Endangered and Threatened Wildlife and Plants; Determination of Threatened Status for the California Tiger Salamander; and Special Rule Exemption for Existing Routine Ranching Activities
We, the Fish and Wildlife Service (Service), determine threatened status for the California tiger salamander (Ambystoma californiense), under the Endangered Species Act of 1973, as amended (Act). The California tiger salamander, Central population is threatened by habitat destruction, degradation, and fragmentation due to urban development and conversion to intensive agriculture. We also finalize the 4(d) rule for the species rangewide, which exempts existing routine ranching activities.
Endangered and Threatened Wildlife and Plants; Listing Central California Distinct Population Segment of California Tiger Salamander as Threatened; Reclassifying Sonoma County and Santa Barbara County
5 actions from May 23rd, 2003 to May 2005
May 23rd, 2003
July 3rd, 2003
- NPRM Comment Period Extended
September 30th, 2003
- NPRM Comment Period Reopened
- NPRM Comment Period Reopened; Sonoma and Santa Barbara Counties' DPSs
- Final Action--Listing Central DPS
Table of Contents Back to Top
- FOR FURTHER INFORMATION CONTACT:
- SUPPLEMENTARY INFORMATION:
- Scientific Disagreement Over Availability of Central California Tiger Salamander Habitat Due to Past Conversions
- Future Conversions to Intensive Agriculture
- Description and Life History of the California Tiger Salamander
- Previous Federal Action
- Summary of Comments and Recommendations
- Peer Review
- Summary of Comments and Responses for the Proposed Downlisting of the Santa Barbara and Sonoma County Distinct Population Segments
- State Agencies
- Summary of Public Comments and Responses
- Issue 1—Distribution, Habitat, Threats, and Use of Science
- Issue 2. Listing Process
- Issue 3. Cost and Regulatory Burden
- Issue 4. Notification and Public Comment
- Issue 5. Property Rights
- Issue 6. Critical Habitat and Recovery Planning
- Issue 7. Designation and Listing Status of the Central California Tiger Salamander
- Issue 8. Proposed 4(d) Rule To Exempt Existing Routine Ranching Activities
- Issue 9. Basis for Proposing Threatened Status for Santa Barbara and Sonoma County Populations
- Issue 10. Discreteness and Significance of Santa Barbara and Sonoma Populations
- Summary of Factors Affecting the California Tiger Salamander
- A. The Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or Range
- Central Population
- Results of Service Analysis of Habitat
- Sonoma and Santa Barbara Populations
- Urban and Agricultural Land Uses
- Conclusion for Factor A
- B. Overutilization for Commercial, Recreational, Scientific, or Educational Purposes
- C. Disease or Predation
- D. The Inadequacy of Existing Regulatory Mechanisms
- E. Other Natural or Manmade Factors Affecting Its Continued Existence
- Rodent Control
- Mosquito Control
- Road-Crossing Mortality
- Hybridization With Non-native Salamanders
- Livestock Grazing
- Special Rule
- Routine Livestock Ranching Activities Exempted by the Special Rule
- Critical Habitat
- Available Conservation Measures
- National Environmental Policy Act
- Paperwork Reduction Act
- Executive Order 13211
- References Cited
- List of Subjects in 50 CFR Part 17
- Regulation Promulgation
- PART 17—[AMENDED]
DATES: Back to Top
This rule is effective September 3, 2004.
ADDRESSES: Back to Top
The complete file for this rule is available at U.S. Fish and Wildlife Service, Sacramento Fish and Wildlife Office (SFWO), 2800 Cottage Way, Suite W-2605, Sacramento, CA 95825.
FOR FURTHER INFORMATION CONTACT: Back to Top
Wayne White, Field Supervisor (Attn: CTS) telephone: 916/414-6600; facsimile: 916/414-6713.
SUPPLEMENTARY INFORMATION: Back to Top
Background Back to Top
We, the Fish and Wildlife Service (Service), determine threatened status for the California tiger salamander (Ambystoma californiense), under the Endangered Species Act of 1973, as amended (Act). We also finalize the 4(d) rule for the species rangewide.
We will also soon publish a proposed rule designating critical habitat for the Central California tiger salamander in 20 counties in California.
This rule satisfies the final portion of the settlement agreement approved by the Court on June 6, 2002, in Center for Biological Diversity v. U. S. Fish and Wildlife Service (No. C-02-055-WHA (N.D. Cal.). The settlement agreement required us, among other things, to submit a proposal to list the California tiger salamander throughout its remaining range in California (except for the Santa Barbara County and Sonoma County Distinct Population Segments) for publication in the Federal Register on or before May 15, 2003, and to submit a final determination on that proposed rule for publication in the Federal Register on or before May 15, 2004. Throughout this rule we will refer to the final population addressed by the settlement agreement as the Central California tiger salamander. References to the rangewide CTS population include the Sonoma and Santa Barbara populations as well as the Central population addressed in the settlement agreement.
On May 14, 2004, the Assistant Secretary for Fish and Wildlife and Parks at the U.S. Department of the Interior requested from the Court a six-month extension of the May 15, 2004, deadline pursuant to 16 U.S.C. 1533(b)(6)(B)(i). The request was based upon the Assistant Secretary's assessment that there is substantial disagreement regarding the sufficiency or accuracy of the available data relevant to the determination, including the level of threat due to inadequacy of the existing regulatory structure, projected future habitat losses and their significance, and the sufficiency or accuracy of data concerning extent of population losses and extent of existing populations. The Court granted an extension to July 23, 2004, to allow us time to resolve the issues raised by the information included in the preliminary California Department of Conservation's (CDC) 2004 data on rangeland and agricultural land conversion. This final listing determination has considered the implications of the information in the CDC report for the California tiger salamander. In addition, we have considered all other scientific and commercial information available to us.
Scientific Disagreement Over Availability of Central California Tiger Salamander Habitat Due to Past Conversions Back to Top
On June 10, 2004, the United States District Court for the Northern District of California granted an extension to the May 15, 2004, deadline for the specific purpose of resolving the issue of whether there was a 14 percent decrease in grazing land versus an increase in such land that would constitute an increase in Central California tiger salamander habitat. The Court also stated that the Service must make its final determination by July 23, 2004. The issue of habitat trend arose from an April 30, 2004, letter from the Central California Tiger Salamander Coalition (Coalition) to the Service stating that new information was available on the California Department of Conservation's (CDC) Farmland Mapping and Monitoring Program (FMMP) website. The Coalition stated that this new information indicated that grazing land increased by 1,678 ha (4,146 ac) from 2000 to 2002 for ten counties located within the range of the Central California tiger salamander. The Coalition proposed that these new grazing land areas would serve as habitat for the California tiger salamander, which would in turn offset the loss of salamander habitat that is being converted to intensive agriculture. In their letter, the Coalition concluded that the loss of Central California tiger salamander habitat to intensive agriculture was not a threat to the species.
