R. infernalis ewersi (3)....  Flying Buzzworm Cave *...  Stone Oak.
                              Headquarters Cave *......
                              Low Priority Cave *......
                             -------------------------------------------
R. infernalis new subspecies  Braken Bat Cave..........  Culebra
 (9).                         Caracol Creek Coon Cave..   Anticline.
                              Game Pasture Cave No. 1..
                              Isopit...................
                              King Toad Cave...........
                              Max and Roberts Cave.....
                              Obvious Little Cave......
                              Stevens Ranch Trash Hole
                               Cave.

[[Page 9880]]

 
                              Wurzbach Bat Cave........
                             -------------------------------------------
R. infernalis infernalis      Bone Pile Cave...........  Government
 (28).                        10 K Cave................   Canyon.
                              Canyon Ranch Pit.........
                              Continental Park Cave....
                              Dancing Rattler Cave.....
                              Fat Man's Nightmare Cave.
                              Government Canyon Bat
                               Cave.
                              Hackberry Sink...........
                              Lithic Ridge Cave........
                              Pig Cave.................
                              San Antonio Ranch Pit....
                              Scenic Overlook Cave.....
                              Sure Sink................
                              Surprise Sink............
                             -------------------------------------------
                              Christmas Cave...........  Helotes.
                              Helotes Blowhole.........
                              Logan's Cave.............
                              Madla's Cave.............
                              Madla's Drop Cave........
                              Sir Doug's Cave..........
                             -------------------------------------------
                              Genesis Cave.............  Stone Oak.
                             -------------------------------------------
                              John Wagner Ranch Cave     UTSA.
                               No. 3.
                              Kamikazi Cricket Cave....
                              Mattke Cave..............
                              Robber's Cave............
                              Scorpion Cave............
                              Three Fingers Cave.......
                              Crownridge Canyon Cave...
                             -------------------------------------------
Helotes mold beetle (8).....  San Antonio Ranch Pit....  Government
                              Scenic Overlook Cave.....   Canyon.
                              Tight Cave...............
                             -------------------------------------------
                              Christmas Cave...........  Helotes.
                              Helotes Hilltop Cave.....
                              Unnamed Cave \1/2\ mile N
                               of Helotes.
                              Unnamed Cave \1/2\ mile
                               NE of Helotes.
                             -------------------------------------------
                              Unnamed Cave 5 miles NE    UTSA.
                               of Helotes.
                             -------------------------------------------
Cokendolpher Cave harvestman  Robber Baron Cave........  Alamo Heights.
 (1).
                             -------------------------------------------
Robber Baron Cave meshweaver  Robber Baron Cave          Alamo Heights.
 (2).                          meshweaver (2).
                              OB3......................
                             -------------------------------------------
Madla Cave meshweaver (20)..  Christmas Cave...........  Helotes.
                              Madla's Cave.............
                              Madla's Drop Cave........
                              Helotes Blowhole.........
                              Helotes Hilltop Cave.....
                             -------------------------------------------
                              Headquarters Cave *......  Stone Oak.
                             -------------------------------------------
                              Breathless Cave..........  UTSA.
                              Feature No. 50...........
                              Hills and Dales Pit......
                              John Wagner Ranch Cave
                               No. 3.
                              La Cantera Cave No. 1....
                              Robber's Cave............
                              Unnamed Cave Helotes Area
                             -------------------------------------------
                              Fat Man's Nightmare Cave.  Government
                                                          Canyon.
                              Lithic Ridge Cave........
                              Lost Pothole.............

[[Page 9881]]

 
                              Pig Cave.................
                              San Antonio Ranch Pit....
                              Scenic Overlook Cave.....
                              Surprise Sink............
                             -------------------------------------------
Braken Bat Cave.............  Braken Bat Cave..........  Culebra
                                                          Anticline.
                             -------------------------------------------
Government Canyon...........  Government Canyon Bat      Government.
                               Cave.
                             -------------------------------------------
Government Canyon...........  Government Canyon Bat      Government.
                               Cave.
                              Surprise Sink............
------------------------------------------------------------------------
* Cave located on Camp Bullis.

