Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for Seven Bexar County, TX, Invertebrate Species
Federal RegisterApr 8, 2003
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
RIN 1018-AI47
Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for Seven Bexar County, TX, Invertebrate Species
AGENCY:
Fish and Wildlife Service, Interior.
ACTION:
Final rule.
SUMMARY:
We, the U.S. Fish and Wildlife Service (Service), designate critical habitat for seven endangered invertebrate species found in Bexar County, Texas, pursuant to the Endangered Species Act of 1973, as amended (Act). The critical habitat designation totals approximately 431 hectares (1,063 acres) in 22 units. Section 7 of the Act requires Federal agencies to ensure, in consultation with the Service, that actions they authorize, fund, or carry out are not likely to result in the destruction or adverse modification of critical habitat. Section 4 of the Act requires us to consider economic and other impacts when specifying any particular area as critical habitat. We solicited data and comments from the public on all aspects of the proposed rule, including data on economic and other impacts of the designation. As a result of comments and information received, we are not designating critical habitat as originally proposed for two species that occur entirely on State-owned lands that are subject to a conservation plan.
DATES:
This rule becomes effective on May 8, 2003.
ADDRESSES:
Comments and materials received, as well as supporting documentation used in the preparation of this final rule, are available for public inspection, by appointment, during normal business hours at the Austin Ecological Services Field Office, U.S. Fish and Wildlife Service, 10711 Burnet Road, Suite 200, Austin, Texas 78758.
FOR FURTHER INFORMATION CONTACT:
Robert Pine, Supervisor, U.S. Fish and Wildlife Service, Austin Ecological Services Field Office, at the above address (telephone 512/490-0057; facsimile 512/490-0974).
SUPPLEMENTARY INFORMATION:
Background
The seven species for which we are designating critical habitat in this rulemaking 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 a honeycomb.
As a result of climatic changes beginning two million years ago and lasting until ten thousand years ago, invertebrate species colonized caves and other subterranean voids (Barr 1968; Mitchell and Reddell 1971; Elliott and Reddell 1989). Species that dwell exclusively in caves and other subterranean voids are referred to as “troglobites.” Through faulting and canyon downcutting, the karst terrain colonized by these species along the Balcones Fault Zone (a zone approximately 25 kilometers (km) in width, extending from the northeast corner of Bexar County to the western edge of the County) became increasingly dissected, creating “islands” of karst and barriers to dispersal. These “islands” isolated troglobitic populations from each other, probably resulting in further speciation.
The following nine Bexar County, Texas, troglobitic invertebrate species were listed as endangered on December 26, 2000 (65 FR 81419): spider (no common name) (
Cicurina venii
), Robber Baron Cave harvestman (
Texella cokendolpheri
), vesper cave spider (
Cicurina vespera
), Government Canyon cave spider (
Neoleptoneta microps
), Madla's cave spider (
Cicurina madla
), Robber Baron cave spider (
Cicurina baronia
), beetle (no common name) (
Rhadine exilis
), beetle (no common name) (
Rhadine infernalis
), and Helotes mold beetle (
Batrisodes venyivi
). These are karst dwelling species of local distribution in north and northwest Bexar County. They spend their entire lives underground.
Since publication of the listing final rule, the common names for the following six arachnid species have been changed as a result of a meeting of the Committee on Common Names of Arachnids of the American Arachnological Society in 2000. Accordingly, we are changing the common names of the species currently in the list of Endangered and Threatened Wildlife (50 CFR 17.11) as Robber Baron Cave harvestman, Robber Baron cave spider, Madla's cave spider, vesper cave spider, Government Canyon cave spider, and one with no common name (
Cicurina venii
) to Cokendolpher cave harvestman, Robber Baron Cave meshweaver, Madla Cave meshweaver, Government Canyon Bat Cave meshweaver, Government Canyon Bat Cave spider, and Braken Bat Cave meshweaver, respectively.
Individuals of the listed species are small, ranging in length from 1 millimeter (0.039 inch (in)) to 1 centimeter (0.39 in). They are eyeless, or essentially eyeless, and most lack pigment. Low quantities of food in caves have caused adaptations in these species, including low metabolism, long legs for efficient movement, and loss of eyes, possibly as an energy-saving trade-off (Howarth 1983). Survival may be possible from months to years with little or no food (Howarth 1983). Adult
Cicurina
spiders have survived in captivity without food for about 4 months (James Cokendolpher, Museum of Texas Tech University, pers. comm. 2002).
Although little is known about the life history of listed Texas troglobitic invertebrates, they are believed to live for longer than 1 year. This belief is based, in part, on the amount of time some juveniles have been kept in captivity without maturing (Veni and Associates 1999; James Reddell, Texas Memorial Museum, pers. comm. 2000). For example, James Cokendolpher (Museum of Texas Tech University, pers. comm. 2002) maintained a juvenile troglobitic
Cicurina
spider from May 1999 through April 2002. Reproductive rates of troglobites are typically low (Poulson and White 1969; Howarth 1983). According to surveys conducted by Culver (1986), Elliott (1994a), and Hopper (2000), population sizes of troglobitic invertebrates are typically small, with most species known from only a few specimens (Culver
et al.
2000).
As described below, the primary habitat requirements of these species include: (1) Subterranean spaces in karst with stable temperatures, high humidities (near saturation), and suitable substrates (for example, spaces between and underneath rocks suitable for foraging and sheltering); and (2) a healthy surface community of native plants and animals that provide nutrient input and, in the case of native plants, act to buffer the karst ecosystem from adverse effects (for example, invasions of nonnative species, contaminants, and fluctuations in temperature and humidity). These karst invertebrates require stable temperatures and constant, high humidity (Barr 1968; Mitchell 1971a) because they are vulnerable to desiccation in drier habitats (Howarth 1983) or cannot detect or cope with more extreme temperatures (Mitchell 1971a). Temperatures in caves typically remain at the average annual surface temperature, with little variation
(Howarth 1983; Dunlap 1995). Relative humidity is typically near 100 percent in caves that support troglobitic invertebrates (Elliott and Reddell 1989). During temperature extremes, the listed species may retreat into small interstitial spaces (human-inaccessible) connected to a cave, where the physical environment provides the required humidity and temperature levels (Howarth 1983). These species may spend the majority of their time in such retreats, only leaving them to forage in the larger cave passages (Howarth 1987).
Since sunlight is absent or present in extremely low levels in caves, most karst ecosystems depend on nutrients derived from the surface either directly (organic material brought in by animals, washed in, or deposited through root masses) or indirectly through 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; Poulson and White 1969; Howarth 1983; Culver 1986). Primary sources of nutrients include leaf litter, cave crickets, small mammals, and other vertebrates that defecate or die in the cave.
As described in our final rule to list the nine species (65 FR 81419), the continuing expansion of the human population in karst terrain constitutes the primary threat to the species through: (1) Destruction or deterioration of habitat by construction; (2) filling of caves and karst features and loss of permeable cover; (3) contamination from septic effluent, sewer leaks, runoff, pesticides, and other sources; (4) exotic species, especially nonnative fire ants (
Solenopsis invicta
); and (5) vandalism.
Karst in Bexar County
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 335.5 meters (m) (1,100 feet (ft)) to 579.5 m (1,900 ft) (Veni 1988; Soil Conservation Service 1962). This portion of the Plateau is dissected by numerous small streams and is drained by Cibolo Creek and Balcones Creek. To the southeast of the Plateau lies the Balcones Fault Zone, a 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). The Edwards Limestone accounts for one-third of the cavernous rock in Bexar County and contains 60 percent of the caves, making it the most cavernous unit in the County. 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). In Bexar County, the Pecan Gap Chalk, while generally not cavernous, has a greater than expected density of caves and passages (Veni 1988).
Veni (1994) delineated six karst areas within Bexar County. The regions were named after places within their boundaries. These karst fauna regions 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.
These areas have been delineated by Veni (1994) into five zones that reflect the likelihood of finding a karst feature that will provide habitat for the endangered Bexar County 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. These five zones are defined as:
Zone 1:
Areas known to contain one or more of the nine endangered karst invertebrates;
Zone 2:
Areas having a high probability of suitable habitat for the invertebrates;
Zone 3:
Areas that probably do not contain the invertebrates;
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 zone 5; and
Zone 5:
Areas that do not contain the invertebrates.
Under contract with the Service, Veni (2002) re-evaluated and, where applicable, redrew the boundaries of each karst zone originally delineated in Veni (1994). Revisions were based on current geologic mapping, further studies of cave and karst development, and the most current information available on the distribution of listed and nonlisted cave-adapted species (Veni 2002).
Endangered Karst Invertebrate Distribution
As of December 2002, 475 caves were known to occur in Bexar County, some of which have been biologically surveyed for listed species (Veni 2002). At least 97 of the 475 caves were sealed or destroyed before they could be biologically surveyed (Veni 2002). Not all of the remaining caves in Bexar County have been adequately surveyed for invertebrates. It is likely that some of these caves will be found to contain one or more of the listed species. When the species were listed as endangered in December 2000, the Service knew of 57 occupied caves. When critical habitat was proposed in Bexar County in August 2002, we knew of 69 occupied caves. We now know of 74 caves containing one or more of the listed species in Bexar County (Table 1). The following species status descriptions are based on information available to us as of December 23, 2002.
Braken Bat Cave Meshweaver
The Braken Bat Cave meshweaver,
Cicurina venii
(Araneae: Dictynidae), was first collected on November 22, 1980, by G. Veni and described by Gertsch (1992). Braken Bat Cave remains the only location known to contain this species (Table 1).
Cokendolpher Cave Harvestman
The Cokendolpher cave harvestman,
Texella cokendolpheri
(Opilionida: Phalangodidae), was collected in 1982 and described by Ubick and Briggs (1992). This species, along with the Robber Baron Cave meshweaver, is only known from Robber Baron Cave (Table 1).
Government Canyon Bat Cave Meshweaver
The Government Canyon Bat Cave meshweaver,
Cicurina vespera
(Araneae: Dictynidae), was first collected on August 11, 1965, by J. Reddell and J. Fish (Reddell 1993), and described by Gertsch (1992). The species is currently known from Government Canyon Bat Cave in Government Canyon State Natural Area and an unnamed cave referred to as “5 miles northeast of Helotes.” However, the specimen collected from the latter cave has been tentatively identified as a new species (Cokendolpher, in press).
Government Canyon Bat Cave Spider
The Government Canyon Bat Cave spider,
Neoleptoneta microps
(Araneae: Leptonetidae), was first collected on August 11, 1965, by J. Reddell and J. Fish (Reddell 1993). The species was originally described by Gertsch (1974)
as
Leptoneta microps
and later reassigned to
Neoleptoneta
following Brignoli (1977) and Platnick (1986). The species is known from 2 caves in Government Canyon State Natural Area (Table 1).
Madla Cave Meshweaver
The Madla Cave meshweaver,
Cicurina madla
(Araneae: Dictynidae), was first collected on October 4, 1963, by J. Reddell and D. McKenzie (Reddell 1993) and described by Gertsch (1992). The Madla Cave meshweaver has been found in eight caves (Table 1).
The Service is aware of 11 additional caves from which immature, eyeless troglobitic
Cicurina
spiders have been collected (SWCA 2000). Eight of these are in caves that have other listed species and are either included in critical habitat areas or areas that are not included in the designation due to the provision of adequate special management. The remaining three are in caves where authorization for take of
C. madla
was granted to La Cantera under a section 10(a)(1)(B) permit. These three caves have been, or will be, heavily impacted and are, therefore, not expected to contribute to the species recovery.
Robber Baron Cave Meshweaver
The Robber Baron Cave meshweaver,
Cicurina baronia
(Araneae: Dictynidae), was first collected in Robber Baron Cave February 28, 1969, by R. Bartholomew (Reddell 1993) and described by Gertsch (1992). The Robber Baron Cave meshweaver (a spider) is only known from Robber Baron Cave (Table 1).
Beetle (No Common Name)
Rhadine exilis
The beetle
Rhadine exilis
(Coleoptera: Carabidae) was first collected in 1959. The species was described by Barr and Lawrence (1960) as
Agonum exile
and later assigned to the genus
Rhadine
(Barr 1974). The species is currently known to have been found in 47 caves (Table 1).
Beetle (No Common Name)
Rhadine infernalis
Rhadine infernalis
(Coleoptera: Carabidae) was first collected in 1959. The species was initially described by Barr and Lawrence (1960) as
Agonum infernale,
but later assigned to the genus
Rhadine
(Barr 1974). Scientists have recognized three subspecies (
Rhadine infernalis ewersi, Rhadine infernalis infernalis, Rhadine infernalis
new subspecies) (Barr 1974; Barr and Lawrence 1960; Reddell 1998), all of which are included as protected under the Federal listing of the full species as endangered. A total of 35 caves are known to contain
Rhadine infernalis
(Table 1).
Rhadine infernalis ewersi
is known from 3 caves.
Rhadine infernalis infernalis
is known from 19 caves. The unnamed new subspecies (
Rhadine infernalis
new subspecies) was known from 6 caves at the time of the proposed rule designating critical habitat. During the public comment period, we received confirmation that
R. infernalis
collected from Obvious Little Cave has been identified as
R. infernalis
new subspecies. An additional 5 caves were identified in the proposed rule as containing
Rhadine infernalis
that have not yet been identified at the subspecies level. During the public comment period, we received survey information confirming the presence of
R. infernalis
in Continental Cave (Table 1). According to Veni (2002), specimens from these caves are probably
R. infernalis infernalis,
but have either not yet been fully identified or not reported.
Helotes Mold Beetle
The Helotes mold beetle,
Batrisodes venyivi
(Coleoptera: Pselaphidae), was first collected in 1984 and described by Chandler (1992). The species is currently known from six caves (Table 1). The location of one of the caves, referred to as “unnamed cave
1/2
mile north of Helotes,” is unknown. The original record for this cave is from Barr's (1974) description of
Rhadine exilis.
Because the number of caves in the general area is large, the location of this cave cannot be positively identified (George Veni, George Veni & Associates, pers. comm. 2002). However, this cave may not be a separate location after all, but may be an existing cave listed by the collector under the alternative name “5 miles NE of Helotes.” The cave referred to as “5 miles NE of Helotes,” also has an unknown location.
Table 1.—Caves Known as of December 23, 2002, To Contain One or More of the Nine Bexar County, Texas, Karst Invertebrates Federally Listed as Endangered
Species (# of caves)
Cave name
Braken Bat Cave meshweaver (
C. venii
) (1)
Braken Bat Cave.
Cokendolpher cave harvestman (
Texella cokendolpheri
) (1)
Robber Baron Cave.
Government Canyon Bat Cave meshweaver (
C. vespera
) (1)
Government Canyon Bat Cave.