In response to the July 23, 2004, extension, the Center for Biological Diversity (Center) sent a letter regarding the issue of grazing land and urbanization trends as determined by the FMMP data. In their letter, the Center provided information from the most recent reporting period (six counties, 2000 to 2002) and information on 13 counties that did not have 100 percent coverage from 1992 to 2002 (data from counties that had 100 percent coverage were presented in their comment letter dated September 22, 2003). From the most recent data (2000 to 2002), the Center determined that grazing land continued to be lost to development and other land use changes. This trend was also observed when the data were analyzed for all other counties that did not have 100 percent coverage. In their comment letter dated September 22, 2003, the Center also concluded that many other adverse indirect impacts to California tiger salamanders would result from the continued expansion of urbanization.
Thus, while the two groups used the same data from FMMP, they each applied different analyses and came up with different results and conclusions regarding the future threat to the Central California tiger salamander from the conversion of grazing land.
Following the June 10, 2004, hearing, representatives from the Service met with members of the Coalition and the Center on June 29, 2004, to receive clarification from the Coalition on the issue of trends in the acreage of grazing land. At this meeting, the Coalition provided the Service with a report entitled, “Evaluation of Threats to CTS from Agricultural Conversion.” This report provided additional information on changes in the acreage of grazing land to intensive agriculture using the FMMP data within their suggested range of the Central California tiger salamander. The Coalition's report also discussed the results of meetings with Agricultural Commissioners from six counties to discuss future conversion of grazing land to intensive agriculture within their respective counties.
After reviewing the information provided by the Coalition, the Center, and our own analysis, we found that all approaches comparing total grazing land lost to total grazing land gained for the 10- to 12-year period indicate a net loss of grazing land for that period. Comparing a different set of figures, however, it appears that intensively farmed lands have been fallowed at a greater rate than they have been reconverted over the last 12 years. It is more difficult to determine what this means to the California tiger salamander. It is unlikely that all of the grazing land converted to intensive agriculture was suitable for salamanders, as some of that could simply be reconversion of previously cultivated land, so the magnitude of the loss likely is not as large as the numbers indicate. Similarly, it is unlikely that the grazing land gained from fallowed agricultural land was all suitable for salamanders.
It is unlikely that the grazing lands formerly under intensive agricultural uses would completely regain all value as California tiger salamander habitat because wetlands that provide breeding habitat would have been destroyed as a result of intensive farming, limiting these areas to potential upland habitat. Fallowed agricultural land might, depending on how it is managed, provide estivation habitat or open space for migration depending on its proximity to breeding habitat. Even though the overall rate of conversion of new lands to intensive agriculture may be decreasing in the future (see below), any expansion of lands under cultivation is most likely to expand into areas adjacent to already cultivated areas. Particularly in the San Joaquin Valley, the lands at greatest risk to this expansion are the fringes of the valley floor which are inhabited by the California tiger salamander. Therefore, we conclude that the majority of these newly created grazing areas may have some utility for migration or estivation to the extent they are adjacent to breeding habitat, but that they do not offset the loss of the portion of grazing lands that were suitable California tiger salamander habitat. In addition, neither the Coalition nor the County Agricultural Commissioners concluded that no California tiger salamander habitat would be converted to intensive agricultural uses in the foreseeable future, only that the future rates of conversion are likely to be lower than they have been in the past. We therefore conclude while it may no longer be the primary source that conversion of suitable habitat to intensive agriculture remains a source of cumulative habitat loss and fragmentation which are primary threats to the California tiger salamander.
The FMMP is a valuable tool for assessing changes in land use over time. However, it is also important to use other sources of information when determining past habitat trends because of continued improvements in mapping technologies and the purpose of each reporting service. We found that grazing land has been lost due to urbanization, conversions to intensive agriculture, and other land uses. We expect these land use trends to continue largely due to the projected increase in human population and development, as well as subsequent expansion of intensive agriculture, as described in this rule.
The areas where acreage of grazing land increased represented 80,267 ha (198,344 ac) over the 10-year period on a county-wide basis. Approximately 60,926 ha (150,552 ac, 76 percent) of this increase is attributable to cultivated agricultural lands that were fallowed. The grazing land increases reported by FMMP are those lands that have been fallowed for at least three reporting periods or 6 years. Other grazing lands had been previously mapped and reported as urbanized areas, mines, or low-density residential developments, which accounted for 17,608 ha (43,511 ac, 22 percent) of the increase in grazing land. Many of these data, including much of the recent data available from FMMP (2000 to 2002), indicate that the increase in grazing land areas are due to improvements in digital imagery that allowed for a more precise distinction between urban boundaries and grazing land (CDC 2002, 2004).
The FMMP data indicate that there was a substantial decline in grazing land in areas, some of which likely represented aquatic and upland habitats for the California tiger salamander and some of which, such as reconverted fallowed agricultural lands, did not. Because of the lower quality of the habitat that may be created from fallowed land, it is unlikely that the increase in grazing land during the 1990s and early 2000s offset the decline in habitat that occurred as a result of the continued trend in grazing land converted to intensive agriculture and development.
Future Conversions to Intensive Agriculture Back to Top
Using the acreage of grazing land converted to intensive agriculture during this period, the Coalition estimated that 68,119 ha (168,325 ac) of grazing land would be converted to intensive agriculture over the next 25 years based on an estimated rate of loss of 2,725 ha (6,733 ac) per year. The Coalition estimated that this would result in a 4.1 percent loss (68,119 ha, 168,325 ac) of salamander habitat from their estimate of the total amount of available Central California tiger salamander habitat (1.7 million ha, 4.1 million ac). Responses by the Agricultural Commissioners to the interviews indicated that they believed that no more than 405 to 809 ha (1,000 to 2,000 ac) of grazing land would be converted in their counties and that the future loss of grazing land to intensive agriculture would be limited due to lack of water, poor soils, and low crop prices. The Agricultural Commissioners also expected that the majority of future expansions of intensive agriculture would occur around the periphery of other intensive agricultural areas.