Previous Federal Actions

    We published a proposed rule to list the nine Bexar County karst 
invertebrate species as endangered in the Federal Register on December 
30, 1998 (63 FR 71855). On November 1, 2000, the Center for Biological 
Diversity filed a complaint against the Service alleging that we 
exceeded our 1-year obligation to publish a final listing rule and make 
a determination whether to designate critical habitat for the nine 
Bexar County karst invertebrates. We published a final listing rule on 
December 26, 2000 (65 FR 81419). In the final listing rule, we 
determined that critical habitat designation was prudent. On August 27, 
2002, we proposed that 25 units encompassing approximately 9,516 ac 
(3,857 ha) in Bexar County, Texas, be designated as critical habitat 
for the 9 karst invertebrates (67 FR 55063). The final critical habitat 
rule, designating approximately 1,063 ac (431 ha) in 22 units, was 
published on April 8, 2003 (68 FR 17155).
    On July 17, 2007, the Center for Biological Diversity, Citizens 
Alliance for Smart Expansion, and Aquifer Guardians in Urban Areas 
provided us with a 60-day notice of intent to sue on the final critical 
habitat rule. On January 14, 2009, the plaintiffs (CBD v. FWS, case 
number 1:09-cv-00031-LY) filed suit in Federal Court (Western District 
of Texas) alleging that the Service failed to use the best available 
science and incorrectly made exclusions according to sections 3(5)(A) 
and 4(b)(2) of the Act. On December 18, 2009, the parties filed a 
settlement agreement where we agreed to submit a revised proposed 
critical habitat determination for publication in the Federal Register 
on or before February 7, 2011, and a final revised determination by 
February 7, 2012. This proposed rule is published in accordance with 
that agreement.
    On July 8, 2010, we received a petition from Capital Foresight 
Limited Partnership to revise designated critical habitat for Rhadine 
exilis by removing Unit 13. The petitioner alleges that the original 
specimens collected from Black Cat Cave were never positively 
identified as R. exilis, another species of Rhadine with a slender body 
form similar to R. exilis occurs in a cave a short distance from Black 
Cat Cave that is likely connected by mesocaverns, and that two species 
of Rhadine with similar body forms have never been documented to occur 
in the same location. In addition, the petitioner asserts that drinking 
water is leaking into Black Cat Cave and that the habitat has been 
highly degraded by the Bulverde Road rending the area no longer 
suitable for conservation of the species. In reference to the 
petitioner's claims, more information is needed for us to make a 
determination. Information in our files indicates that a species expert 
has identified the original specimen collected from Black Cat Cave as 
R. exilis (T. Barr, pers. comm., 2010). At this time, we find that the 
petitioner presents substantial scientific or commercial information 
indicating that revising critical habitat for R. exilis may be 
warranted, but more information is needed. Therefore, with the 
publication of this rule, we are initiating a review to determine if 
revising critical habitat for R. exilis is warranted. For this proposed 
critical habitat rule, we believe that Unit 13 continues to meet the 
definition of critical habitat as discussed in the Criteria Used to 
Identify Critical Habitat section below. Thus, Unit 13 continues to be 
part of this proposed critical habitat rule, but changes may be made in 
the final rule based upon new information. This document constitutes 
our 90-day finding on the petitioned action. We request public comment 
on this finding. We will issue a 12-month finding on the petition in 
conjunction with the final critical habitat rule for the nine Bexar 
County invertebrates, which will address whether the petitioned action 
is warranted, as provided in section 4(b)(3)(B) of the Act.

Critical Habitat

Background

    Critical habitat is defined in section 3 of the Act as:
    (1) The specific areas within the geographical area occupied by the 
species, at the time it is listed in accordance with the Act, on which 
are found those physical or biological features
    (a) Essential to the conservation of the species and
    (b) Which may require special management considerations or 
protection; and
    (2) Specific areas outside the geographical area occupied by the 
species at the time it is listed, upon a determination that such areas 
are essential for the conservation of the species.
    Conservation, as defined under section 3 of the Act, means to use 
and the use of all methods and procedures that are necessary to bring 
an endangered or threatened species to the point at which the measures 
provided under the Act are no longer necessary. Such methods and 
procedures include, but are not limited to, all activities associated 
with scientific resources management such as research, census, law 
enforcement, habitat acquisition and maintenance, propagation, live 
trapping, and transplantation, and, in the extraordinary case where 
population pressures within a given ecosystem cannot be otherwise 
relieved, may include regulated taking.
    Critical habitat receives protection under section 7 of the Act 
through the