Government Canyon Bat Cave spider (
Neoleptoneta microps
) (2)
Government Canyon Bat Cave, Surprise Sink.
Madla Cave meshweaver (
Cicurina madla
) (8)
Christmas Cave, Madla's Cave, Madla's Drop Cave, Helotes Blowhole, Headquarters Cave, Hills and Dales Pit, Robber's Cave, Lost Pothole.
Robber Baron Cave meshweaver (
C. baronia
) (1)
Robber Baron Cave
Beetle (no common name) (
Rhadine exilis
) (47)
40 mm Cave, B-52 Cave, Backhole, Black Cat Cave, Boneyard Pit, Bunny Hole, Cross the Creek Cave, Dos Viboras Cave, Eagles 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, 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 Blowhole, Helotes Hilltop Cave, Logan's Cave, unnamed cave
1/2
mile N. of Helotes.
Creek Bank Cave, Government Canyon Bat Cave, Lithic Ridge Cave, Pig Cave, San Antonio Ranch Pit, Tight Cave.
Hills and Dales Pit, 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.
Beetle (no common name)
R. infernalis
(6) (subspecies not indicated—probably
R. infernalis infernalis
but individual specimens are either not fully identified or reported (Veni 2002))
Canyon Ranch Pit, Continental Cave, Fat Man's Nightmare Cave, Pig Cave, San Antonio Ranch Pit, Scenic Overlook Cave.
R. infernalis ewersi
(3)
Flying Buzzworm Cave, Headquarters Cave, Low Priority Cave.
R. infernalis
new subspecies (7)
Caracol Creek Coon Cave, Game Pasture Cave No. 1, Isopit, King Toad Cave, Obvious Little Cave, Stevens Ranch Trash Hole Cave, Wurzbach Bat Cave.
R. infernalis infernalis
(19)
Bone Pile Cave, Dancing Rattler Cave, Government Canyon Bat Cave, Hackberry Sink, Lithic Ridge Cave, Surprise Sink, Christmas Cave, Helotes Blowhole, Logan's Cave, Madla's Cave, Madla's Drop Cave, Crownridge Canyon Cave, Genesis Cave, John Wagner Ranch Cave No. 3, Kamikazi Cricket Cave, Mattke Cave, Robber's Cave, Scorpion Cave, Three Fingers Cave.
Helotes mold beetle (
Batrisodes venyivi
) (6)
San Antonio Ranch Pit, Scenic Overlook Cave, Christmas Cave, unnamed cave
1/2
mile N of Helotes, Helotes Hilltop Cave, unnamed cave 5 miles NE of Helotes.
Animal Community
Cave Crickets
Cave crickets are a critical source of nutrient input for karst ecosystems (Barr 1968; Reddell 1993). Cave crickets in the genus
Ceuthophilus
occur in most caves in Texas (Reddell 1966). Being sensitive to temperature extremes and drying, cave crickets forage on the surface at night and roost in the cave during the day. Cave crickets lay their eggs in the cave, providing food for a variety of karst species (Mitchell 1971b). Some karst species also feed on cave cricket feces (Barr 1968; Poulson
et al.
1995) and on adults and nymphs directly (Cokendolpher, in press; Elliott 1994a). Cave crickets are scavengers or detritivores, feeding on dead insects, carrion, and some fruits, but not on foliage (Elliott 1994a).
Elliott (2000) studied the community ecology of three caves in protected areas of varying size in northwest Travis and Williamson Counties, Texas, from 1993 to 1999. The three caves are in areas protected as mitigation for two listed species found in Lakeline Cave during the development of Lakeline Mall. Lakeline Cave is located on a 0.9 hectares (ha) (2.3 acres (ac)) protected area and is surrounded by parking lots and a shopping center. Temples of Thor Cave and Testudo Tube are within much larger tracts of undeveloped land, being located on 42.5 ha (105 ac), and 10.5 ha (26 ac) of protected areas, respectively. During the monitoring study (1993-1999), the number of cave crickets drastically declined in Lakeline Cave, while they increased slightly or decreased moderately in the other two caves. Elliott (2000) concluded that drought, fire ants, and a decrease in racoon visitation caused the decline of the cave crickets. These results are consistent with reports of declines and extinctions of several invertebrates and small mammals (resulting from lower survivorship, higher emigration, and/or lower immigration) from habitat patches ranging in size from 2 to 7 ha (5 to 17 ac) (Mader 1984; Tscharntke 1992; Keith
et al.
1993; Lindenmayer and Possingham 1995; Hill
et al.
1996).
Elliott (1994a) evaluated cave cricket foraging within 50 m (164 ft) of cave entrances at his study sites and found crickets to the end of the 50 m sampling distance. On a few occasions he observed cave crickets beyond his sampling sites, and on one occasion he set a trap 60 m (197 ft) from the entrance and found one large adult. Elliott (1994a) concluded that the “largest adults probably are capable of traveling far beyond 60 m from the entrance,” but he did not have the data necessary to establish how far they go. During recent cave cricket surveys conducted for an ongoing project in central Texas, an adult cave cricket was found foraging 95 m (311 ft) from the study cave (Steve Taylor, Illinois Natural History Survey, pers. comm. 2002).
As trogloxenes, cave cricket populations are dependent on the patchy distribution of karst voids. Therefore, cave cricket populations may have a metapopulation (subpopulations that interact via the dispersal of individuals from one subpopulation to others) or a source-sink population structure, and it may be important to protect multiple karst features that support cave crickets in a karst ecosystem (Helf
et al.
1995). Metapopulation dynamics require movement among patches, and persistence requires interacting patches that undergo local extinctions and establishment of new subpopulations in areas previously devoid of individuals (Hanski 1999). “Source” populations are those that occur “in a high-quality habitat in which birth rate generally exceeds the death rate and the excess individuals leave as emigrants.” “Sink” populations are those that occur “in a low-quality habitat in which the birth rate is generally lower than the death rate and population density is maintained by immigrants from source populations (Meffe
et al.
1997). Because cave crickets are a key source of nutrient input for karst ecosystems, conserving adequate areas between karst patches in a manner that allows for movement of individuals among cave cricket populations is likely an important factor in long-term maintenance for karst ecosystems.
Subsurface karst areas may also be important to allow movement among cave cricket populations through the subsurface environment associated with continuous limestone blocks. For example, Caccone and Sbordoni (1987) studied nine species of North American cave crickets (genera
Eukadenoecus
and
Hadenoecus
) from sites in North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia, Kentucky, and Alabama. Seven of the species were obligate cave-dwelling species that emerged at night to feed. Through genetic analyses of the cave-dwelling species, they found that species or groups of populations inhabiting areas where the limestone is continuous and highly fissured are genetically less differentiated than are populations occurring in regions where the limestone distribution is more fragmented, indicating more exchange of individuals in areas of continuous karst.
Helf
et al.
(1995) suggested that populations of an eastern species of cave cricket (
Hadenoecus subterraneus
) may be at risk because they do not recover quickly after events such as drought, floods, and temperature extremes that preclude or diminish foraging opportunities. These cave cricket populations may have source-sink population dynamics, with some
karst features acting as sources and the majority of karst features acting as sinks, but Helf
et al.
(1995) recommends that “even sink populations should be protected because their emigrants can “rescue” source populations that experience local decimation.” These studies suggest that it is important to protect the geological features that connect caves and maintain habitat corridors among caves.
Other Surface Animals
Many central Texas caves with endangered invertebrate species are frequented by mammals and several species of reptiles and amphibians (Reddell 1967). Although there are no studies establishing 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. An important source of nutrients for the cave species may be the fungus, microbes, and/or other troglophiles and troglobites that grow or feed on feces (Elliott 1994b; Gounot 1994).
For predatory troglobites (such as the listed Bexar County invertebrates), invertebrates that accidently occur in the caves may also be an important nutrient source (Hopper 2000). 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; 1966; 1999).
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 possibly, (3) roots that extend into subsurface areas. Surface vegetation also acts as a buffer for the subsurface environment against drastic changes in the temperature and moisture regime and serves to filter pollutants before they enter the karst system (Biological Advisory Team 1990; Veni 1988). In some cases, healthy native plant communities also help control certain exotic species (such as fire ants) (Porter
et al.
1988) that may compete with or prey upon the listed species and other species (such as cave crickets) that are important nutrient contributors (Elliott 1994a; Helf,
in litt.
2002).
Tree roots have been found to provide a major energy source in shallow lava tubes and limestone caves in Hawaii (Howarth 1981). Jackson
et al.
(1999) investigated rooting depth in 21 caves on the Edwards Plateau to assess the belowground vegetational community structure and the functional importance of roots. They observed roots penetrating up to 25 m (82 ft) into the interior of 20 of the caves, with roots of 6 tree species common to the plateau penetrating to below 5 m (16.4 ft).
Along with providing directly and indirectly nutrients to the karst ecosystem, a healthy vegetative community may also help control the spread of exotic species. The red imported fire ant (
Solenopsis invicta
) 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; Porter and Savignano 1990) and is a threat to the karst invertebrates (Elliott 1994b; USFWS 1994). 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 listed karst invertebrates are especially vulnerable to invasion by fire ants and other exotic species. In addition to preying on cave invertebrate species, including cave crickets, fire ants may compete with cave crickets for food (Elliott 1994a; Helf
in litt.
2002). Helf (
in litt.
2002) states that competition for food between fire ants and cave crickets (
Ceuthophilus secretus
) may be a more important interaction than predation. 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.
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). Porter
et al.
(1991) state that control of fire ants in areas greater than 5 ha (12 ac) may be more effective than in smaller areas since 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; 1991).
Listed species, and their associated prey items, have adapted to native vegetation, with its associated nutrients, surface foliage, and subsurface roots. Before 1860, Bexar County native vegetation consisted of an approximate equal mix of areas with woody and grassland plants (Del Weniger 1988). In more recent times, exotic species have often replaced native plants. The effects on listed invertebrates of replacement of native with exotic vegetation have not been reported.
Woodland-Grassland Community
Because of the various roles played by surface vegetation in maintaining the cave and karst ecosystem, including the listed karst 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) 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), genetic variation (Bazzaz 1983; Menges 1995; Young 1995), and pollination (Groom 1998; Jennersten 1995; Bigger 1999). Pavlik (1996) stated that long-lived, self-fertilizing, woody plants with high fecundity would be expected to have minimum viable population sizes in the range of 50-250 reproductive individuals. Fifty reproductive individuals is a reasonable minimum figure for one of the dominant species of the community (
Juniperous ashei
) based on reproductive profiles (Van Auken
et al.
1979; Van Auken
et al.
1980; Van Auken
et al.
1981). This figure would likely be an underestimate for other woody species present in central Texas woodlands, however, because these other 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 these species may require population sizes at
the higher end of range (that is, nearer 250 individuals) suggested by Pavlik (1996) to be viable, 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.
On the basis of an analysis of recorded densities, corrected for nonreproductive 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). Based on our calculations, the four highest area requirements to maintain at least 80 mature individuals were for species that occur at lower densities. These included 80 ha (198 ac) for
Condalia hookeri,
and approximately 32 ha (79 ac) for each of
Ptelea trifoliata,
Ungnadia speciosa,
and
Bumelia lanuginosa.
Our calculations indicate that the area needed to maintain the 7 species with the highest average dominance values (
Juniperus ashei,
Quercus fusiformis,
Quercus texana,
Acacia greggii,
Rhus virens,
Berberis trifoliata,
and
Ulmus crassifolia
) is approximately 13 ha (33 ac). This number would maintain 80 reproductive individuals for 15 of the 24 species. Nine of the species are rarer in the community and all have importance values of less than 1.0. The area needed to maintain these nine species ranges from approximately 20 to 80 ha (49 to 198 ac), with 7 of them in the 26 ha to 32 ha (65 to 79 ac) range.
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, 1971) examined species on an 8-acre tract over time, with 123 species, but a 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. Robertson
et al.
(1997), in a slightly more mesic grassland habitat, found that a 4 ha (10 ac) site captured most of the species diversity (100 species) present even in much larger patches, although it does not address population sizes and persistence in isolation, and an increase to a 6 ha (14 ac) tract increased species representation to 140. One paper on a grassland in a more westerly and drier location in Central Texas recorded 157 taxa in a 16 ha (40 ac) exclosure studied between 1948 and the mid-1970's (Smeins and Merrill 1976).
Primary recruitment of new individuals of grass species in grasslands is from seedling establishment. Many grass species use wind to disperse their seeds and dispersal distances may be small. The process of expansion through rhizomes (underground stems) is slow and clonal, which reduces genetic variability. Seed dispersal, soil texture, and suitable soil moisture profiles at critical times are important factors for maintaining viability (Coffin
et al.
1993).
As described above, we have reviewed the available information concerning grasslands and grassland species in Central Texas. The information is of a relatively general nature, and we did not find specific information addressing the role that grasslands or grass species might play in contributing, directly or indirectly, to karst ecosystems. While grassland communities and species may be important to maintaining the karst community, we lack adequate information to credibly estimate surface habitat patch size requirements for grass species in relation to karst ecosystems.
The presence of surface vegetation communities is important for maintaining the humid conditions, stable temperatures, and natural airflow in cave and karst environments. Vegetation also plays an important role in water quality. Since soil depth is shallow over the limestone plateau, water collects as sheet flow on the surface following rain and enters the subsurface environment through cave openings, fractures, and solutionally-enlarged bedding planes. This direct, rapid transport of water through the karst allows for little or no purification (Veni 1988), allowing contaminants and sediments to enter directly into the subsurface environment. As a result, karst features and karst dependent invertebrates are vulnerable to the adverse effects of pollution from contaminated ground and surface water. Maintaining stable environmental conditions and protecting groundwater quality and quantity requires managing a healthy vegetation community to avoid threats from surface and subsurface drainage to the karst environment needed by the karst dependent species. This includes not only the cave entrances accessible to humans, but also sinks, depressions, fractures, and fissures, which may serve as subsurface conduits into caves and other subsurface spaces used by the invertebrates.
Buffer Areas
To maintain a viable vegetative community, including woodland and grassland species, a buffer area is needed to shield the core habitat from impacts associated with edge effects or disturbance from adjacent urban development (Lovejoy
et al.
1986; Yahner 1988). In this context, edge effects refer to the adverse changes to natural communities (primarily from increases in invasive species and pollutants, and changes in microclimates) from nearby areas that have been modified for human development.
The changes caused by edge effects can occur rapidly. For example, vegetation 2 m (6.6 ft) from a newly created edge can be altered within days (Lovejoy
et al.
1986). Edges may allow invasive plant species to gain a foothold where the native vegetation had previously prevented their spread (Saunders
et al.
1990; Kotanen
et al.
1998; Suarez
et al.