Summary Back to Top
After reviewing data from the 2000-2002 FMMP report, and the supporting information submitted by the Center and the Coalition, we conclude that the newest data set is consistent with trends identified in our habitat analysis for approximately 1990 through 2000, showing that rates of habitat loss for California tiger salamander from all land use changes have been greater than the rate of other land use types “converting” to grazing land. We found that between 20 and 25 percent of the observed increase in grazing lands between 2000 and 2002 is attributable to better mapping technology. We also found that rates of agricultural land being fallowed have been greater than rates of fallowed lands being reconverted to cultivation or natural habitat being converted to intensive agricultural uses. We conclude that the majority of these newly created grazing areas may have some utility for migration or estivation, to the extent they are adjacent to breeding habitat, or even potential breeding habitat if stockponds are eventually installed, but they do not offset the loss of the portion of grazing lands that were suitable habitat for the California tiger salamander habitat; however, rates of habitat conversion to intensive agriculture are likely to be lower in the future than they have been in the past.
Description and Life History of the California Tiger Salamander Back to Top
Systematics and species description. The California tiger salamander was first described as Ambystoma californiense by Gray in 1853 based on specimens that had been collected in Monterey, California (Grinnell and Camp 1917). Storer (1925) and Bishop (1943) also considered the California tiger salamander to be a distinct species. Dunn (1940), Gehlbach (1967), and Frost (1985) believed the California tiger salamander was a subspecies of the more widespread tiger salamander (A. tigrinum). However, based on recent studies of the genetics, geographic distribution, and ecological differences among the members of the A. tigrinum complex, the California tiger salamander has been determined to represent a distinct species (Shaffer and Stanley 1991; Jones 1993; Shaffer et al. 1993; Shaffer and McKnight 1996; Irschick and Shaffer 1997; Petranka 1998). The range of this amphibian does not naturally overlap with any other species of tiger salamander (Stebbins 1985; Petranka 1998).
The California tiger salamander is a large and stocky terrestrial salamander with small eyes and a broad, rounded snout. Adults may reach a total length of 208 millimeters (mm) (8.2 inches (in)), with males generally averaging about 203 mm (8 in) in total length, and females averaging about 173 mm (6.8 in) in total length. For both sexes, the average snout-to-vent length is approximately 91 mm (3.6 in). The small eyes have black irises and protrude from the head. Coloration consists of white or pale yellow spots or bars on a black background on the back and sides. The belly varies from almost uniform white or pale yellow to a variegated pattern of white or pale yellow and black. Males can be distinguished from females, especially during the breeding season, by their swollen cloacae (a common chamber into which the intestinal, urinary, and reproductive canals discharge), larger tails, and larger overall size (Stebbins 1962; Loredo and Van Vuren 1996).
Distribution and genetics. California tiger salamander breeding and estivation habitat includes vernal pools, and seasonal and perennial ponds and surrounding upland areas in grassland and oak savannah plant communities from sea level to about 1,067 meters (m) (3,600 feet (ft)) (Stebbins 1989; Shaffer et al. 1993; Jennings and Hayes 1994; Petranka 1998; California Natural Diversity Data Base (CNDDB) 2003; Bobzien in litt. 2003; Service 2004). Along the Coast Ranges, the species occurs in the Santa Rosa area of Sonoma County, southern San Mateo County south to San Luis Obispo County, and the vicinity of northwestern Santa Barbara County (CNDDB 2003). In the Central Valley and surrounding Sierra Nevada foothills and Coast Range, the species occurs from northern Yolo County (Dunnigan) southward to northwestern Kern County and northern Tulare and Kings Counties (CNDDB 2003). This final rule lists the California tiger salamander rangewide as threatened including the Central California tiger salamander population as required by the court and the former DPSs located in Sonoma and Santa Barbara counties, which were listed as endangered (see Previous Federal Action section below) as well as the remaining population of the California tiger salamander as required by the court.
Other records of tiger salamanders from Lake and Mono Counties outside the range of the Central California tiger salamander have been identified as non-native tiger salamanders (Shaffer et al. 1993). Salamanders at Grass Lake in Siskiyou County (Mullen and Stebbins 1978) have been identified as the northwestern tiger salamander (A. t. melanostictum) (H.B. Shaffer, University of California, Davis pers. comm. 1998).
We note several historical occurrences of the salamander outside its current range. In the northeastern Sacramento Valley, there is a single occurrence located at the Gray Lodge Waterfowl Management Area in southern Butte County and northern Sutter County, and there is also a single occurrence located in Glenn County; both of these records are from the mid 1960s (CNDDB 2003). There are two records from 1939 and another, from an unknown date, of salamanders observed on the edge of the range in south western San Luis Obispo County (CNDDB 2003; Shaffer and Trenham 2004). There is also a historic record of the California tiger salamander that occurs outside the species' range, which is from Riverside County recorded in the late 1800s. Subsequent surveys have not been able to verify the presence of tiger salamanders from any of those locations (Stebbins 1989; Shaffer et al. 1993; M. Root, USFWS, pers. comm. 2004).
Although the area between Butte County and the Cosumnes River contains suitable vernal pools and has been surveyed extensively, the species has only been recorded along the southern edge of Sacramento County, south of the Cosumnes River (CNDDB 2003). In a survey transect that extended along the west side of the Sacramento Valley from Shasta County to Solano County, containing 35 kilometers (km) (22 miles (mi)) of vernal pool habitat and over 200 pools, California tiger salamanders were recorded only at the Jepson Prairie in Solano County (Simovich et al. 1993). In the East Bay area, the California tiger salamander generally does not occur west of Interstate Highway 680, south of Interstate Highway 580, or north of State Highway 4 in Contra Costa or Alameda Counties (LSA Associates, Inc. 2001; CNDDB 2003). It is likely that the species is uncommon or absent in much of the southernmost San Joaquin Valley because of unsuitable habitat. This includes areas to the south of Los Banos in Merced County, and the foothills of the Sierra Nevada south of Visalia in Tulare County (Shaffer et al. 1993).
The factors that restrict the California tiger salamander in the northern and southern extent of its range are not fully understood (H.B. Shaffer, pers. comm. 2002), but may include low rainfall in the southern San Joaquin Valley and the greater abundance of non-native predatory fish in the northern Sacramento Valley (Hayes 1977). Studies suggest that the present patchy distribution pattern was caused by a combination of the extreme anthropogenic changes in and around the Central Valley, and the restrictive breeding requirements of the species (Dahl 1990; Fisher and Shaffer 1995; Frayer et al. 1989; Holland 1978, 1998; Jones and Stokes 1987; Shaffer et al. 1993; Trenham et al. 2000). Because there are only a few historic collections of the species made during the 1800s, and the majority of collections have occurred in the last 25 years (CNDDB 2003) subsequent to significant changes in historic habitat types (Shaffer et al. 1993), we do not have good documentation of the historic distribution of the California tiger salamander. We have based the analysis in this listing on estimated current distribution and habitat availability and assumed the available habitat is populated.