[[Page 9882]]

prohibition against Federal agencies carrying out, funding, or 
authorizing actions likely to result in the destruction or adverse 
modification of critical habitat. Section 7(a)(2) requires consultation 
on Federal actions that may affect critical habitat. The designation of 
critical habitat does not affect land ownership or establish a refuge, 
wilderness, reserve, preserve, or other conservation area. Such 
designation does not allow the government or public to access private 
lands. Such designation does not require implementation of restoration, 
recovery, or enhancement measures by non-Federal landowners. Where a 
landowner seeks or requests Federal agency funding or authorization for 
an action that may affect a listed species or critical habitat, the 
consultation requirements of section 7(a)(2) would apply, but even in 
the event of a destruction or adverse modification finding, Federal 
action agency's and the applicant's obligation is not to restore or 
recover the species, but to implement reasonable and prudent 
alternatives to avoid destruction or adverse modification of critical 
habitat.
    For inclusion in a critical habitat designation, the habitat within 
the geographical area occupied by the species at the time it was listed 
must contain the physical and biological features essential to the 
conservation of the species, and be included only if those features may 
require special management considerations or protection. Critical 
habitat designations identify, to the extent known using the best 
scientific and commercial data available, habitat areas that provide 
essential life cycle needs of the species (areas on which are found the 
physical and biological features laid out in the appropriate quantity 
and spatial arrangement for the conservation of the species). Under the 
Act and regulations at 50 CFR 424.12, we can designate critical habitat 
in areas outside the geographical area occupied by the species at the 
time it is listed only when we determine that those areas are essential 
for the conservation of the species and that designation limited to 
those areas occupied at the time of listing would be inadequate to 
ensure the conservation of the species.
    Section 4 of the Act requires that we designate critical habitat on 
the basis of the best scientific and commercial data available. 
Further, our Policy on Information Standards under the Endangered 
Species Act (published in the Federal Register on July 1, 1994 (59 FR 
34271)), the Information Quality Act (section 515 of the Treasury and 
General Government Appropriations Act for Fiscal Year 2001 (Pub. L. 
106-554; H.R. 5658)), and our associated Information Quality 
Guidelines, provide criteria, establish procedures, and provide 
guidance to ensure that our decisions are based on the best scientific 
data available. They require our biologists, to the extent consistent 
with the Act and with the use of the best scientific data available, to 
use primary and original sources of information as the basis for 
recommendations to designate critical habitat.
    When we are determining which areas should be designated as 
critical habitat, our primary source of information is generally the 
information developed during the listing process for the species. 
Additional information sources may include the recovery plan for the 
species, articles in peer-reviewed journals, conservation plans 
developed by States and counties, scientific status surveys and 
studies, biological assessments, or other unpublished materials and 
expert opinion or personal knowledge.
    Habitat is often dynamic, and species may move from one area to 
another over time. Climate change will be a particular challenge for 
biodiversity because the interaction of additional stressors associated 
with climate change and current stressors may push species beyond their 
ability to survive (Lovejoy 2005, pp. 325-326). The synergistic 
implications of climate change and habitat fragmentation are the most 
threatening facet of climate change for biodiversity (Hannah et al. 
2005, p. 4). Current climate change predictions for terrestrial areas 
in the Northern Hemisphere indicate warmer air temperatures, more 
intense precipitation events, and increased summer continental drying 
(Field et al. 1999, pp. 1-3; Hayhoe et al. 2004, p. 12422; Cayan et al. 
2005, p. 6; Intergovernmental Panel on Climate Change (IPCC) 2007, p. 
1181). Climate change may lead to increased frequency and duration of 
severe storms and droughts (Golladay et al. 2004, p. 504; McLaughlin et 
al. 2002, p. 6074; Cook et al. 2004, p. 1015).
    Furthermore, we recognize that critical habitat designated at a 
particular point in time may not include all of the habitat areas that 
we may later determine are necessary for the recovery of the species. 
For these reasons, a critical habitat designation does not signal that 
habitat outside the designated area is unimportant or may not be 
required for recovery of the species. Areas that are important to the 
conservation of the species, but are outside the critical habitat 
designation, will continue to be subject to conservation actions we 
implement under section 7(a)(1) of the Act. Areas that support 
populations are also subject to the regulatory protections afforded by 
the section 7(a)(2) jeopardy standard, as determined on the basis of 
the best available scientific information at the time of the agency 
action. Federally funded or permitted projects affecting listed species 
outside their designated critical habitat areas may still result in 
jeopardy findings in some cases. Similarly, critical habitat 
designations made on the basis of the best available information at the 
time of designation