1998; Meiners and Steward 1999). 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; Harris 1984; Mader 1984; Thompson 1985; Lovejoy
et al.
1986; Yahner 1988; Fajer
et al.
1989; Kindvall 1992; Tscharntke 1992; Keith
et al.
1993; Hanski 1995; Lindenmayer and Possingham 1995; Bowers
et al.
1996; Hill
et al.
1996; Kozlov 1996; Kuussaari
et al.
1996; Turner 1996; Mankin and Warner 1997; Burke and Nol 1998; Didham 1998; Suarez
et al.
1998; Crist and Ahern 1999; Kindvall 1999). Changes in plant and animal species composition as a result of edge effects may unnaturally change the nutrient cycling processes required to support cave and karst ecosystem dynamics. To minimize edge effects, the core area must have a sufficient buffer area.
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) for estimating the width of the buffer area needed. We used this general rule to estimate the width of buffer areas needed to protect the habitat core areas. The average height of native mature trees in the Edwards woodland association in Texas ranges from 3 to 9
m (10 to 30 ft) (Van Auken
et al.
1979). Applying the “three tree height” general rule, and using the average value of 6.6 m for tree height, we estimated that a buffer width of at least 20 m (66 ft) is needed around a core habitat area to protect the vegetative community from edge effects. Based on this rule, 7 acres is necessary to protect a 33-acre core area. We recognize that the “three tree height” approach described by Harris (1984) 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. Since the effects of edge on woodland/grass land mosaic communities have not been well studied, the “three tree height” recommendation is considered to be the best available peer-reviewed science to protect woodland areas from edge effects (Dr. Kathryn Kennedy, Center for Plant Conservation, pers. comm. 2003). The Texas Parks and Wildlife Department is also in general agreement about the need for some type of buffer as a means of addressing edge effects, but currently has not specific recommendations on appropriate size for such a buffer ( John Herron, Texas Parks and Wildlife Department, pers. comm. 2003).
Animal communities also should be buffered 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; Hansson 1998). Invertebrate species are affected by edges. Mader
et al.
(1990) found that carabid beetles and lycosid spiders avoided crossing unpaved roads that were even smaller than 3 m (9 ft) wide. Saunders
et al.
(1990) suggested that as little as 100 m (328 ft) 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 50 to 100 m (164 to 328 ft) or greater to ameliorate edge effects (Lovejoy
et al.
1986; Wilcove
et al.
1986; Laurance 1991; Laurance and Yensen 1991; Kapos
et al.
1993; Andren 1995; Reed
et al.
1996; Burke and Nol 1998; Didham 1998; Suarez
et al.
1998).
Nonnative fire ants are known to be harmful to many species of invertebrates and vertebrates. In coastal southern California, Suarez
et al.
(1998) 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 200 m (656 ft) (Suarez
et al.
1998).
Information on the area needed to maintain populations of animal species, including cave crickets, found in Central Texas is lacking. As discussed above, animal communities should be buffered by areas of 50 to 100 m (164 to 328 ft) or greater to ameliorate edge effects, and by areas of 200 m (656 ft) to buffer against the effects of fire ants. From this data, we determined that a buffer of 100 m (328 ft), in addition to the 50 m (164 ft) cave cricket foraging area, would, at a minimum, protect the cave cricket foraging area from the effects of edge and nonnative species invasions.
Fragmentation
Haskell (2000) examined the effect of habitat fragmentation by unpaved roads through otherwise contiguous forest in the southern Appalachian Mountains and found reduced soil macroinvertebrate species abundance up to 100 m (328 ft) from the road and declines in faunal richness up to 15 m (50 ft) from the road. Haskell (2000) pointed out that “these changes may have additional consequences for the functioning of the forest ecosystem and the biological diversity found within this system. The macroinvertebrate fauna of the leaf litter plays a pivotal role in the ability of the soil to process energy and nutrients.” Haskell further points out that these changes may in turn affect the distribution and abundance of other organisms, particularly plants. Changes in abundance in litter dwelling macroinvertebrates may also affect ground-foraging vertebrate fauna (Haskell 2000).
Invertebrate biomass per unit area has been found to be less in small fragmented habitats, which may result in reduced food available for cave crickets. Burke and Nol (1998), working in southern Ontario, Canada, found a greater biomass of leaf litter invertebrates in large (≥20 ha (49 ac)) than in smaller forested areas. Zanette
et al.
(2000) in New South Wales, Australia, reported that the biomass of ground dwelling invertebrates was 1.6 times greater in large (> 400 ha (988 ac)) than in smaller (~55 ha (136 ac)) forested areas.
Dispersal
The ability of individuals to move between preferred habitat patches is essential for colonization and population viability (Eber and Brandl 1996; Fahrig and Merriam 1994; Hill
et al.
1996; Kattan
et al.
1994; Kindvall 1999; Kozlov 1996; Kuussaari
et al.
1996; Turner 1996). 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; Kindvall 1999; Kuussaari
et al.
1996; Tiebout and Anderson 1997). 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).
It is likely that many cave systems are connected throughout the subsurface geologic formation even though this may not be readily apparent from surface observations. The extent to which listed species use interstitial spaces and passages is not known. Troglobitic species may retreat into these small interstitial spaces where the physical environment is more stable (Howarth 1983) and may spend the majority of their time in such retreats, only leaving them during temporary forays into the larger cave passages to forage (Howarth 1987). During several karst invertebrate surveys conducted in Bexar County caves, Service biologists have observed that troglobites, including listed species, were not found when temperature and humidity in the cave was low. Upon returning to the same cave once environmental conditions returned to optimal, the listed species and other troglobites were observed.
Small voids (inaccessible to humans) and interstitial spaces can also provide subsurface corridors for movement of listed species and cave crickets between and among caves and karst features. Cores drilled around and between occupied caves have led to discovery of additional void space that was hydrologically, but not physically connected to the humanly-accessible portion of an occupied cave. Listed species were found in this void space.
Summary
The conservation of the endangered karst invertebrates depends on a self-sustaining karst ecosystem; surface and subsurface drainage basins to maintain adequate levels 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 core area buffered from the impacts associated with fragmentation, isolation, edge effects, and other factors that may threaten ecosystem stability. Depending on the size and shape of these core habitat areas or patches, in order to remain viable, they may also require connections to other habitat patches.
Previous Federal Action
On January 16, 1992, we received a petition submitted by representatives of the Helotes Creek Association, the Balcones Canyonlands Conservation Coalition, the Texas Speleological Association, the Alamo Group of the Sierra Club, and the Texas Cave Management Association to add the nine invertebrates to the List of Threatened and Endangered Wildlife. On December 1, 1993, we announced in the
Federal Register
(58 FR 63328) a 90-day finding that the petition presented substantial information that listing may be warranted.
On November 15, 1994, we added eight of the nine invertebrates to the Animal Notice of Review as category 2 candidate species in the
Federal Register
(59 FR 58982). We intended to include
Rhadine exilis
in the notice of review, but an oversight occurred and it did not appear in the published notice. Category 2 candidates, a classification since discontinued, were those taxa for which we had data indicating that listing was possibly appropriate, but for which we lacked substantial data on biological vulnerability and threats to support proposed listing rules.
On December 30, 1998, we published a proposed rule to list the nine Bexar County karst invertebrates as endangered (63 FR 71855). Incorporating comments and new information received during the public comment period on the proposed rule, we published a final rule to list the nine Bexar County karst invertebrate species as endangered in the
Federal Register
on December 26, 2000 (65 FR 81419).
In the proposed rule for listing these species, we indicated that designation of critical habitat was not prudent for the nine invertebrates because the publication of precise species locations and maps and descriptions of critical habitat in the
Federal Register
would make the nine species more vulnerable to incidents of vandalism through increased recreational visits to their cave habitat and through purposeful destruction of the caves. We also indicated that designation of critical habitat was not prudent because it would not provide any additional benefits beyond those provided through listing the species as endangered.
Based on recent court decisions (for example,
Natural Resources Defense Council
v.
U.S. Department of the Interior
113 F. 3d 1121 (9th Cir. 1997);
Conservation Council for Hawaii
v.
Babbitt,
2 F. Supp. 2d 1280 (D. Hawaii 1998)) and the standards applied in those judicial opinions, we reexamined the question of whether critical habitat for the nine invertebrates would be prudent. After reexamining the available evidence for the nine invertebrates, we did not find specific evidence of collection or trade of these or any similarly situated species. Consequently, in our final rule listing the species, we found that “by designating critical habitat in a manner that does not identify specific cave locations, the threat of vandalism by recreational visits to the cave or purposeful destruction by unknown parties should not be increased” (65 FR 81419). Therefore, our final rule to list the species as endangered also included our determination that critical habitat designation was prudent as we did not find specific evidence of increased vandalism, and we found there may be some educational or informational benefit to designating critical habitat. Thus, we found that the benefits of designating critical habitat for the nine karst invertebrate species outweighed the benefits of not designating critical habitat.
The Final Listing Priority Guidance for FY 2000 (64 FR 57114) stated that we would undertake critical habitat determinations and designations during FY 2000 as allowed by our funding allocation for that year. As explained in detail in the Listing Priority Guidance, our listing budget was insufficient to allow us to immediately complete all of the listing actions required by the Act during FY 2000. We stated that we would propose designation of critical habitat in the future at such time when our available resources and priorities allowed.
On November 1, 2000, the Center for Biological Diversity (Center) filed a complaint against the Service alleging that the Service exceeded its 1-year deadline to publish a final rule to list and to designate critical habitat for the nine Bexar County cave invertebrates. Subsequent to the Service publishing the final rule to list these nine species as endangered on December 26, 2000, the Center agreed to dismiss its claim regarding the listing of the species. Under the terms of a settlement reached between the Center and the Service, the Service agreed to submit to the
Federal Register
for publication a proposed critical habitat determination on or by June 30, 2002, and a final determination on or by January 25, 2003. Sixty-day extensions on the deadlines to submit both the proposed and final critical habitat determinations to the
Federal Register
for publication were approved by the court, and the new deadlines became August 31, 2002, and March 26, 2003, for the proposed and final rules, respectively.
On February 28, 2002, we mailed letters to the Texas Parks and Wildlife Department and the Texas Natural Resource Conservation Commission informing them that we were in the process of designating critical habitat for the nine Bexar County karst invertebrates. We requested any additional available information on the listed species, including biology; life history; habitat requirements; distribution, including geologic controls to species distribution; current threats; and management activities, current or in the foreseeable future. The letters contained a current list of Bexar County caves known to contain listed species, a map showing the general distribution of these species within each Karst Fauna Region, and a list of the references pertaining to these species and their distribution as we know it. We requested their review and comments on our current information and asked their assistance in providing any additional available information.
We also mailed approximately 300 pre-proposal letters to interested parties and cave biologists on March 20, 2002, informing them that we were in the process of designating critical habitat for the 9 listed karst invertebrates. The letters contained a copy of the final rule to list these Bexar County invertebrate species as endangered, a map showing the general distribution of these species, a list of literature about these species and their habitats, and a brief summary with questions and answers on critical habitat. We requested comments on: (1) The reasons why any habitat should or should not be determined to be critical habitat as provided by section 4 of the Act, including whether the benefits of excluding areas will outweigh the benefits of including areas; (2) land use practices and current or planned activities in the subject areas and their possible impacts on possible critical habitat; (3) any foreseeable economic or other impacts resulting from the proposed designation of critical habitat, and particularly any impacts on small entities or families; and (4) economic and other benefits associated with designating critical habitat for the Bexar County karst invertebrates.
On August 27, 2002, we proposed that 25 units encompassing a total of approximately 3,857 ha (9,516 ac) in
Bexar County, Texas, be designated as critical habitat for the nine karst invertebrates (67 FR 55064). The comment period for the proposed rule was originally scheduled to close on November 25, 2002, but was extended until December 23, 2002 (67 FR 70203), to allow for a 30-day comment period on the draft economic analysis. Thus, we accepted comments on the proposed rule and the economic analysis until December 23, 2002.
Summary of Comments and Recommendations
In the August 27, 2002, proposed rule, we requested all interested parties to submit comments or information concerning the designation of critical habitat for the nine endangered Bexar County invertebrates (67 FR 55064). During the comment period, we held a public hearing in San Antonio on October 30, 2002. We published a newspaper notice inviting public comment and announcing the public hearing in the San Antonio Express-News. A transcript of the hearing is available for inspection (
see
ADDRESSES
section). The comment period was originally scheduled to close on November 25, 2002.
On November 21, 2002, we announced the availability of the draft economic analysis and requested comments on it and the proposal during an extension of the comment period until December 23, 2002 (67 FR 70203). We contacted all appropriate State and Federal agencies, county governments, scientific organizations, and other interested parties and invited them to comment. We also provided notification of these documents through email, telephone calls, letters, and news releases faxed and/or mailed to affected elected officials, media outlets, local jurisdictions, and interest groups. For the notice of the proposed rule, we mailed over 1,500 letters to interested parties. Later we sent over 1,200 post cards notifying interested parties of the availability of the draft economic analysis and the extension of the comment period. The number of parties on the mailing list fell as we deleted out-of-date and duplicate addresses. We also published all of the associated documents on the Service's regional Internet site following their release.
We solicited 11 independent experts who are familiar with these species and the karst ecosystem to peer-review the proposed critical habitat designation. Only one of the peer reviewers submitted comments, generally in support of the proposed designation (see “Peer Review” section below). We also received a total of 42 written comments, and 3 oral comments at the public hearing. Of those comments indicating a preference, 10 supported the critical habitat designation and 13 indicated opposition to designation. Many commenters did not express opposition to the designation, but did express opposition to specific areas being included. We reviewed all comments received for substantive issues and new data regarding critical habitat and the draft economic analysis. Here, we address all comments on both documents received during the comment periods, as well as public hearing testimony. We have grouped similar comments and addressed them in the following summary.
Issue 1: Biological Justification and Methodology for Size of Critical Habitat Units
(1)
Comment:
The Service should designate smaller areas for critical habitat units, including: (1) Surface and subsurface drainage areas; (2) cave cricket foraging areas; and (3) dominant and subdominant woody species, rather than uncommon plant species. The Service focused its methodology on surface plant communities, but little information exists relating particular vegetation communities to the subsurface habitat of the listed species.
Our Response:
We believe it is well documented that surface flora and fauna communities are an essential energy source for fauna, including the nine endangered invertebrates, in the karst environment. The areas needed to support dominant, subdominant, and “other woody species” common to the Edwards Plateau were included in our proposal to incorporate key components of the native vegetative community that contribute directly to nutrient input, and which also support the animal community that is another source of nutrient input to karst areas. We do not have data from vegetation surveys conducted around occupied caves to determine the importance of rarer plant species. Therefore, in this final designation we have reduced the size of all of the critical habitat units based on the amount of area that we believe, based on the best available information, is needed to support at least 15 of 24 species of vegetation on the Edwards Plateau, including the seven species with the highest dominance values, but not the rarer plant species (see “Criteria Used to Delineate Critical Habitat” section below for further explanation).