Reproduction and larval growth. Adult California tiger salamanders mate in vernal pools and similar water bodies, and the females lay their eggs in the water (Twitty 1941; Shaffer et al. 1993; Petranka 1998). In the East Bay area, California tiger salamanders may lay eggs twice, once in December and the second time in February (Bobzien in litt. 2003). Females attach their eggs singly or, in rare circumstances, in groups of two to four, to twigs, grass stems, vegetation, or debris (Storer 1925; Twitty 1941). In ponds with little or no vegetation, females may attach eggs to objects, such as rocks and boards on the bottom (Jennings and Hayes 1994). After breeding, adults leave the pool and return to small mammal burrows in surrounding uplands (Loredo et al. 1996; Trenham 1998a), although they may continue to come out nightly for approximately the next two weeks to feed (Shaffer et al. 1993). In drought years, the seasonal pools may not form and the adults may not breed (Barry and Shaffer 1994).
The eggs hatch in 10 to 14 days with newly hatched salamanders (larvae) ranging in size from 11.5 to 14.2 mm (0.5 to 0.6 in) in total length (Petranka 1998). The larvae are aquatic. Each is yellowish gray in color and has a broad fat head, large, feathery external gills, and broad dorsal fins that extend well onto its back. The larvae feed on zooplankton, small crustaceans, and aquatic insects for about six weeks after hatching, after which they switch to larger prey (J. Anderson 1968). Larger larvae have been known to consume smaller tadpoles of Pacific treefrogs (Pseudacris regilla) and California red-legged frogs (Rana aurora) (J. Anderson 1968). The larvae are among the top aquatic predators in the seasonal pool ecosystems. They often rest on the bottom in shallow water, but also may be found at different layers in the water column in deeper water. The young salamanders are wary; when approached by potential predators, they will dart into vegetation on the bottom of the pool (Storer 1925).
The larval stage of the California tiger salamander usually lasts three to six months, because most seasonal ponds and pools dry up during the summer (Petranka 1998), although some larvae in Contra Costa and Alameda Counties may remain in their breeding sites over the summer (Alvarez in litt. 2003; Bobzien in litt. 2003; Shaffer and Trenham 2004). The absence of sexually mature paedomorphic larvae (mature adults that retain larval characteristics) suggests that the California tiger salamander is unable to express this life history trait, presumably because most of their evolutionary history has been spent in seasonal vernal pool habitats (Shaffer and Trenham 2004).
Amphibian larvae must grow to a critical minimum body size before they can metamorphose (change into a different physical form) to the terrestrial stage (Wilbur and Collins 1973). Larvae collected near Stockton in the Central Valley during April varied from 47 to 58 mm (1.9 to 2.3 in) in length (Storer 1925). Feaver (1971) found that larvae metamorphosed and left the breeding pools 60 to 94 days after the eggs had been laid, with larvae developing faster in smaller, more rapidly drying pools. The longer the inundation period, the larger the larvae and metamorphosed juveniles are able to grow, and the more likely they are to survive and reproduce (Semlitsch et al. 1988; Pechmann et al. 1989; Morey 1998; Trenham 1998b). The larvae perish if a site dries before they complete metamorphosis (P. Anderson 1968; Feaver 1971). Pechmann et al. (1989) found a strong positive correlation between inundation period and total number of metamorphosing juvenile amphibians, including tiger salamanders. In Madera County, Feaver (1971) found that only 11 of 30 pools sampled supported larval California tiger salamanders, and five of these dried before metamorphosis could occur. Therefore, out of the original 30 pools, only six (20 percent) provided suitable conditions for successful reproduction that year. Size at metamorphosis is positively correlated with stored body fat and survival of juvenile amphibians, and negatively correlated with age at first reproduction (Semlitsch et al. 1988; Scott 1994; Morey 1998).
Lifetime reproductive success for California and other tiger salamanders is low. Trenham et al. (2000) found the average female bred 1.4 times and produced 8.5 young that survived to metamorphosis per reproductive effort. This resulted in roughly 11 metamorphic offspring over the lifetime of a female. Most California tiger salamanders in this study did not reach sexual maturity until four or five years old (Trenham et al. 2000). While individuals may survive for more than 10 years, many breed only once, and one study estimated that less than five percent of metamorphic juveniles survive to become breeding adults (Trenham 1998b). The mechanisms for recruitment are clearly dependent on a number of factors such as migration, terrestrial survival, and population turnover, whose interaction is not well understood (Trenham 1998b).
Breeding habitat. The salamanders breeding in, and living around, a seasonal or perennial pool or pond and associated uplands utilized during the dry months are said to occupy a breeding site. A breeding site is defined as a location where the animals are able to successfully breed in years of normal rainfall and survive during the dry months of the year. The primary historic breeding sites used by California tiger salamanders included vernal pools and other natural seasonal ponds (Storer 1925; Feaver 1971; Zeiner et al. 1988; Trenham et al. 2000). The species has been found in 10 of the 17 California vernal pool regions defined by Keeler-Wolf et al. (1998). Vernal pools are an important part of the California tiger salamander breeding habitat in the Central Valley and South San Joaquin regions (CNDDB 2003). Currently, the salamander primarily uses stock ponds in the Bay Area and Coast Range regions, largely due to the destruction of vernal pool habitat in these regions. A number of records in the Santa Rosa area document CTS being found in ditches. The extent of the contribution of these intermittent water bodies has not been specifically studied, however there is no evidence that these areas are used for breeding (Cook in. litt. 2003).
Vernal pools typically form in topographic depressions underlain by an impervious layer (such as claypan, hardpan, or volcanic strata) that prevents downward percolation of water. Vernal pool hydrology is characterized by inundation of water during the late fall, winter, and spring, followed by complete desiccation during the summer dry season (Holland and Jain 1998). Vernal pools support diverse flora and fauna that are adapted to the dramatic seasonal changes in moisture and benefit from the lack of predation by non-native fish. Twenty-nine other federally or State listed species within the California tiger salamander's range are vernal pool specialists, including 24 plants, four crustaceans, and one insect (Keeler-Wolf et al. 1998). California tiger salamanders, like the listed vernal pool crustaceans, inhabit these seasonally inundated habitats. However, listed vernal pool crustaceans require a relatively short period of inundation to complete their life cycle (59 FR 48136; September 19, 1994); therefore, pools that support some crustaceans may not hold water long enough to allow successful metamorphosis of California tiger salamander larvae. In a study of amphibians located in eastern Merced County, California tiger salamander larvae were only observed in the largest vernal pools (Laabs et al. 2001). Unlike vernal pool crustaceans, California tiger salamanders can breed and metamorphose in perennial ponds.