(2)
Comment:
The Service should designate larger areas for the critical habitat units to: (1) Include all or most of Karst Zone 1; (2) all or portions of Karst Zone 2; (3) reduce fragmentation of habitat; (4) consider subsurface karst voids between known caves that may provide habitat for the species; (5) provide better protection against pollution; and (6) provide dispersal corridors for cave crickets.
Our Response:
We agree that it is likely that all of these concerns have the potential to affect the conservation of the endangered karst invertebrates. Much of the biology and ecology of these karst-adapted listed species is not well understood. Critical habitat was delineated to encompass areas on which are found those components of the karst ecosystem for which sufficient information exists to determine that they are essential to the conservation of the listed species.
We recognize that areas outside of the boundaries of critical habitat may be important for the karst invertebrates for purposes such as providing habitat in interstitial karst voids (beyond the known caves), additional sources of nutrients, or dispersal corridors. However, we did not have sufficient data when we proposed critical habitat, nor were any data provided during the comment period, that would allow us to adequately assess the importance to occupied caves of other areas of Karst Zones 1 or 2, karst voids between known caves, larger buffers, or areas that are needed for dispersal corridors for cave crickets. For instance, members of the Technical Subcommittee of the Karst Invertebrate Recovery Team, who are experts on the species and the karst ecosystems, agree that it is likely the invertebrates spend considerable time, perhaps the majority of time, in the human-inaccessible karst voids (interstitial spaces) associated with the cave (Steve Taylor, Technical Subcommittee chair, pers. comm. 2002). However, the distance that these invertebrates go from the cave into the surrounding karst is unknown. Since protection of the surface and subsurface drainage areas associated with each occupied cave is important to buffer the cave from pollutants, these drainage areas were included, where possible, in the critical habitat designation. Additional scientific discovery may show that larger areas are needed for long-term conservation, and we will continue to incorporate such information into planning and implementing various conservation activities for these species. Given the best available information, we believe the specific areas designated in this rule contain one or more of the physical or biological features that are essential to the conservation of the species and meet the definition of critical habitat as provided in section 3 of the Act.
(3)
Comment:
The proposed rule did not show that designating critical habitat was essential to conservation of the species or requires special management.
Our Response:
Section 3 of the Act defines critical habitat as “(i) the specific areas within the geographical area occupied by the species, at the time it is listed * * *, on which are found those physical or biological features (I) essential to the conservation of the species and (II) which may require special management considerations or protection; and (ii) specific areas outside the geographical area occupied by the species * * * upon a determination * * * that such areas are essential for the conservation of the species.” Regulations (50 CFR 424.12) direct us to “focus on the principal biological or physical constituent elements within the defined area that are essential to the conservation of the species.” Conservation is defined in the Act, section 3, as “the use of all methods and procedures which are necessary to bring any endangered species or threatened species to the point at which the measures provided pursuant to this Act are no longer necessary.” We believe the proposed rule demonstrated that the primary constituent elements we recognized are essential to the conservation of the species. The areas we are designating all contain one or more of such features.
The caves and the associated karst are essential to the conservation of the species because the invertebrates live, feed, and reproduce in the caves and the associated karst structures. The subsurface drainage area is essential to provide the environmental conditions in the cave that are requirements for the species. The surface drainage area helps maintain the environmental conditions and helps maintain an energy flow into the underground karst system. The surface vegetation is a direct source of energy through plant materials entering the karst system, and the surface vegetation also supports animals (such as cave crickets) that process the plant materials and then leave the resulting nutrients in the cave. Cave crickets are likely one of the most important sources of nutrients that support the endangered karst invertebrates. We believe this final rule documents that the areas designated meet the definition of critical habitat in that they contain one or more of the physical and biological features that are essential to the conservation of the endangered karst invertebrates. We also have carefully reviewed whether such areas may require special management considerations or protection, as called for under the definition of critical habitat in section 3(5)A)(i) of the Act. On the basis of our evaluation of certain areas already covered by conservation plans and thus already have special management considerations or protection, we did not include some areas in this final designation. (
See
“Lands Covered Under Existing Conservation Plans” section, below.)
(4)
Comment:
Because critical habitat must contain those physical or biological features essential to the conservation of the species, with the term “conservation” being considered synonymous with recovery, it appears that the same criteria used by the Service to delineate critical habitat must be incorporated into recovery plans for the Bexar County karst invertebrates. The commenter also hypothesized that the recovery of the Bexar County invertebrates will require establishment of a certain number of caves within adequate preserves that meet the parameters described in the proposed rule for critical habitat designation. Although a recovery plan has not yet been developed for these species, some of the areas proposed as critical habitat do not appear as if they will meet likely future recovery criteria for these species.
Our Response:
We recognize that our designation of critical habitat may not include all the habitat areas that might eventually be determined to be necessary for the conservation of the listed karst invertebrates. For these reasons, critical habitat designations do not signal that habitat outside the designation is unimportant or may not be recommended for attention as part of a recovery plan. Similarly, critical habitat designations made on the basis of the best information available at the time of designation will not control the direction and substance of future recovery plans, habitat conservation plans, or other species conservation planning efforts, particularly if new information available to these planning efforts calls for a different outcome. We also note that as provided for under section 4(a)(3) of the Act, we can revise our designation of critical habitat in the future if it is appropriate to do so.
Designation of critical habitat does not establish recovery criteria; that is one of the purposes of a recovery plan. Pursuant to section 4(f)(1) of the Act, the Service develops and implements plans, referred to as recovery plans, for the conservation and survival of listed species. As defined in section 3 of the Act, “conservation” means “the use of all methods and procedures which are necessary to bring any endangered species or threatened species to the point at which the measures provided pursuant to this Act are no longer necessary.” A key purpose of a recovery plan is to recognize the threats to the listed species and propose methods for removing or minimizing the threats.
A Recovery Team, including stakeholders, currently is working with the Service to prepare a draft recovery plan for these species. While the Team has discussed recovery criteria, no draft plan has been developed. When a plan is developed, the public's review and comments will be solicited before a final plan is adopted by the Service. We cannot currently say how many or which areas will be identified in the recovery plan as being important for the conservation the species.
(5)
Comment:
The Service's recommendation for the size of the critical habitat units appears to be based on the study of a single cave (Lakeline Cave in Williamson County, Texas) that may not be representative of the other karst features.
Our Response:
The recommended size for critical habitat units is not based on the results of the Lakeline Cave cricket study. The Service used the Lakeline study as one source of information that suggests small areas of native vegetation, surrounded by urban development, are not adequate to sustain the cave cricket population, which is believed to be a key to the ecology of karst invertebrates and a primary source of cave nutrients. Our designation is based on the use of the best scientific data available regarding the physical and biological features that are essential to the conservation of the species and the identification of specific areas where such features are found.
(6)
Comment:
The size of the area needed to support native plant communities is based on the need for the plants to support each other, not one karst ecosystem. Therefore, no reason exists that multiple cave/karst ecosystems cannot occur within the boundaries of one critical habitat unit, as long as the actual areas providing nutrients to each cave are encompassed.
Our Response:
We agree that the approach taken in the proposed rule of providing adequate surface plant communities for the karst ecosystem does not necessarily require more surface area to support multiple caves in close proximity. In the final rule, we revised our methods for delineating critical habitat to include multiple caves within the same smaller surface area, where appropriate. For each cave, we overlaid the areas needed to include the surface and subsurface drainages, cave cricket foraging area, and the vegetative surface community (see “Critical Habitat” section).
(7)
Comment:
The Service should consider only designating the cave cricket foraging area plus a buffer area, or about 5.34 ac, as critical habitat around each cave.
Our Response:
We agree that the immediate area around an occupied cave is very important for cave cricket foraging and other reasons, and that this area should be included in the critical habitat designation. However, there are additional physical and biological features that we have identified as essential to the conservation of the species, consistent with the definition of critical habitat in section 3 of the Act. The area recommended by the commenter would not adequately provide for the features and related primary constituent elements that we have identified as being essential to the conservation of these species (
see
“Critical Habitat” and “Primary Constituent Elements” sections, below).
(8)
Comment:
Based on the Testudo Tube Cave example in Williamson County, 31 acres (26-acre preserve plus a buffer area) may be an adequate area for critical habitat units.
Our Response:
Testudo Tube Cave Preserve in Williamson County, Texas, is surrounded by several hundred acres of undeveloped land and is adjacent to an even larger preserved area of several thousand acres, resulting in an effective “preserve” size of much larger than 31 acres. We will be interested in long-term studies of the Testudo Tube Cave Preserve that may provide additional information about the adequacy of the size of the preserve. We note also that designating critical habitat does not establish a preserve (see “Critical Habitat” section).
(9)
Comment:
Boundaries of the critical habitat units are arbitrary and not properly defined. The boundaries should be based on biology and not roads and surface features.
Our Response:
While the general size of the critical habitat unit boundaries are based on primary constituent elements needed by the species, in the proposed rule we did use roads and other surface features to make it easy for the public to identify the boundaries. In the changes to the boundaries in this final rule, we did not use surface features, but instead used specific coordinates to describe the boundaries. This allowed us to base boundaries mainly on biological, hydrological, and geological considerations, thereby delineating critical habitat areas more precisely.
(10)
Comment:
Critical habitat needs to be defined to include three new caves that have been discovered to contain listed species since the proposed rule was published.
Our Response:
Of the three caves that were discovered to contain listed species since the proposed rule was published, two (Hackberry Sink and Dancing Rattler Cave) are located in Government Canyon State Natural Area. We have determined that the management for the caves and the species in the Natural Area provides adequate special management considerations for the primary constituent elements, and consequently units within the Natural Area that we proposed for designation are not included in this final rule. (See the “Lands Covered Under Existing Conservation Plans” section for further details.) One cave (Crownridge Canyon Cave) is in a new location, but was not included in this final determination because there would have been no opportunity for public comment had we included the area in critical habitat. Under our rulemaking procedures and the Administrative Procedure Act, we would first need to propose the area for designation and seek public review and comment on such a proposal before a designation would be possible. Because of the court-approved settlement agreement that set a deadline for finalizing this rule, we did not have enough time to republish a proposed rule that might have included the Crownridge Canyon Cave in the critical habitat designation. We note that the listed species in Crownridge Canyon Cave do occur in other caves within the critical habitat designation. Although we are not able to consider including Crownridge Canyon Cave in this designation of critical habitat, we believe the cave and the associated karst ecosystem to be important to the conservation of the species. Because the cave is known to be occupied, it will be covered by applicable provisions under sections 7 (requiring Federal agencies to consult under the “jeopardy standard”), 9, and 10 of the Act.
(11)
Comment:
The Service ignored the potential for the species to occur in void spaces within the bedrock lying between caves.
Our Response:
We agree that the species occur within, and use, subsurface voids in karst rock and areas between occupied caves, and we indicated this in the proposed rule for critical habitat. However, we do not have data to quantify such areas. Using the best available data, we designated critical habitat to incorporate the specific areas on which are found the primary constituent elements of a karst ecosystem in the vicinity of caves known to be occupied by the endangered species.
(12)
Comment:
How can a cave located within an area lacking a healthy surface plant community contain an intact subsurface environment?
Our Response:
The surface vegetative community has been significantly altered by urbanization in some of the designated critical habitat units. Since the caves still contain the endangered species, we believe that the areas have maintained the primary constituent elements related to the karst subsurface environment and surface and subsurface drainages. We recognize that intensive management of the remaining surface habitat may be needed to compensate for lack of natural plant and animal communities on the surface.
Issue 2: Data Quality
(13)
Comment:
The available data used in the proposed rule is not adequate to support this critical habitat designation. There seems to be a particular lack of data on species biology, ecology, and distribution of the species and information on which to base the unit boundaries and areas.
Our Response:
As per section 4(b)(2) of the Act, we are required to designate critical habitat “on the basis of the best scientific data available,” and we believe our designation meets that requirement. In general, the biology and ecology of the karst-adapted species are not well understood. Consequently, the criteria we used to delineate critical habitat, and the areas we delineated, were based on components of the karst ecosystem for which sufficient information exists to determine their importance to the listed species, and for which specific areas can be identified and mapped. The “Information Sources” and “Criteria Used to Designate Critical Habitat” sections below provide additional information regarding the basis for our designation.
(14)
Comment:
The number of Bexar County caves and those containing listed species should be updated to the latest available information. Will the Service designate critical habitat for new locations of the listed species that will be discovered subsequent to publication of the final rule for critical habitat designation?
Our Response:
We fully agree that our knowledge of the caves in Bexar County that are known to provide habitat for endangered karst invertebrates should be as current as possible. This knowledge will help the Service evaluate the threats to the species, the status of the species, and plan for their conservation. We recognize that additional caves are likely to be found
in the future that have endangered karst invertebrates and may not be within the areas currently designated as critical habitat.
Section 4(a)(3) of the Act provides that subsequent to the designation of critical habitat, we “may, from time-to-time thereafter as appropriate, revise such designation.” Any new caves discovered to contain the listed species may be important to the conservation of the species, and we will consider them for potential future revisions of this designation, provided the available science at the time supports the designation. This would require the same procedures for public comment and full economic analysis as this final rule has followed. We note also that new areas found to be occupied by the endangered species and not included in this designation of critical habitat may be considered and included in the recovery plan being prepared for these species. Also, the species at those new locations will receive protection under sections 7 (pursuant to requirements for Federal agencies related to the “jeopardy” standard), 9, and 10 of the Act, regardless of whether the area is designated as critical habitat.
(15)
Comment:
Restricted access to private property limits the knowledge of other caves that may contain endangered karst invertebrates.
Our Response:
The help of private property owners will be essential for the recovery of these endangered karst invertebrates. Any surveys for caves or cave invertebrates on private property are completely voluntary and at the discretion of the landowner. We appreciate the cooperation the Service has received from many landowners in Bexar County who allowed geologists and biologists access. We want to continue to build positive, voluntary relationships with private landowners for the conservation of listed species.
(16)
Comment:
Does critical habitat designation comply with the Federal Data Quality Act and Service Information Quality Guidelines?