In addition to vernal pools and seasonal ponds, California tiger salamanders also use small artificial water bodies such as stockponds for breeding (Stebbins 1985; Zeiner et al. 1988; Shaffer et al. 1993; Alvarez in litt. 2003; Bobzien in litt. 2003; CNDDB 2003). Stock ponds for cattle, sheep, horses, and other livestock have been, and continue to be, built to supply local water needs, especially in rural grazing lands in coastal and Sierra foothill areas where inexpensive public water or ground water is not available (Bennett 1970). Stock ponds constructed as water sources for livestock are important habitats for the California tiger salamander throughout its range (H. Shaffer, pers. comm. 2003; P. Trenham, University of California, Davis, pers. comm. 2002). In some areas, stock ponds have largely replaced vernal pools as breeding pools (due to the loss of vernal pools) and provide important habitat for the species. For instance, of the 155 California tiger salamander locality records in the East Bay area (Alameda and Contra Costa Counties) where the wetland type was identified, 85 percent (131 sites) were located in stock ponds (CNDDB 2003).
Management of stock ponds determines their suitability as breeding habitat for California tiger salamanders (Shaffer in litt. 2003). As is true of natural vernal pools, the inundation period of stock ponds can be so short that larvae cannot metamorphose (e.g., when early drawdown of irrigation ponds occurs). However, in contrast to natural vernal pools, stock ponds may contain water throughout the year, or for sufficiently long periods, that predatory fish and bullfrogs (R. catesbeiana) can colonize the pond and establish self-sustaining breeding populations (see Factor C below; Shaffer et al. 1993; Seymour and Westphal 1994) these populations likely affect California tiger salamanders. The presence of bull frogs and fish are negatively correlated with salamander populations and so it is possible that extirpation of the salamander population is likely if fish and other predators are introduced (Shaffer et al. 1993; Seymour and Westphal 1994). Inappropriate management of ponds can threaten California tiger salamander habitat. Natural soil erosion, sometimes increased by pond breaching, berm failure, stock animal impacts, and inadequate management practices can result in increased sedimentation of the pond (Hamilton and Jepson 1940, Prunuske 1987), thereby reducing their quality as salamander habitat. Alternatively, ponds with insufficient turbidity provide inadequate cover for larvae. Stock ponds may be geographically isolated from other seasonal wetlands occupied by California tiger salamanders, and newly created ponds may be located beyond the maximum dispersal distances of juvenile or adult salamanders. However, because the species can live for more than a decade (Trenham et al. 2000), and during this time individuals can migrate between aquatic and upland habitats, colonization of newly created and geographically isolated ponds may be possible, provided the intervening habitat can be successfully traversed by dispersing salamanders (Sweet in litt. 2003).
Once fall or winter rains begin, adults emerge from the upland sites on rainy nights to feed and to migrate to the breeding ponds (Stebbins 1985, 1989; Shaffer et al. 1993). Males migrate to the breeding ponds before females (Twitty 1941; Shaffer et al. 1993; Loredo and Van Vuren 1996; Trenham 1998b). Males usually remain in the ponds for an average of about six to eight weeks, while females stay for approximately one to two weeks. In dry years, both sexes may stay for shorter periods (Loredo and Van Vuren 1996; Trenham 1998b). Most marked salamanders have been recaptured at the pond where they were initially captured; in one study, approximately 80 percent were recaptured at the same pond over the course of three breeding seasons (Trenham 1998b). The rate of natural movement of salamanders among breeding sites depends on the distance between the ponds or complexes of ponds and on the quality of intervening habitat (e.g., salamanders may move more quickly through sparsely covered and open grassland than they can through densely vegetated lands) (Trenham 1998a).
Upland habitat and terrestrial ecology. California tiger salamanders spend the majority of their lives in upland habitats, and cannot persist without them (Trenham and Shaffer in review). The upland component of California tiger salamander habitat typically consists of grassland savannah (Shaffer et al. 1993; Alvarez in litt. 2003; Bobzien in litt. 2003; Service 2004). However, in Santa Barbara and eastern Contra Costa Counties, some California tiger salamander breeding ponds occur in grasslands with scattered oak trees, and scrub or chaparral habitats (Shaffer et al. 1993; Alvarez in litt. 2003; 65 FR 57242). Salamanders most commonly utilize burrows in open grassland or under isolated oaks, and less commonly in oak woodlands (Shaffer et al. 1993).
Juvenile and adult California tiger salamanders spend the dry summer and fall months of the year in the burrows of small mammals, such as California ground squirrels (Spermophilus beecheyi) and Botta's pocket gopher (Thomomys bottae) (Storer 1925; Loredo and Van Vuren 1996; Petranka 1998; Trenham 1998a). Although the upland burrows inhabited by California tiger salamanders have often been referred to as “aestivation” sites, which implies a state of inactivity, evidence suggests that California tiger salamanders may remain active in their underground dwellings (Sweet in litt. 2003). Movement within and among burrow systems continues for at least several months after the salamander leaves the breeding site (Trenham 2001; Trenham and Shaffer 2004).
California tiger salamanders cannot dig their own burrows, and as a result their presence is associated with burrowing mammals such as ground squirrels (Seymour and Westphal 1994). The creation of burrow habitat by ground squirrels and utilized by California tiger salamanders suggests a commensal relationship between the two species (Loredo et al. 1996). Active ground-burrowing rodent populations probably are required to sustain California tiger salamanders because inactive burrow systems become progressively unsuitable over time. Loredo et al. (1996) found that California ground squirrel burrow systems collapsed within 18 months following abandonment by, or loss of, the mammals. California tiger salamanders use both occupied and unoccupied burrows.
Adult California tiger salamanders have been observed up to 2,092 m (1.3 mi) from breeding ponds (S. Sweet, University of California, Santa Barbara, in litt. 1998), which may be vernal pools, stock ponds, or other seasonal or perennial water bodies. A recent trapping effort in Contra Costa County captured California tiger salamanders 805 m (2,641 ft) to 1,207 m (3,960 ft) from the nearest breeding aquatic habitat (Orloff in litt. 2003). Trenham et al. (2001) observed California tiger salamanders moving up to 670 m (2,200 ft) between breeding ponds in Monterey County. Similarly, in an experimental study, Shaffer and Trenham (in review) found that 95 percent of California tiger salamanders resided within 640 m (2,100 ft) of their breeding pond at Jepson Prairie in Solano County. Based on the Monterey County study, and with the caution that there is limited understanding as regards essential terrestrial habitats and buffer requirements, Trenham et al. (2001) recommended that plans to maintain local populations of California tiger salamanders should include pond(s) surrounded by at least 173-m (567-ft) wide buffers of terrestrial habitat occupied by burrowing mammals. The distance between the upland and breeding sites depends on local topography and vegetation, and the distribution of California ground squirrel or other rodent burrows (Stebbins 1989).