Our Response:
The U.S. Department of the Interior, of which the Fish and Wildlife Service is part, issued guidelines regarding data quality, in response to the passage of Public Law 106-554, referenced by the commenter. These guidelines, Information Quality Guidelines Pursuant to Section 515 of the Treasury and General Government Appropriations Act For Fiscal Year 2001, became effective October 1, 2002. The Service's rulemaking procedure, inclusive of this designation of critical habitat, includes a comprehensive public comment process and imposes a legal obligation on us to respond to comments on the proposed action. These procedural safeguards can ensure a thorough response to comments on quality of information. The thorough consideration required by this process generally meets the needs of the request for correction of information process, under the Federal Data Quality Act and Service Information Quality Guidelines. In the case of rulemakings and other public comment procedures, where we disseminate a study analysis or other information prior to the final rulemaking, requests for correction are considered prior to the final action. The commenter did not specifically identify how the draft economic analysis or proposed rule might not meet the criteria that the guidelines require. Regardless, we believe that this process used the best and most reliable scientific and commercial data available regarding the designation and meets the criteria of the data quality guidelines.
(17)
Comment:
The proposed rule states that of about 400 caves known in Bexar County, only 57 contain the listed species. Have the other 343 caves been surveyed?
Our Response:
The final rule has been updated to reflect the best available information on the total number of caves known from Bexar County (475 caves as of December 2002). Seventy four caves are currently known to contain listed species. Not all of the known caves in Bexar County have been adequately surveyed for invertebrates. It is likely that some of these caves will be found to contain one or more of the listed species. We also expect more caves to be discovered as additional surveys are completed.
Issue 3: Site-Specific Comments
(18)
Comment:
Many individual landowners commented that their property should be excluded from the critical habitat because it did not contain either the caves with the species or the primary constituent elements necessary for critical habitat. Several units have already been significantly disturbed from urban development and others are planned for development.
Response:
The specific properties of most of the individual landowners who expressed these concerns have been either removed from the critical habitat designation, or the amount of their property included in the designation is now significantly reduced. This is a result of the reduction in area designated in all of the units based on the updated criteria used in the final rule to determine the areas for critical habitat (refer to the “Methods” and the “Criteria Used to Identify Critical Habitat” sections of the final rule for the specific changes). All of the revised critical habitat units designated in this final rule contain one or more of the primary constituent elements essential for the conservation of these endangered species. Conservation of some species may be dependent, in part, on habitat restoration activities in some areas that have been disturbed. Such activities may include, but are not limited to, restoration of native vegetation, control of invasive species, and the installation of berms to protect the cave opening from pollutants.
(19)
Comment:
The groundwater drainage basins for Black Cat Cave and Logan's Cave (Units 13 and 17, respectively) extend beyond the boundaries of their proposed critical habitat areas. These units should be expanded to include the appropriate drainage basins. The surface water drainage area for Springtail Crevice Cave (Unit 21) extends more than 6 km outside of its proposed critical habitat area. All, or at least a significantly greater percentage, of the lower drainage area within about 2 km of the cave should be included within the critical habitat area to better protect the cave from degradation of water quality due to urbanization.
Our Response:
The subsurface drainage areas associated with the caves from units 13 and 17, and the surface drainage area for the cave in Unit 21, were delineated after the proposed rule was published (Veni 2002). These drainage areas extend outside of the boundaries of the proposed critical habitat boundaries. These areas were not included in this final determination because they were not identified in the proposed rule and, therefore, were not available for public comment. Although not included in the critical habitat designation, minimizing future impacts to the subsurface and surface drainage areas associated with these caves will likely be important for the conservation of the listed species in these caves. We have emphasized the importance of these areas in this final rule (
see
“Critical Habitat Unit Descriptions” section).
(20)
Comment:
The boundaries of Unit 20 are arbitrary, and 160 ha (395 ac) are not required to protect the species in Robber Baron Cave.
Our Response:
The boundaries of Unit 20 have been redrawn based on the cave footprint and the subsurface drainage area of the cave and reduced to include 23 ha (57 ac). The amount of Zone 1 area included in the critical habitat designation was also reduced due to a lack of information on the importance of this area to the listed species within the cave. We also reduced the area included
in the critical habitat by using coordinate data to describe the boundaries, rather than roads as used in the proposed rule.
(21)
Comment:
Several commenters requested that certain units be excluded because there are other caves with critical habitat, located in the same karst fauna region and containing the same listed species, whose surface habitat is in a more natural and less degraded state. Therefore, the Service should omit those units with degraded surface habitat, because they will not be required for conservation of these species.
Our Response:
As discussed above, all of the specific areas being designated contain one or more physical or biological features and primary constituent elements that are essential for the conservation of these endangered species and meet the definition of critical habitat as provided in section 3 of the Act. While some of the designated areas may not be in optimal condition, they are the only known locations for these species. Some of the areas may need intensive special management to restore or maintain some of the conditions important to these species. Conservation efforts involving the designated areas and other areas, including efforts taken to implement a recovery plan when one is adopted, will be dependent on the voluntary cooperation of landowners. This may include, but is not limited to, the cooperation of landowners who may voluntarily allow restoration efforts on their lands.
(22)
Comment:
Unit 1e should be divided into multiple smaller units for critical habitat.
Our Response:
We agree and the final designation divides Unit 1e, previously 341 ha (842 ac), into three smaller Units 1e1, 1e2, and 1e3 for a total area of 50 ha (124 ac) (see Table 2 below).
(23)
Comment:
How can the Service designate critical habitat for Unit 19 and Genesis Cave when the urban development on the site has already resulted in take of the species in the cave? If the unit was designated based on the alleged existence of intact subsurface environment, then why are the vegetation buffer zones necessary?
Our Response:
We determined that area designated as Unit 19 maintains the biological and physical features essential to the conservation of the species and supports one or more of the primary constituent elements. Thus it warrants inclusion in the final critical habitat designation regardless of whether “take” (as defined in Section 9 of the Act) of listed species in Unit 19 has already occurred. Critical habitat for Units 19 and 20 is designated only for the subsurface environment due to the significant surface degradation that has already occurred. We acknowledge that intense management will likely be needed in both of these units for conservation of the species. Identifying areas that contain features essential to the conservation of the species and that may require special management considerations or protection is a primary purpose of designating critical habitat.
(24)
Comment:
The Service should address how intensive management will provide nutrients and water to listed species in caves in heavily urbanized areas, such as units 12 and 19. The Service should also identify who should be responsible for this management, since critical habitat designation does not mandate special management or require removal of existing structures.
Our Response:
Under the definition of critical habitat, all of the areas being designated may require special management. Caves in heavily urbanized areas, such as those within Units 12, 19, and 20, may need more intensive management for conservation of the species than some of the other units. We anticipate that the recovery plan for these species will address the specific management strategies recommended for long-term conservation of these species. This designation does not in any way require landowners to undertake any particular management actions for the designated critical habitat or the listed species. As part of the recovery process, we anticipate working cooperatively with landowners and other partners to provide the management needed for conservation.
(25)
Comment:
The proposed rule did not clearly indicate that surface disturbances within Units 19 and 20 would not have the potential to adversely modify sub-surface critical habitat and would not be regulated under Section 7. Similarly, what is the regulatory distinction between units with both primary constituent elements and those units with only one of the primary constituent elements.
Our Response:
For critical habitat Units 19 and 20, we designated the subsurface area only as critical habitat, because of the level of disturbance that already has altered the surface habitat. Under section 7 of the Act, Federal agencies are required to insure, in consultation with the Service, that any action they authorize, fund, or carry out is not likely to jeopardize the continued existed of a listed species or result in the destruction or adverse modification of designated critical habitat. An action authorized, funded, or carried out by a Federal agency involving the surface of the land is subject to the consultation requirement of section 7, and related regulations at 50 CFR 402, if such action may affect a listed species or its designated critical habitat. The aspect of a consultation involving critical habitat would address the potential effects of a proposed Federal action on the primary constituent elements in the area covered by the consultation. For additional information about consultations and the potential Federal activities that could destroy or adversely modify critical habitat see the “Section 7 Consultation” section, below.
(26)
Comment:
Unit 12 should be deleted because the areas around Hairy Tooth and Ragin' Cajun caves are effectively protected. Big Springs Ltd., has established preserves around each cave and has developed a management plan for Hairy Tooth Cave and is considering a management plan for Ragin' Cajun Cave. Also, Unit 9 should be deleted or much reduced to exclude areas under a karst management plan by the University of Texas at San Antonio.
Our Response:
In order to consider not including an area that is the subject of a management plan, we first evaluate the plan. Key factors we evaluate include whether the plan or agreement is legally binding, the status of implementation of the plan, whether the plan specifies the management needed to ensure that primary constituent elements are appropriately protected and, if needed, improved. Along with meeting other criteria, the plan also must include a timely schedule for implementation and outline the probability that the funding source or other resources necessary to implement the management will be available. The management plan for Hairy Tooth Cave (Unit 12), which we received after the close of the comment period, did not meet the above criteria. A management plan for Ragin' Cajun Cave was not provided to us.
The University of Texas at San Antonio submitted a draft karst management plan for consideration with respect to Unit 9. This draft plan represents a very positive step for conservation of the listed karst invertebrate species. However, without a final plan, we could not make a determination that the area is receiving adequate special management, in accordance with the criteria described above. (
See
the “Lands Covered Under Existing Conservation Plans” for additional information on our process.) Therefore, Unit 9 is part of the final designation, although its size has been reduced (for other reasons) from the
proposed amount of 71 ha (175 ac) to 16 ha (40 ac) in this final rule. The procedures for submitting management plans for possible exclusion of specific areas were clearly described in the proposed rule.
Issue 4: Economic Issues
(27)
Comment:
The draft economic analysis understates the economic impact from the critical habitat designation because it failed to adequately consider effects from: (1) Greater amounts of technical assistance and administrative tasks than estimated; (2) greater numbers of informal and formal section 7 consultations than estimated because of a vast understatement of Federal involvement in private projects; (3) increased difficulty in obtaining state and/or county approval for development; (4) project modifications and delays for planned developments; (5) development of biological assessments; (6) reduced property values; and (7) increased mitigation costs. Generally, the baseline approach used in the draft economic analysis underestimates the impacts to all development activities, whether or not Federal involvement is presumed.
Our Response:
Minor modifications were made in the final economic analysis of the proposed rule to reflect increased technical assistance in one unit and to the cost of technical assistance related to Clean Water Act activities. We believe the estimates of formal and informal consultations in the final economic analysis reflect numbers that can be reasonably anticipated. We do not anticipate any increased difficulty in obtaining State or county approvals for development. While uncertainties about the impacts of the critical habitat designation and the perception that the designation will impose land use restrictions could temporarily foster this result, this effect is likely to be temporary in nature as the uncertainties and perceptions dissipate or become clarified over time.
We do not believe that critical habitat designation will impose additional project modifications and delays for projects, including preparation of biological assessments. Additional requirements associated with critical habitat designation apply solely to Federal actions, and since this designation only involves occupied habitat, then the section 7 requirements would have to be met pursuant to consideration of “jeopardy standard” regardless of the presence of critical habitat. We do not believe that the designation of critical habitat, when occupied by the listed species, should have any real effect on property value, because it only applies to those activities that involve a Federal action. However, we do recognize that there can be a perceived effect which could adversely affect property values. We will, through outreach and education, do all we can to correct this perception.
We believe mitigation costs associated with critical habitat designation were accurately estimated in the final economic analysis. The anticipated number of HCPs was increased from five to eight, and the cost of purchasing and managing mitigation lands due to the development of HCPs was estimated. The analysis used standard methods for analyzing the economic impacts. These methods have been used in past designations throughout the United States and have generally been found to be sufficient.
(28)
Comment:
The draft economic analysis is clearly prepared to show that minimal effects will be felt by the designation and should be rejected because it does not take an objective view of the matter under consideration. The information sources referenced do not include any discussions with private landowners.
Our Response:
The analysis used standard methods for analyzing economic impacts. These methods have been used in past designations throughout the United States and have generally been found to be sufficient. Also, the final economic analysis of the proposed rule considers information gathered from interviews with individual property owners who submitted comments on the draft analysis.
(29)
Comment:
The level of predicted consultations appears to be based on the assumption that only commercial, as opposed to residential, development would trigger consultations, and the only anticipated Federal nexus for development was a party seeking an HCP.
Our Response:
We apologize if the assumptions were not clear. We have clarified the assumptions in the final economic analysis.
(30)
Comment:
The draft economic analysis discounts entirely broader regional impacts, focusing only on the costs of consultation. The setting aside of land and delaying and increasing the costs of a variety of projects and activities will undoubtedly have a broader impact. In its draft economic analysis for the Kauai Cave wolf spider, the Service considered some of these broader economic impacts and determined that the impact of designating less than half the acreage proposed in Bexar County could be as high as $1.9 million. This difference in estimated costs is attributable to differences in methodology.
Our Response:
We want to stress that the designation of critical habitat does not “set aside” land and does not create parks or preserves. We believe the economic analysis fairly estimated the costs of critical habitat designation in Bexar County (
see
our response to Comment 27). The final economic analysis of the proposed rule clarifies the methods used.
(31)
Comment:
Many landowners commented that their individual properties were of high economic value and the designation of critical habitat would substantially impact the future value and development potential of their properties. For this reason, the economic impact on individual property owners, in at least some instances, should outweigh the biological benefits of the designation of critical habitat.
Our Response:
The regulatory requirements involving critical habitat apply only to those actions authorized, funded, or carried out by a Federal agency. We do recognize, however, that there can be a perceived effect which could influence property values, but believe any such effect is likely to be temporary in nature as the uncertainties and perceptions dissipate or become clarified over time. We will, through outreach and education, do all we can to correct this perception. We believe that the economic analysis appropriately considered the potential economic impacts of the proposed designation. Further, reductions in the amount of critical habitat in this final designation have resulted in a significant decrease in the amount of private land being designated.
(32)
Comment:
The draft economic analysis evaluates the effect of the total section 7 costs for individual units and then spreads those costs over the entire population of Bexar County. If these costs are attributed to the individual landowners in a single unit they would have a much greater impact. For instance, there are eight landowners in Unit 16, and the economic analysis is defective unless it measures the effects on those individual landowners.
Our Response:
The analysis uses standard methods for analyzing the economic impacts of designating the areas included in our proposed rulemaking. These methods have been used in past designations throughout the United States and have generally been found to be sufficient. Time constraints prevented us from applying economic costs to individual property owners. We note also that the size of each unit designated is substantially reduced from what we proposed,
resulting from consideration of comments received and refinements in our methodology for identifying and mapping areas that meet the Act's definition of critical habitat. For instance, for Unit 16 our proposal included 61 ha (152 ac), whereas our final designation for that unit is 16 ha (40 acres).
(33)
Comment:
The draft economic analysis states that all of the critical habitat is over the Edwards Aquifer and then states which units are over the recharge zone. It isn't clear that only the units over the recharge zone get the protection measures that are listed. If the analysis assumed that all of the units get the same level of Edwards Aquifer protection, reevaluation of the numbers may be warranted.