Metamorphosed juveniles leave the breeding sites in the late spring or early summer. Before the breeding sites dry completely, the animals settle in small mammal burrows, to which they return at the end of nightly movements (Zeiner et al. 1988; Shaffer et al. 1993; Loredo et al. 1996). Like the adults, juveniles may emerge from these retreats to feed during nights of high relative humidity (Storer 1925; Shaffer et al. 1993) before settling in their selected upland sites for the dry, hot summer months. Juveniles have been observed to migrate up to 1.6 km (1 mi) from breeding pools to upland areas (Austin and Shaffer 1992).
While most California tiger salamanders rely on rodent burrows for shelter, some individuals may utilize soil crevices as temporary shelter during upland migrations (Lorendo et al. 1996). Mortality of juveniles during their first summer exceeds 50 percent (Trenham 1998b). Emergence from upland habitat in hot, dry weather occasionally results in mass mortality of juveniles (Holland et al. 1990). Juveniles do not typically return to the breeding pools until they reach sexual maturity at two years of age at a minimum (Trenham 1998b; Hunt 1998), and survival to adulthood may be low. Trenham (1998b) estimated survival from metamorphosis to maturity at a site in Monterey County to be less than 5 percent (well below an estimated replacement level of 18 percent). Adult survivorship varies greatly between years, but is a crucial determinant of whether a locality is a source or sink (i.e., whether net productivity exceeds, or fails to reach, the level necessary to maintain the breeding site).
Metapopulation biology may help us predict the effects of future habitat loss and fragmentation for taxa that have a metapopulation structure (Marsh and Trenham 2001 and references cited therein). A metapopulation is a set of local subpopulations within an area, where subpopulations become extinct and are recolonized in the future by migrants from other subpopulations (Hanski and Gilpin 1991; Hanski 1994; McCullough 1996). Regional persistence in such systems depends on the migration of individuals between habitat patches (Trenham 1998b). California tiger salamanders appear to conform to a broadly defined metapopulation structure. In the California tiger salamander system, the spatial arrangement of ponds and the migratory behavior of the animals probably have a substantial influence on pond occupancy and local population persistence (Trenham 1998b). If metapopulation theory is predictive of California tiger salamander behavior, then the direct loss of breeding sites with high production of California tiger salamanders or their isolation from other sites due to habitat fragmentation could result in the loss of other breeding sites that rely on inter-pond dispersal or the metapopulation structure (Trenham 1998b; Marsh and Trenham 2001).
Number of individuals. The total number of individual California tiger salamanders rangewide is not known. Estimating the total number of California tiger salamanders is difficult due to limited data and understanding concerning the life history of the species. Data on numbers of individual California tiger salamanders are lacking for several reasons, first because the species is difficult to detect, second, because the animals spend much of their lives underground (Storer 1925, Feaver 1971, Shaffer et al. 1993, van Hattem 2004), and third, because only a portion of the total number of California tiger salamanders migrate to pools to breed each year (Trenham et al. 2000). The activity of California tiger salamanders during the majority of the year in these burrows is not well documented and has only recently been studied (van Hattem 2004). In the absence of estimates of the total number of California tiger salamanders, we primarily rely on measures of habitat availability as well as current and future habitat status as an indication of the status of the species.
Previous Federal Action Back to Top
On September 18, 1985, we published the Vertebrate Notice of Review (NOR) (50 FR 37958), which included the California tiger salamander as a category 2 candidate species for possible future listing as threatened or endangered. Category 2 candidates were those taxa for which information contained in our files indicated that listing may be appropriate but for which additional data were needed to support a listing proposal. The January 6, 1989, and November 21, 1991, candidate NORs (54 FR 554 and 56 FR 58804, respectively) also included the California tiger salamander as a category 2 candidate, soliciting information on the status of the species.
On February 21, 1992, we received a petition from Dr. H. Bradley Shaffer of the University of California at Davis, to list the California tiger salamander as an endangered species. We published a 90-day petition finding on November 19, 1992 (57 FR 54545), concluding that the petition presented substantial information indicating that listing may be warranted. On April 18, 1994, we published a 12-month petition finding (59 FR 18353) that the listing of the California tiger salamander was warranted but precluded by higher priority listing actions. We elevated the species to category 1 status at that time, which was reflected in the November 15, 1994, Animal NOR (59 FR 58982). Category 1 candidates were those taxa for which we had on file sufficient information on biological vulnerability and threats to support preparation of listing proposals. In a memorandum dated November 3, 1994, from the acting Assistant Regional Director of the Pacific Region to the Field Supervisor of the Sacramento Field Office, the recycled 12-month finding on the petition and a proposed rule to list the species under the Act were given a due date of December 15, 1995. However, on April 10, 1995, Public Law 104-6 imposed a moratorium on listings and critical habitat designations and rescinded $1.5 million funding from our listing program. The moratorium was lifted and listing funding was restored through passage of the Omnibus Budget Reconciliation Act on April 26, 1996. In the NOR published February 28, 1996 (61 FR 7596), we discontinued the use of different categories of candidates, and defined “candidate species” as those meeting the definition of former category 1. We maintained California tiger salamander as a candidate species in that NOR, as well as in subsequent NORs published on September 19, 1997 (62 FR 49398), October 25, 1999 (64 FR 57534) and October 30, 2001 (66 FR 54808).
On January 19, 2000, the Santa Barbara County DPS of the California tiger salamander was listed as an endangered species under an emergency basis (65 FR 3096) and proposed for listing as endangered (65 FR 3110). On September 21, 2000, we listed the Santa Barbara County DPS of the California tiger salamander as endangered (65 FR 57242). On January 22, 2004, we proposed critical habitat for the Santa Barbara County DPS (69 FR 3064).
On February 27, 2002, the Center for Biological Diversity (CBD) filed a complaint in the Northern District of California for our failure to list the Sonoma County Distinct Population Segment of the California tiger salamander as endangered (Center for Biological Diversity v. U.S. Fish and Wildlife Service (No. C-02-055-WHA (N.D. Cal.)). On June 6, 2002, the Court approved a settlement agreement requiring us to (1) make 90-day and 12-month petition findings on the Sonoma County DPS of California tiger salamander, or to publish an emergency and proposed rules if the DPS faced an emergency under the meaning of the Act's section 4(b)(7), by July 15, 2002 and (2) submit a proposal to list the California tiger salamander throughout its remaining range in California (except for the Santa Barbara County and Sonoma County Distinct Population Segments) for publication in the Federal Register on or before May 15, 2003, and to submit a final rule for publication in the Federal Register on or before May 15, 2004. On July 22, 2002, we listed the Sonoma County DPS of the California tiger salamander as an endangered species on an emergency basis and proposed to list the DPS as endangered permanently (67 FR 47726; 67 FR 47758). On March 19, 2003, we listed the Sonoma County DPS of the California tiger salamander as endangered (68 FR 13498) with notice that the Service would consider downlisting or listing the entire species rangewide. On May 23, 2003, we proposed (1) to list the Central California DPS of the California tiger salamander as threatened, (2) to downlist the Santa Barbara and Sonoma DPSs from endangered to threatened, and (3) a 4(d) rule for the California tiger salamander where listed as threatened (68 FR 28648). We also asked for public comment on a number of issues, including whether the three populations should be consolidated into a single rangewide listing. This final rule completes our obligations under the settlement agreement.