Our Response:
The draft economic analysis credited the protections only to those units in the recharge zone. We hope this point is adequately clarified in the final economic analysis of the proposed rule.
(34)
Comment:
For Unit 9, the draft economic analysis estimates only one technical assistance effort is anticipated and that no project modifications are anticipated. One request for assistance has already occurred, and probably one or two more will be required. In addition, a considerable amount of modification to University of Texas—San Antonio's plans in Unit 9 will have to occur to be in compliance with the proposed designation of critical habitat.
Our Response:
The Service agrees that the effort was underestimated and corrections in the final economic analysis of the proposed rule have been made to reflect this. The Service agrees that if the proposed activities involve a Federal action, then modification of the proposed action may be needed. However, since this designation only involves occupied habitat, then the section 7 consultation requirements would have to be met (for the “jeopardy standard”) regardless of the designation of critical habitat, and based on our experience in other situations, the outcome of such consultation is likely to be unchanged when it includes critical habitat.
(35)
Comment:
The estimates in Exhibit 4-4, page 44 (of the draft economic analysis) for anticipated costs to the Service, third parties, and the action agency do not cover the costs to date or future costs for UTSA in Unit 9, which are expected to be substantial.
Our Response:
The final economic analysis of the proposed rule has been modified to incorporate expected costs to UTSA that would result from section 7 consultation related to development.
(36)
Comment:
The draft economic analysis does not adequately address the tremendous economic benefits of designating critical habitat, for example, the benefits to water supply protection for area residents.
Our Response:
The value of economic benefits are difficult to estimate. The potential benefits of designating critical habitat are described subjectively in section 5 of the final economic analysis of the proposed rule.
(37)
Comment:
Landowners for Unit 12 provided specific value data to show a higher economic impact of the designation than provided in the economic analysis.
Our Response:
The economic analysis includes consideration of a potential HCP for private development within this unit. Thus the comment is not inconsistent with the assumptions of the analysis. We do not expect costs to be greater than those represented by the formulation and implementation of the expected HCP.
Issue 5: Other Issues and Comments
(38)
Comment:
One commenter requested additional time so that the taxonomic description of a new subspecies of
Rhadine infernalis
can be completed.
Our Response:
The Service is required to designate critical habitat for the Bexar County invertebrates within the time frame specified in the court settlement agreement. We have used the best scientific data available in making this designation.
(39)
Comment:
The City of San Antonio should be provided more exact cave locations for planning and protection of habitat, and to avoid inadvertent damage by the City.
Our Response:
The Service and the City of San Antonio regularly exchange information for conservation of listed species. We understand that legally, the City may not be able to keep the cave locations confidential if we provided them, and having the locations generally known would pose an unacceptable risk of vandalism to the caves. Anyone may contact the Service for technical assistance to ensure their activities are consistent with conservation of these species. Helping make the public aware of the sensitive areas inhabited by these species is one of the most significant benefits of this designation. In addition to these critical habitat units, there are likely other localities where these species occur, of which we are not aware, or have not yet been discovered. Although they are not included in this designation, they are likely to be important for conservation of the species and should be considered in planning land management and development activities. We look forward to working with the City, and other partners, for management of their lands for the mutual benefit of the City's citizens and the conservation of the listed species.
(40)
Comment:
The Service should change the name of the Alamo Heights Karst Fauna Region so the public is not misled to believe the City of Alamo Heights is in critical habitat.
Our Response:
The name of the Karst Fauna Region was taken from a report by George Veni and Associates (1994), which delineates separate geological regions in the San Antonio area. We recognize that the City of Alamo Heights is not within any of the units designated as critical habitat and regret any confusion the name of the faunal region might have caused. We have not used the Karst Faunal Region names in this final rule.
(41)
Comment:
Does critical habitat designation comply with Environmental Justice laws?
Our Response:
Executive Order 12898, Federal Actions to Address Environmental Justice in Minority Populations and Low-Income Populations, requires that each Federal agency make achieving environmental justice part of its mission by identifying and addressing, as appropriate, disproportionately high and adverse human health or environmental effects of its programs, policies, and activities on minorities and low-income populations. We do not believe that the designation of critical habitat for endangered and threatened species results in any changes to human health or environmental effects on surrounding human populations, regardless of their socioeconomic characterization. As such, we do not believe that Executive Order 12898 applies to critical habitat designations.
(42)
Comment:
The required public notice to interested parties was not satisfied because numerous mailings were returned because of invalid zip codes.
Our Response:
We made the best effort to notify all individual landowners involved directly. We sent the letters announcing the proposed rule and requesting comments to over 1,500 interested parties. Of those, about 200 were returned because of out-of-date addresses. We attempted to update addresses and remove duplicate addresses. We followed this mailing with over 1,200 postcards announcing the availability of the draft economic analysis and extension of the comment period. We regret that some of the attempts to contact interested parties
through the mail were unsuccessful. In addition to those efforts, the required public notices were published in the local newspaper. We also issued a news release, and there was coverage in the local newspaper and in other news media. Consequently, we believe we satisfactorily met the requirements for public notice to interested parties.
(43)
Comment:
The Texas Parks and Wildlife Department (TPWD) and the Department of Defense (DOD) submitted karst management plans for Government Canyon State Natural Area (GCSNA) and Camp Bullis, respectively, during the public comment period and requested that their properties be excluded from the final critical habitat designation.
Our Response:
We reviewed the management plans submitted for both Camp Bullis and GCSNA. On the basis of our evaluation of these plans, we determined that they provide adequate special management and have not included the areas involved in the final designation of critical habitat. (See “Lands Covered Under Existing Conservation Plans” section for more information.)
Peer Review
In accordance with our peer review policy published on July 1, 1994 (59 FR 34270), we solicited independent opinions from knowledgeable individuals with expertise in one or several fields, including familiarity with the species, familiarity with the geographic region in which the species occurs, and familiarity with the principles of conservation biology. Only one of the eleven peer reviewers requested to review the proposed rule submitted comments. Overall the peer reviewer found the proposed rule to be an “excellent, comprehensive document.” The following specific comments were provided by the peer reviewer.
(44)
Comment:
The 36 ha (90 ac) zone of vegetation surrounding each known cave or cave complex should be adequate to preserve foraging habitat for cave crickets.
Our Response:
In this final rule we have significantly reduced the areas around occupied caves that are included in the critical habitat designation. However, in most cases, the critical habitat boundaries were drawn to include a 50 m (164 ft) area plus a buffer, and best available information indicates that most cave crickets forage within 50 m (164 ft) of cave entrances (see “Background” section for additional information).
(45)
Comment:
The reviewer stated that habitat requirements described in the proposed rule seemed fine; however, the reviewer expressed concern that active management may be required to maintain natural surface habitat for the benefit of the subsurface environment. The reviewer also expressed concern about the encroachment of red imported fire ants and the impacts of predation on and competition with cave crickets and asked if there is a provision for dealing with this threat in the critical habitat units.
Our Response:
We recognize the impact that fire ants likely have on listed karst invertebrates and the need for intense management to control this threat. The designation of critical habitat recognizes that these areas may need special management, however, the designation does not require any particular land management activities. Specific actions for management recommendations will likely be included in the future recovery plan for these species. We will work with landowners on a case-by-case basis to assist in land management provisions to protect the karst environment that supports the listed Bexar County invertebrates.
(46)
Comment:
There are no dispersal corridors between these habitat units to provide opportunities for movement of individuals between cave cricket populations.
Our Response:
We know that dispersal corridors are likely important for the long-term maintenance of cave cricket populations (
see
Background section for discussion). However, we lack the necessary information to adequately quantify the specific locations of such corridors and therefore have not included them in this critical habitat designation.
(47)
Comment:
The commenter recommends deleting the reference in the “Background” section to a study concerning
Ceuthophilu gracilipes
, another species of cave crickets, because it is not appropriate in the context in which it was used.
Our Response:
We deleted this reference, which had been included in our proposed designation, and updated the “Background” section of this final rule as suggested.
Summary of Changes From the Proposed Rule
On the basis of public comments, we reviewed our methodology for determining the extent of critical habitat designation for the Bexar County karst invertebrates. Consequently, we refined the boundaries of our original proposed critical habitat units for this final designation and clarified our description of the methodology and rationale used in defining the critical habitat boundaries. Overall, these changes resulted in designating 431 ha (1,063 ac) in 22 units as critical habitat, as compared to our proposed designation of 3,857 ha (9,516 ac) in 25 units. Table 2 provides a unit-by-unit list of the changes in this final rule, which are summarized below.
In the proposed rule, we delineated critical habitat boundaries on the basis of the following criteria: Known occupied caves; the cave footprint; surface/subsurface drainage areas associated with the occupied cave; the cave cricket foraging area plus a buffer; the contiguous karst deposit associated with the occupied cave; and a minimum of 36 ha (90 ac), where possible, to support dominant, subdominant, and rare plant species. In the final rule, we revised several of these criteria. We reduced the minimum area needed to support surface vegetation from 36 ha (90 ac) to 16 ha (40 ac), which is the minimum area we determined is needed to support 15 of the 24 plant species common to the Edwards Plateau, including the 7 species with the highest dominance values, as listed in Van Auken
et al.
(1980). We did not include an estimated area to support nine of the rarer plant species in our consideration of this minimum area, because of a lack of definitive information on the importance of such species to the functioning of the karst ecosystem. These nine species all have importance values of less than 1.0 and needed an area of approximately 20 to 80 ha (49 to 198 ac) to maintain their populations. We also reduced the criterion for the amount of contiguous karst deposit surrounding occupied caves. In the proposed rule, we delineated the unit boundaries to maximize the amount of contiguous karst deposit we estimated was necessary to provide for subsurface movement of listed species between and around occupied caves. However, because of lack of data allowing us to quantify the extent of subsurface karst needed to maintain populations of these species, in the final rule we delineated the boundaries to maximize the amount of subsurface karst deposit underlying the cave footprint, drainage areas, cave cricket foraging area plus buffer, and 16 ha (40 ac) vegetation area only. As a result of these revisions, the size of most units was reduced significantly (Table 2). (
See
“Criteria Used to Designate Critical Habitat” section for additional details.)
In addition to the changes in criteria, we also completely removed six units that had been proposed for designation (Units 1a, 1b, 1c, 1d, 10, and 11) from the final designation. Units 1a-1d were
located on the Government Canyon State Natural Area (GCSNA) and the majority of Unit 10 and all of Unit 11 were located on Department of Defense land at Camp Bullis. We did not include these six units in the final designation because we determined that the conservation plans for these areas provide adequate special management and protection, such that the areas do not meet the definition of critical habitat under section 3(5)(A)(i) of the Act. We also excluded these areas from designation based on section 4(b)(2). (See “Lands Covered Under Existing Conservation Plans” section.) Two of the nine species, the Government Canyon Bat Cave meshweaver and the Government Canyon Bat Cave spider, occur only in caves on the GCSNA. As a result of not including in the final designation the four units originally proposed on the GCSNA, no critical habitat is being designated for these two species.
As a result of applying our revisions of the criteria used to delineate the unit boundaries (as described above) we separated two units identified in the proposed rule into separate, smaller units in this final rule. Specifically, Unit 1e as described in the proposed rule has been separated into three smaller units (Units 1e1, 1e2, and 1e3), and we separated Unit 8 into Units 8a and 8b. Removing six units, separating Unit 1e into three smaller units and Unit 8 into two smaller units resulted in a net change of three fewer units in this final rule as compared to the proposed rule.
Table 2.—Changes in Unit Number and Unit Area Between Proposed and Final Rules Designating Critical Habitat for Seven of the Nine Bexar County Karst Invertebrates
Proposed rule
Unit #
Total area of unit
hectares (ha); acres (ac)
Final rule
Unit #
Total area of unit
hectares (ha); acres (ac)
1a
1b
76 ha; 188 ac
47 ha; 116 ac
1a
1b
Government Canyon State Natural Area—excluded from critical habitat.
1c
47 ha; 116 ac
1c
1d
47 ha; 116 ac
1d
1e
341 ha; 842 ac
1e1
15 ha; 38 ac.
1e2
16 ha; 40 ac.
1e3
19 ha; 46 ac.
2
99 ha; 245 ac
2
37 ha; 92 ac.
3
63 ha; 154 ac
3
17 ha; 41 ac.
4
63; ha; 154 ac
4
16 ha; 40 ac.
5
47 ha; 116 ac
5
16 ha; 40 ac.
6
45 ha; 111 ac
6
16 ha; 40 ac.
7
50 ha; 123 ac
7
16 ha; 40 ac.
8
174 ha; 428 ac
8a
16 ha; 40 ac.
8b
28 ha; 69 ac.
9
71 ha; 175 ac
9
16 ha; 40 ac.
10
367 ha; 906 ac
10
Camp Bullis—excluded from critical habitat.
11
1,273 ha; 3,143 ac
11
Camp Bullis—excluded from critical habitat.
12
105 ha; 258 ac
12
21 ha; 51 ac.
13
51 ha; 125 ac
13
16 ha; 40 ac.
14
173 ha; 426 ac
14
26 ha; 64 ac.
15
195 ha; 481 ac
15
34 ha; 85 ac.
16
61 ha; 152 ac
16
16 ha; 40 ac.
17
48 ha; 118 ac
17
16 ha; 40 ac.
18
40 ha; 100 ac
18
16 ha; 40 ac.
19
59 ha; 146 ac
19
5 ha; 12 ac.
20
160 ha; 395 ac
20
23 ha; 57 ac.
21
155 ha; 382 ac
21
27 ha; 68 ac.
Totals: 25 units; 3,857 ha; 9,516 ac
(1) 22 units; 431 ha; 1,063 ac.
Critical Habitat
Critical habitat is defined in section 3(5)(A) of the Act as—(i) the specific areas within the geographical area occupied by a species, at the time it is listed in accordance with the Act, on which are found those physical or biological features (I) essential to the conservation of the species and (II) which may require special management considerations or protection; and (ii) specific areas outside the geographical area occupied by a species at the time it is listed, upon a determination that such areas are essential for the conservation of the species. “Conservation,” as defined by section 3(3) of the Act, means the use of all methods and procedures which are necessary to bring an endangered or a threatened species to the point that measures provided pursuant to the Act are no longer necessary.
Section 7(a)(2) of the Act requires that Federal agencies shall, in consultation with the Service, insure that any action they authorize, fund, or carry out is not likely to jeopardize the continued existence of a listed species or result in the destruction or adverse modification of critical habitat. Section 7 also requires conferences on Federal actions that are likely to result in the destruction or adverse modification of proposed critical habitat. Aside from the added protection that may be provided under section 7, the Act does not provide other forms of protection to lands designated as critical habitats. Consultation under section 7 of the Act does not apply to activities on private or other non-Federal lands that do not involve a Federal nexus (
i.e.