Summary of Comments and Recommendations Back to Top
In the May 23, 2003, proposed rule, we proposed to list the Central California DPS of the California tiger salamander as threatened, and we proposed reclassification of the Santa Barbara County and Sonoma County populations from endangered to threatened (68 FR 28648). In the same notice we also proposed that the special rule under section 4(d) of the Act for the Central California DPS be extended to the Santa Barbara and Sonoma County DPS.
In the proposed rule and associated notifications, we announced six public hearings and requested that all interested parties submit factual reports or information that might contribute to the development of this final rule. The comment period for the proposed rule was initially open from May 23 through July 22, 2003. On July 3, 2003, we extended the comment period for an additional 60 days until September 22, 2003 (68 FR 39892) to accommodate additional public hearings. On September 30, 2003, we reopened the comment period for 30 days until October 31, 2003 (68 FR 56251).
We held a total of 10 public hearings on our May 23, 2003, proposed rule: two on June 17, 2003, in Livermore, California; two on June 18, 2003, in Monterey, California; two on June 19, 2003, in Merced, California; two on July 29, 2003, in Santa Rosa, California; and two on July 31, 2003, in Santa Maria, California. We also organized six informal workshops to inform the public and answer questions regarding the California tiger salamander and the proposed rule: two on June 10, 2003, in Livermore, California; two on June 11, 2003, in Merced, California; and two on June 12, 2003, in Monterey, California. On June 24, 2003, per the request of the Alameda County Agricultural Commission, we attended a county meeting, gave a presentation to the public on the proposed rule, and answered questions regarding the species and the proposal. In addition to the public hearings and public workshops we organized, we attended community forums in Merced, California, on September 12, 2003, and in Modesto, California, on October 24, 2003, to discuss the proposed rule and answer questions. At the forums, we provided information on where to obtain copies of the proposed rule and maps of the areas considered potential habitat for the species.
We produced news releases on the proposed listing and the public hearings and workshops and distributed them to the news media on May 16, 2003, July 3, 2003, and September 30, 2003. Stories based on the news releases and the meetings were produced by the Associated Press (May 16 and October 1); the Santa Rosa Press Democrat (May 18, July 30); the San Francisco Chronicle (May 17); the Santa Barbara News Press (May 17); the Modesto Bee (June 12); the Merced Sun-Star (June 12 and June 20), and the Stockton Record (June 18).
Written public comments were accepted at all the public hearings, workshops, and the Merced and Modesto meetings and entered into the supporting record for the rulemaking. Oral comments given at the public hearings were also accepted into the supporting record. In making our decision on the proposed rules, written comments were given the same weight as oral comments presented at hearings.
We contacted all appropriate State and Federal agencies, county governments, elected officials, and other interested parties and invited them to comment. This was accomplished through telephone calls, electronic mail correspondence, letters, and news releases faxed and/or mailed to appropriate elected officials, media outlets, local jurisdictions, interest groups, and other interested individuals. We also posted the proposed rule and associated material on both our Sacramento and Ventura Fish and Wildlife Office internet sites following their release on May 16, 2003, July 3, 2003, and September 30, 2003, respectively. We published legal notices on the public hearings and workshops in the Contra Costa Times and Tri-Valley Herald on June 1, 2003; the Merced Sun-Star, Monterey Herald, Santa Barbara News-Press, San Luis Obispo Telegram Tribune, and Salinas Californian on June 2, 2003; the Pinnacle Newspaper on June 5, 2003; and in the Santa Rosa Press Democrat on July 19, 2003.
We received a total of 1,955 comment letters and electronic mail correspondences (e-mails) during the three comment periods. Comments were received from Federal, State, and local agencies, Federal and State lawmakers, and private organizations and individuals. We reviewed all comments received for substantive issues and comments, and new information regarding the Central California tiger salamander, the proposed special rule to exempt routine ranching activities, the proposed downlisting of Santa Barbara County and Sonoma County DPSs, and on the appropriateness of a single rangewide designation or combinations of designations. Similar comments were grouped into several general issue categories relating specifically to the proposed rule and are identified below. Some of the comments expressed support for a listing of the Central California tiger salamander. Others opposed a listing. Substantive information supporting each position was incorporated into this final rule. All comments on the proposed reclassification of the Santa Barbara County and Sonoma County DPSs are addressed in this final determination.
Peer Review Back to Top
We asked 28 scientists, researchers, and biologists who have knowledge of California tiger salamanders, or amphibians generally, to provide peer review of the proposed rule. Eleven of the 28 individuals who were asked to act as peer reviewers submitted comments on the proposed rulemaking. Based on our analysis, all 11 peer reviewers supported the listing of the Central California tiger salamander as threatened. Two of the peer reviewers stated that the proposed exemption for routine ranching activities as written in the proposed rule lacked sufficient biological rationale or did not provide a conservation benefit to the California tiger salamander and stated that it is inappropriate to consider applying it to the Sonoma and Santa Barbara DPSs, while six were generally in support of the proposed 4(d) rule. Some peer reviewers suggested ways to improve the conservation aspects of this proposed exemption. Additionally, peer reviewers provided additional documentation of threats to the species and potential conservation measures. This information has been incorporated into the final rule.
Because we relied on unpublished genetics studies for this rule, we also requested peer review from nine universities on the mitochondrial DNA (mtDNA) study of California tiger salamander conducted by Dr. H.B. Shaffer and Dr. P.C. Trenham of the University of California at Davis (report cited as Shaffer and Trenham 2002). Three of the nine agreed to review the report. The peer reviewers had a few technical comments and suggestions; however, all three concluded that the methods and analyses used in this genetic research were appropriate and felt that the conclusions drawn by Dr. Shaffer and Dr. Trenham were appropriate and defensible. One of the peer reviewers also concluded that the data demonstrated that California tiger salamander hybridization with non-native tiger salamanders posed a considerable threat to the species. The study by Shaffer and Trenham has recently been accepted for publication (Shaffer et al. in press).