, Federal funding or authorization), and consequently critical habitat designation does not afford any additional regulatory protection or result in additional regulatory requirements under the Act in those circumstances. (
See
“Effects of Critical Habitat
Designation” for further discussion of consultations under section 7 of the Act.)
Critical habitat provides nonregulatory benefits to the species by informing the public and private sectors of areas that are important for species conservation, and where such conservation actions would be most effective. Designation of critical habitat can help focus conservation activities for a listed species by identifying areas that contain the physical and biological features that are essential for the conservation of that species, and can alert the public and land-managing agencies to the importance of those areas. Critical habitat also identifies areas that may require special management considerations or protection, and may help provide protection to areas where significant threats to the species have been identified, by helping people avoid causing accidental damage to such areas.
To be included in a critical habitat designation, the habitat must be “essential to the conservation of the species.” Critical habitat designations identify, to the extent known and using the best scientific and commercial data available, habitat areas that provide essential life cycle needs of the species (such as areas on which are found the primary constituent elements, as defined at 50 CFR 424.12(b)). Section 3(5)(C) of the Act states that, “Except in those circumstances determined by the Secretary, critical habitat shall not include the entire geographical area which can be occupied” by the listed species. In addition, our regulations (50 CFR 424.12(e)) state that “The Secretary shall designate as critical habitat areas outside the geographic area presently occupied by the species only when a designation limited to its present range would be inadequate to ensure the conservation of the species.”
Section 4 (b)(2) of the Act requires that we take into consideration the economic impact, and any other relevant impact, of specifying any particular areas as critical habitat. We may exclude areas from critical habitat designation when the benefits of exclusion outweigh the benefits of including the areas within critical habitat, provided the exclusion will not result in extinction of the species.
Our Policy on Information Standards Under the Endangered Species Act, published on July 1, 1994 (59 FR 34271), provides criteria, establishes procedures, and provides guidance to ensure that decisions made by the Service represent the best scientific and commercial data available. It requires that our biologists, to the extent consistent with the Act and with the use of the best scientific and commercial data available, use primary and original sources of information as the basis for recommendations to designate critical habitat. When determining which areas are critical habitat, a primary source of information should, at a minimum, be the listing rule for the species. Additional information may be obtained from a recovery plan (if available), articles in peer-reviewed journals, conservation plans developed by States and counties, scientific status surveys and studies, and biological assessments or other unpublished reports, and discussion with experts.
Section 4 of the Act requires that we designate critical habitat on the basis of what we know at the time of designation. Since much of the cave-forming rock is located on private property in areas that have not been adequately surveyed, additional populations for some of these species are likely to exist and may be discovered over time. We recognize that our designation of critical habitat for these species may not include all of the habitat areas that may eventually be determined to be necessary for the conservation of the species. For these reasons, this critical habitat designation should not be interpreted to mean that habitat outside the designation is unimportant or may not be required for conservation of the species. Critical habitat designations made on the basis of the best available information at the time of designation will not control the direction and substance of future recovery plans, habitat conservation plans (HCPs), or other species conservation planning and recovery efforts if new information available to these efforts calls for a different outcome.
Habitat of the listed species that is not included in this critical habitat designation will continue to be subject to conservation actions implemented by Federal agencies under section 7(a)(1) of the Act, which directs Federal agencies to utilize their authorities to carry out programs for the conservation of threatened and endangered species. Habitat outside the designation also will continue to receive regulatory protections afforded by the section 7(a)(2) jeopardy standard, which requires each Federal agency to insure, in consultation with the Service, that any action it authorizes, funds, or carries out is not likely to “jeopardize the continued existence” of a listed species. To achieve this objective, action agencies must consult with us whenever a Federal action “may affect” a listed species. This requirement applies regardless of whether critical habitat is designated, and Federally funded or assisted projects affecting listed species outside their designated critical habitat areas may still result in jeopardy findings in some cases.
The applicability of the section 9 section take prohibition is not altered by the designation of critical habitat. Section 9 makes it unlawful for any person to “take” (defined broadly in section 3 as “harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in any such conduct”) a listed wildlife species. Under section 10(a) of the Act, the Service may issue a permit to a non-Federal entity authorizing “take” if certain conditions are met. These conditions include a finding by the Service that such take is incidental to otherwise legal conduct, and that the take “will not appreciably reduce the likelihood of the survival and recovery of the species in the wild.” The issuance criteria for such take permits also require applicants to minimize and mitigate the effects of their permitted actions, to the maximum extent practicable.
Primary Constituent Elements
In accordance with section 3(5)(A) of the Act and regulations at 50 CFR 424.12(b), in determining which areas to designate as critical habitat, we consider those physical and biological features that are essential to the conservation of the species and that may require special management consideration or protection. As described in our regulations, these features include, but are not limited to, the following:
(1) Space for individual and population growth, and for normal behavior;
(2) Food, water, air, light, minerals, or other nutritional or physiological requirements;
(3) Cover or shelter;
(4) Sites for breeding, reproduction, and rearing of offspring, and generally;
(5) Habitats that are protected from disturbance or are representative of the historic geographical and ecological distributions of a species.
Our regulations at 50 CFR 424.12(b) further direct that, when considering the designation of critical habitat, we are to focus on the principal biological or physical constituent elements within the defined area that are essential to the conservation of the species, and we are to list known primary constituent elements with the critical habitat description. Our regulations describe known primary constituent elements in terms that are more specific than the
description of physical and biological features. Specifically, our regulations state that primary constituent elements may include, but are not limited to, the following: Roost sites, nesting grounds, spawning sites, feeding sites, seasonal wetland or dryland, water quality or quantity, host species of plant pollinator, geological formation, vegetation type, tide, and specific soil types.
Using the best scientific information available to us, we have determined that the primary constituent elements required by the karst invertebrates consist of: (1) The physical features of karst-forming rock containing subterranean spaces with stable temperatures, high humidities (near saturation) and suitable substrates (for example, spaces between and underneath rocks suitable for foraging and sheltering); and (2) the biological features of a healthy surface community of native plants (for example, juniper-oak woodland) and animals (for example, cave crickets) living in and near the karst feature that provide nutrient input and buffer the karst ecosystem from adverse effects (from, for example, nonnative species invasions, contaminants, and fluctuations in temperature and humidity).
Information Sources
As required by the Act and regulations (section 4(b)(2) and 50 CFR 424.12, respectively), we used the best scientific information available to determine critical habitat areas that contain the physical and biological features and primary constituent elements that are essential for the conservation of the karst invertebrate species. This information included: (1) Peer-reviewed scientific publications; (2) the final listing rule for the nine Bexar County karst invertebrate species (65 FR 81419); (3) unpublished field data, survey reports, notes, and communications from qualified biologists or experts; (4) published descriptions of the regional geology (Soil Conservation Service 1962; Veni 1988, 1994, 2002); and (5) recent digital orthophotographs (March 2001) and parcel maps (generated in early 2002) obtained from the Bexar County Appraisal District to determine the current status of habitat surrounding the known occupied caves.
In the proposed rule, we referred to Veni's 1994 karst zone maps to ensure that the majority of the lands within each proposed unit overlaid a contiguous deposit of karst-bearing rock either known to contain the listed species (Zone 1) and/or having a high probability of suitable habitat for the listed species (Zone 2) to maintain subsurface connectivity for species movement throughout the contiguous karst deposit. Recognizing that a significant amount of additional information has become available, either as a result of the discovery of new caves containing the listed species, or additional biological surveys conducted in previously mapped caves and/or as a result of the release of information not available at the time of the 1994 report, we contracted with George Veni & Associates to re-evaluate and, where necessary, redraw the boundaries of the Bexar County karst zones. The resulting report (Veni 2002) also estimated the surface and subsurface drainage areas associated with each occupied cave in Bexar County with the exception of several caves which occur on cliffs and several for which sufficient information was not available. We received the report during the public comment period and used the information to ensure that each unit overlaid a contiguous deposit of karst-bearing rock and that the estimated drainage basins associated with each occupied cave were, where possible, designated as critical habitat. Contiguous deposits of karst-bearing rock associated with occupied caves subterranean spaces were included to protect subsurface voids believed to maintain populations of the listed species and provide for species movement. The drainage basins associated with occupied caves were included in order to protect the quantity and quality of water entering the karst ecosystem which, in turn, maintains stable temperatures and high humidities required by the listed species and protects the system from contamination.
Information on the status and location of occupied caves was obtained from presence/absence survey reports submitted during project consultations conducted with the Service under section 7 of the Act, annual reports on research and conservation activities conducted under a section 10(a)(1)(A) scientific permit, section 6 species status reports, and literature published in peer reviewed journals. Survey reports and scientific permit annual reports typically contained cave location information in the form of a cave location indicated on a U.S. Geological Survey topographic maps and/or UTM coordinates, and a map of the cave footprint.
To improve the accuracy of our cave location information, we submitted a request to the Texas Speleological Survey (TSS) for any available digital location data (UTM coordinates) for Bexar County caves known to contain one or more of the nine endangered species. TSS is a non-profit corporation established in 1961 to collect, organize, and maintain information on Texas caves and karst for scientific, educational, and conservation purposes, and to support safe and responsible cave exploration, and is affiliated with the Texas Memorial Museum, the Texas Speleological Association, and the National Speleological Society. TSS provided the majority of the digital location data, and reviewed and confirmed our location data for caves where no digital information was available. The precision of the locations for which digital location data were available ranges from 1 m to 10 m (3ft to 33 ft) and data documented on topographic maps was estimated to be accurate to within 10 m to 20 m (33 ft to 66 ft). This variability in precision was taken into account when delineating unit boundaries. We further agreed that any requests for such information would be directed to TSS as owners of the data. The precise location of the caves within each unit is not specified on the critical habitat maps in order to protect these caves from potential vandalism and to protect private landowners from potential increases in trespassing.
Criteria Used To Delineate Critical Habitat
Using the best scientific data available (as summarized in the “Background” section), we developed the following criteria to identify and delineate lands for designation as critical habitat: caves known to be occupied by one or more of the listed karst invertebrate species; the cave footprint; the surface and subsurface drainage areas associated with each cave, to the extent possible; a 150 m (492 ft) area around each cave to encompass the cave cricket foraging area of 50 m (164 ft) on the surface, measured from the cave entrance(s) and a 100 m (328 ft) area around the cave cricket foraging area to buffer the animal community, including cave crickets, against the effects of urban edges and red imported fire ant invasion; and, where possible, a minimum of 16 ha (40 ac) around each cave or cave cluster. This minimum 16 ha core area consists of a minimum 13 ha (33 ac) needed to support at least 15 of 24 species of the vegetative community commonly found on the Edwards Plateau, plus a 3 ha (7 ac) area to buffer the vegetative community against edge effects associated with urban disturbances. This surface area also acts to incorporate areas of contiguous karst deposit around an occupied cave, which likely contains the listed species that occupy the cave.
In several instances (Units 2, 13, and 21), the surface or subsurface drainage basin associated with the occupied cave, as defined by Veni (2002), extends outside of the area originally designated in the proposed rule and therefore was not included in the final rule (
see
“Critical Habitat Unit Descriptions” section). Also, in several instances (Units 1e1, 3, 6, 8b, and 17), the cave, cave footprint, and portions of the cave cricket foraging area plus buffer, the drainage basins, and the 16-ha (40-ac) vegetative area are located on lands protected under the La Cantera HCP which were not included in the designation (see “Unit Description” and Lands Covered Under Existing Conservation Plans” sections). The critical habitat area encompassing Robber Baron Cave (Unit 20) includes both the known and estimated extent of the cave's footprint. This cave is a complex maze cave consisting of approximately 1.51 km (0.94 mi) of passages known within a square area approximately 100 m (328 ft) on each side (Veni 1988). Prior to the extensive development that has occurred in the area, the cave's footprint was estimated to extend at least 100 m (328 ft) farther east to a water well, 600 m (1,969 ft) southwest to a now-sealed, extensive maze cave and about 1.2 km (0.75 mi) to the southwest to another well (Veni 1988). Exploration and mapping of these possible passages is continuing under the direction of the Texas Cave Management Association, which owns the cave entrance.
Critical Habitat Delineation
Lands designated as critical habitat for the seven endangered karst invertebrates occur in 22 separate units, with a total area of approximately 431 ha (1,063 ac). The lands within the critical habitat units are under private, city, and State ownership. Table 3 lists the known occupied caves, the total critical habitat unit area, land ownership, and the listed species that occur within each designated unit. Table 4 shows the listed species and the critical habitat unit(s) where they occur.
Each critical habitat unit contains one or more of the primary constituent elements needed by the karst invertebrate species. The “Critical Habitat Unit Descriptions” section (below) provides a description of lands within each unit and a description of how unit boundaries were delineated.
Areas within the boundaries of mapped units that have existing human-constructed, above-ground, impervious structures do not contain the primary constituent elements and are not considered to be critical habitat. Such features and structures include, but are not limited to, buildings and paved roads. However, subsurface areas under these structures are considered to be critical habitat since subterranean spaces containing these species or transmitting moisture and nutrients through the karst ecosystem extend, in some cases, underneath these existing human-constructed structures. Landscaped areas associated with existing human-constructed structures also are also not considered critical habitat because they do not contain the primary constituent elements. Although not considered to be critical habitat, these landscaped areas may provide some foraging area for cave crickets and other trogloxenes which are an important source of nutrients to the karst ecosystem.
Table 3.—Known Occupied Caves, Land Ownership and Listed Species That Occur Within Each Critical Habitat Unit Designated for One or More of the Endangered Bexar County Karst Invertebrates
Unit
Known occupied caves in unit
Total area of unit
Ownership
Listed species in unit
1e1
Pig Cave
San Antonio Ranch Pit
15 ha (38 ac)
Private, city
Rhadine exilis
R. infernalis
Batrisodes venyivi
1e2
Continental Cave
16 ha (40 ac)
City
R. infernalis
1e3
Creek Bank Cave
Tight Cave
19 ha (46 ac)
Private, city
R. exilis
2
Logan's Cave
Madla's Drop Cave
37 ha (92 ac)
Private
Cicurina madla
R. exilis
R. infernalis
3
Helotes Blowhole *
Helotes Hilltop Cave *
17 ha (41 ac)
Private
C. madla
R. exilis
R. infernalis
B. venyivi
4
Kamikazi Cricket Cave
16 ha (40 ac)
Private
R. exilis
R. infernalis
5
Christmas Cave
16 ha (40 ac)
Private
C. madla
R. exilis
R. infernalis
B. venyivi
6
John Wagner Ranch
Cave No. 3 *
16 ha (40 ac)
Private, city
R. exilis
R. infernalis
7
Young Cave No. 1
16 ha (40 ac)
Private
R. exilis
8a
Three Fingers Cave
16 ha (40 ac)
Private
R. exilis
R. infernalis
8b
Hills and Dales Pit *
Robber's Cave
28 ha (69 ac)
Private, city
C. madla
R. infernalis
R. exilis
9
Mastodon Pit
16 ha (40 ac)
State
R. exilis
12
Hairy Tooth Cave
Ragin' Cajun Cave
21 ha (51 ac)
Private
R. exilis
13
Black Cat Cave
16 ha (40 ac)
Private
R. exilis
14
Game Pasture Cave No. 1
King Toad Cave
Stevens Ranch Trash Hole Cave
26 ha (64 ac)
Private
R. infernalis
15
Braken Bat Cave
Isopit
34 ha (85 ac)
Private
Cicurina venii
R. infernalis
Obvious Little Cave
Wurzbach Bat Cave
16
Caracol Creek Coon Cave
16 ha (40 ac)
Private
R. infernalis
17
Madla's Cave *
16 ha (40 ac)
Private
C. madla
R. infernalis
18
Mattke Cave
Scorpion Cave
16 ha (40 ac)
Private
R. infernalis
19
Genesis Cave
5 ha (12 ac)
Private
R. infernalis
20
Robber Baron Cave
23 ha (57 ac)
Private
Texella cokendolpheri
Cicurina baronia
21
Hornet's Last Laugh Pit
Kick Start Cave
Springtail Crevice
27 ha (68 ac)
City, Private
R. exilis
Totals
22
31 caves
431 ha (1,063 ac)
* Indicates caves and associated lands protected by management under La Cantera's Section 10 permit; these are not included in this designation or in the area figures.
Table 4.—List of the Nine Endangered Bexar County Karst Invertebrates and the Critical Habitat Units Within Which They Occur
Species name
Critical habitat unit(s) of occurrence
Braken Bat Cave meshweaver (
Cicurina venii
)
15
Cokendolpher cave harvestman (
Texella cokendolpheri
)
20
Government Canyon Bat Cave meshweaver (
Cicurina vespera
)
No critical habitat designated.
Government Canyon Bat Cave spider (
Neoleptoneta microps
)
No critical habitat designated.
Madla Cave meshweaver (
Cicurina madla
)
2, 3, 5, 8b, 17
Robber Baron Cave meshweaver (
Cicurina baronia
)
20
Beetle (
Rhadine exilis
)
1e1, 1e3, 2, 3, 4, 5, 6, 7, 8a, 8b, 9, 12, 13, 21
Beetle (
Rhadine infernalis
)
1e1, 1e2, 2, 3, 4, 5, 6, 8a, 8b, 14, 15, 16, 17, 18, 19
Helotes mold beetle (
Batrisodes venyivi
)
1e1, 3, 5
Of the 74 caves known to contain one or more of the listed species, 43 were not included in the critical habitat designation. These 43 caves, and the reasons they were not designated, are described in the following summary.
Two caves, referred to as “unnamed cave
1/2
mile N of Helotes” and “5 miles NE of Helotes,” were not included in the proposed or final designation because their precise locations are unknown.
One cave, Crownridge Canyon Cave, was confirmed as a new location for one of the listed species during the public comment period. This cave was not included in this final determination because deadlines negotiated under the court-ordered settlement did not allow us to re-propose critical habitat, and thus there was not opportunity for the public to comment on its inclusion. Although we cannot include Crownridge Canyon Cave in this designation of critical habitat, we consider the cave and the associated karst ecosystem to be important to the conservation of the species. Because the cave is known to be occupied, it will receive protection under sections 7 (under the “jeopardy standard” standard), 9, and 10 of the Act.
Of the ten occupied caves associated with the La Cantera HCP, none were included in the proposed designation, and we have not included them in the final designation of critical habitat. We authorized two caves for take of
C. madla
under La Cantera's section 10(a)(1)(B) permit associated with the HCP. These two caves were heavily impacted as a result of authorized take and are not expected to contribute to the species' recovery. The other eight caves associated with the La Cantera HCP are protected within five karst management areas that will be perpetually managed and monitored in accordance with the conservation needs of the species. In most cases, these karst management areas were not considered adequate as stand alone preserves. Therefore, where appropriate, we included lands surrounding these occupied caves and associated management areas as part of the designation of critical habitat, as these lands provide physical and biological features that are essential to the conservation of the species. These areas include: Canyon Ranch Pit, Fat Man's Nightmare Cave, and Scenic Overlook Cave and the surrounding approximately 30 ha (75 ac); Helotes Blowhole and Helotes Hilltop caves and the surrounding approximately 10 ha (25 ac); John Wagner Ranch Cave No. 3 and the surrounding approximately 1.6 ha (4 ac); Hills and Dales Pit and the surrounding approximately 28 ha (70 ac); and Madla's Cave and the surrounding approximately 2 ha (5 ac). These eight caves and their associated karst management areas are being protected under the HCP, and we have not included them in this critical habitat designation (see “Lands Covered Under Existing Conservation Plans” section). Because of their geographic relationship to the rest of the critical habitat unit, it was difficult to show some of these areas in our mapping process. Thus, although some of these areas occur within the mapped area, they are not included in a legal sense through language in the final determination.
We did not include seven occupied caves in the Government Canyon State Natural Area (GCSNA), which is owned by the Texas Parks and Wildlife Department (TPWD), and 23 occupied caves on the Department of Defense's (DOD) Camp Bullis, in this critical habitat designation. Five of these caves were known to be occupied at the time of the proposed rule and were included in the proposed rule. The presence of listed species in the other two caves was confirmed by TPWD during the public comment period. During the public comment period, the Service received
and approved karst management plans submitted by each agency. These plans commit TPWD and DOD to long-term management and monitoring strategies that for the listed species and their habitat on their respective lands. The “Lands Covered Under Existing Conservation Plans” section explains the reasons why we did not include these areas in this designation of critical habitat.
Critical Habitat Unit Descriptions
Unless otherwise indicated in the unit descriptions below, each unit encompasses the following components: one or more occupied caves; the footprint of each cave; a 150 m (492 ft) area around the cave to encompass the cave cricket foraging area (50 m (164 ft)) and a buffer of 100 m (328 ft) against the effects of urban edges and red imported fire ant invasion; the surface and subsurface drainage areas associated with each cave as estimated in Veni (2002), to the extent possible; and, where possible, a minimum of 16 ha (40 ac) of surface vegetation encompassing each cave or cave cluster. Also, where possible, each unit was delineated to include contiguous deposits of Zone 1 karst-bearing rock as defined by Veni (2002) underlying the cave cricket foraging area plus buffer, the drainage areas, and the vegetative area.
As explained previously (
see
“Critical Habitat Delineation” section), some of the units include human-constructed, aboveground, impervious structures (e.g., buildings, paved roads) that do not contain the primary constituent elements and are not considered to be critical habitat. They are included within the mapped unit because subsurface areas under these structures are considered to be critical habitat, since subterranean spaces containing the karst species, or transmitting moisture and nutrients through the karst ecosystem, extend underneath these existing human-constructed structures. Within the units, landscaped areas associated with existing human-constructed structures also are not considered to be critical habitat because they do not contain the primary constituent elements, although they may provide some foraging area for cave crickets and other trogloxenes that are an important source of nutrients to the karst ecosystem.
Critical habitat boundaries are described as the area bounded by coordinates provided as geographic longitude and latitude coordinate pairs (e.g., -98.7612682, 29.4363049), referenced to North American Horizontal Datum 1983 (NAD 83). Coordinates were derived from 2001 digital orthophotographs obtained from the Bexar County Appraisal District. A description of each unit designated, including the current status of the lands in and around the unit, is presented below.
Unit 1e1
Unit 1e1 contains two occupied caves (Table 3). The surface of the unit consists primarily of undeveloped land. The majority of the unit is privately owned, with a small portion occurring on the City of San Antonio's Iron Horse Canyon tract, which was purchased under the Proposition 3 program. Proposition 3 is the Parks Development and Expansion Venue Project passed by San Antonio voters in 2000 for preservation of undeveloped Edwards Aquifer Recharge Zone lands. This unit is surrounded by undeveloped, privately owned land, including the City of San Antonio's Iron Horse Canyon tract and the La Cantera Canyon Ranch karst management area, which is being managed in perpetuity for the conservation of the species under a section 10(a)(1)(B) permit. (See “Lands Covered Under Existing Conservation Plans” section.) This unit contains all of the components described above, with the exception of a portion of the groundwater drainage area and cave cricket foraging area and buffer associated with San Antonio Ranch Pit extends onto La Cantera's Canyon Ranch karst management area, which is being managed for the conservation of the listed karst invertebrates.
Unit 1e2
Unit 1e2 contains one occupied cave (Table 3). The surface of the unit consists primarily of undeveloped lands with a few small roads. The entire unit occurs on the City of San Antonio's Iron Horse Canyon property. This unit contains all of the components described above.
Unit 1e3
Unit 1e3 contains two occupied caves (Table 3). The surface of the unit consists of undeveloped land with several small roads. The majority of the land is privately owned with a portion of the unit occurring on the City of San Antonio's Iron Horse Canyon property. This unit is surrounded by undeveloped, privately owned land, the City of San Antonio's Iron Horse Canyon property, and TPWD's Government Canyon State Natural Area. This unit contains all of the components described above, with the exception of a portion of the 21 ha (51 ac) subsurface drainage area shared by both caves that occurs on TPWD's Government Canyon State Natural Area, which we did not include in the designation (
see
“Lands Covered Under Existing Conservation Plans” section).
Unit 2
Two occupied caves occur within this Unit 2 (Table 3). The surface of Unit 2 consists of large, privatelyowned tracts, which appear to be primarily undeveloped with the exception of several small buildings and two or three small roads. The unit is surrounded by primarily undeveloped privately owned land. This unit contains all of the components described above, with the exception of a small portion of the 80-acre subsurface drainage basin associated with these caves that extends outside of the western boundary of this unit. This area was not included in this final determination because it was not identified in the proposed rule and therefore was not available for public comment. Although not included in the critical habitat area, minimizing impacts to the subsurface drainage area associated with these caves may be important for the conservation of the species in that cave.
Unit 3
Unit 3 consists of large tracts of primarily undeveloped privately owned land. La Cantera's Helotes Blowhole/Helotes Hilltop karst management area (approximately 10 ha (25 ac)) occurs entirely within this unit and contains two occupied caves (Table 3). This management area was acquired by La Cantera under their Section 10(a)(1)(B) permit, which requires that these caves and the surrounding lands be managed in perpetuity for the conservation of the species. We did not include these caves and associated management areas in the designation of critical habitat (see “Lands Covered Under Existing Conservation Plans” section). This unit was delineated to encompass the portion of the cave cricket foraging area plus buffer, the 16 ha (40 ac) vegetation area, and the subsurface drainage basin shared by the occupied caves that extends outside of the area protected under the La Cantera HCP. The majority of the unit overlies a contiguous deposit of Zone 1 karst-bearing rock and a small portion of Zone 3 as defined in Veni (2002), which underlies part of the cave cricket foraging area and buffer.
Unit 4
Unit 4 includes one occupied cave (Table 3). Lands surrounding Unit 4 consist of relatively large undeveloped tracts with some subdivided residential tracts that appear to be partially developed. The majority of the unit
overlies a contiguous deposit of Zone 1 karst-bearing rock with a small portion of Zone 3, which underlies part of the cave cricket foraging area and associated buffer areas. This unit contains all of the components described above.
Unit 5
Unit 5 contains one occupied cave (Table 3). The surface of Unit 5 consists of a large tract of privately owned, undeveloped land and several smaller tracts developed with homes and an associated residential road. The unit is bordered to the north and northwest by large tracts of undeveloped land and bordered on the remaining sides by smaller tracts with some residential development. This unit contains all of the components described above. The majority of the unit overlies a contiguous deposit of Zone 1 karst-bearing rock, with a small portion of Zone3, which underlies part of the cave cricket foraging area and associated buffer area.
Unit 6
La Cantera's John Wagner Ranch Cave #3 karst management area is within this unit, and contains one occupied cave (Table 3). This cave, and approximately 1.6 ha (4 ac) surrounding the cave, were acquired by La Cantera under their section 10(a)(1)(B) permit. The permit requires that the cave and the surrounding lands be managed in perpetuity for the conservation of the species. We did not include this cave, and the associated lands being managed under the permit, in this designation of critical habitat (see “Lands Covered Under Existing Conservation Plans” section). The surface of Unit 6 consists of several subdivided, large-lot tracts with homes and their associated roads and a large, undeveloped tract to the north owned by the City of San Antonio as part of the Thrift tract, which was purchased under the Proposition 3 program. The unit is surrounded on most of three sides by the City-owned Thrift tract and is adjacent to large-lot residential development to the south and southwest. This unit was delineated to encompass the portion of the cave cricket foraging area plus buffer, the subsurface drainage basin, and 16 ha (40 ac) vegetation area that extends outside of the area protected under the La Cantera HCP. The majority of Unit 6 overlies a contiguous deposit of Zone 1 karst-bearing rock with a small portion of Zone 3, which underlies part of the cave cricket foraging area and associated buffer area.
Unit 7
Unit 7 contains one occupied cave (Table 3). The surface of Unit 7 consists of relatively large, privately owned, undeveloped tracts with a few residential roads. The unit is surrounded by large, primarily undeveloped, privately-owned land. This unit contains all of the components described above.
Unit 8a
Unit 8a contains one occupied cave (Table 3). The surface of Unit 8a consists of large tracts of undeveloped land with a few small roads. About half of the unit is privately-owned. The other half lies within the City of San Antonio's Medallion tract, which was purchased under the Proposition 3 program. The unit is surrounded by undeveloped, privately owned lands and the City's Medallion property. This unit contains all of the components described above.
Unit 8b
Unit 8b contains two occupied caves (Table 3). The surface consists of large, primarily undeveloped tracts. A large portion of this unit occurs on the City of San Antonio's Medallion property, which was purchased under the Proposition 3 program. This unit also contains a portion of La Cantera's Hills and Dales Pit karst management area, which contains Hills and Dales Pit, one of the two occupied caves within the unit (Table 3). Hills and Dales Pit and 28 ha (70 ac) surrounding the cave were acquired by La Cantera under a section 10(a)(1)(B) permit, which requires that the cave and the surrounding lands be managed in perpetuity for the conservation of the species. We did not include this cave and associated lands in this designation of critical habitat (see “Lands Covered Under Existing Conservation Plans” section). This unit was delineated to encompass the portion of the 33-acre surface drainage basin and cave cricket foraging area plus buffer associated with Hills and Dales Pit that extends outside of the 28-ha management area protected under the La Cantera HCP, as well as all of the components associated with Robber's Cave as descri
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