Summary of Comments and Responses for the Proposed Downlisting of the Santa Barbara and Sonoma County Distinct Population Segments Back to Top
Eight of the 11 peer reviewers who submitted comments on the proposed rule specifically addressed the proposed reclassification of the Santa Barbara and Sonoma County DPSs. Several stated that the proposed reclassification was not consistent with available information on the status and threats to the Santa Barbara and Sonoma County DPSs. One peer reviewer stated that, although it appeared counter-intuitive to change the listing designation without data showing some improvement in status, the reclassification may be warranted if the change would allow routine ranching activities.
State Agencies Back to Top
We received comments from the California Department of Food and Agriculture (CDFA). The issues raised by CDFA are addressed below.
CDFA Comment 1: The proposed rule to list the Central California tiger salamander should include a full discussion of the potential economic impacts associated with the proposed rule. The proposed listing will likely create a regulatory burden for landowners who convert rangeland to other forms of agriculture. Economic burdens to landowners need to be evaluated and mitigated.
Our Response: Under section 4(b)(1)(A) of the Endangered Species Act of 1973, as amended (Act) (16 U.S.C. 1531 et seq.), we must base a listing decision solely on the best scientific and commercial data available regarding the likelihood that the species meets the definitions of threatened or endangered as defined in the Act.
CDFA Comment 2: The relative importance of stressors to the Central California tiger salamander should be described.
Our Response: As described in more detail below, the California tiger salamander is at risk due to: (1) Habitat loss, degradation, and modification from land conversion and alteration; and secondarily to: (2) predation from non-native species; (3) inadequacy of existing regulatory mechanisms; and (4) hybridization with non-native tiger salamanders. Thus, the California tiger salamander is appropriately considered to be threatened by conditions identified under four of the five factors and meets the definitions of threatened, regardless of having a relatively extensive distribution. The threat of hybridization with non-native tiger salamanders is a particularly severe threat in the Central Coast Range and Bay Area regions and, to a lesser extent, the Central Valley region. We consider the other threats to be secondary, but still material to the status of the DPS (see Factor E below).
CDFA Comment 3: References in the proposed rule used to describe adverse impacts to the salamander need to be documented. CDFA indicated that it has recently completed a risk assessment of the use of rodenticides on threatened and endangered species.
Our Response: As stated in the proposed rule, the complete file for the rule is available for inspection, by appointment, during normal business hours at the Sacramento Fish and Wildlife Office. In addition, the proposed rule stated that all comments received during the comment period were available for public review. The complete file for this rule is available for inspection, by appointment, during normal business hours at the Sacramento Fish and Wildlife Office.
The Service received a copy of the risk assessment entitled, “Ecological Risk Assessment for Grain-Based Field-Use Anticoagulant Rodenticides Registered by the California Department of Food and Agriculture for Special Local Needs” (Silberhorn et al. 2003). The study was an ecological risk assessment that focused on four specific anticoagulant rodenticides and their potential for effects to non-target birds and mammals through secondary poisoning (e.g., poisoning through consumption of prey killed by the toxin). The primary target species for these rodenticides is the California ground squirrel, with mortality of exposed squirrels caused by internal hemorrhaging. Secondary poisoning of non-target species, such as canids or raptors, may result from preying on moribund animals or scavenging on carcasses. The ecological risk assessment did not examine potential effects to amphibians, and California tiger salamanders do not consume dead or dying rodents. The Service has determined that the results of this ecological risk assessment provide little information on the potential risk to California tiger salamanders as the result of direct or indirect effects of rodenticide use.
Summary of Public Comments and Responses Back to Top
We address other substantive comments and accompanying information in the following summary. Many of the public comments on the proposed downlisting of the Santa Barbara and Sonoma DPSs were similar to, and are included in, the summary of public comments and responses for the Central DPS. In addition to those, commenters raised the issues described below regarding the proposed reclassification of the Santa Barbara and Sonoma County DPSs. All substantive information provided by commenters has been evaluated in the process of making this final determination and has been incorporated into the final rule as appropriate.
Issue 1—Distribution, Habitat, Threats, and Use of Science
Comment 1: Numerous commenters stated that the Central California tiger salamander should not be listed as threatened or endangered because the Central California tiger salamander inhabits a large geographical area or is found in many counties. A few commenters, including local governments, stated that the proposed rule did not present scientific evidence that the Central California tiger salamander was threatened, or likely to become endangered in the foreseeable future, as defined by the Act. One commenter questioned how the Central California tiger salamander could be listed if a large portion of its habitat could be deemed as having beneficial land use practices (ranching activities) and these activities were proposed for exemption under the special 4(d) rule.
Our Response: A wide distribution or one that includes a number of counties does not, in and of itself, preclude the need to list a species, subspecies, or DPS under the Act. When making a listing determination, we carefully consider the best available scientific and commercial information regarding the historic and current ranges of the taxon under consideration, as well as the abundance of the species, and the pattern, imminence, and magnitude of threats relative to the species' distribution. After completing such an analysis for the Central California tiger salamander, we believe that the best available evidence supports a threatened listing. All 11 of the peer reviewers who responded agreed with our assessment.
We believe that one of the primary threats to the Central California tiger salamander is habitat destruction, degradation, and fragmentation. Much of this threat is related to losses of habitat to urban development and conversion to intensive agriculture. We believe routine ranching, as identified in the 4(d) rule, is neutral or beneficial for salamanders. Listing the DPS as threatened, while exempting these ranching practices, concurrently increases protection of rangelands from conversion to land uses which eliminate Central California tiger salamander habitat and allows ranchers to continue conducting business in a way that either does not harm or benefits the salamander. Because one of our primary concerns is elimination of Central California tiger salamander habitat, we believe it is appropriate to exempt routine ranching even though it is practiced throughout a large portion of the range of the salamander. As described in Factor C and E below, the Central California tiger salamander is threatened on rangeland by other factors unrelated to habitat loss.
Comment 2: Many commenters including local governments stated that we did not use adequate science in making our decision to propose the Central California tiger salamander as a threatened species. A few commenters stated that the California tiger salamander records from the CNDDB were insufficient because this database lacked observations of the species on private lands.
Our Response: We used the best scientific and commercial information available during the status review process and preparation of the proposed rule to make our listing determination. We used museum records; CNDDB information; GIS coverages documenting the land use changes; unpublished reports by biologists; and peer-reviewed articles from scientific journals in making that determination. Additionally, the proposed rule was peer-reviewed by 11 scientists, researchers, and biologists with amphibian expertise throughout the United States.
Regarding the lack of occurrence data from private lands, the Service is aware that systematic surveys have not been conducted throughout the range of the species. The CNDDB is the clearinghouse for location and status data collected by State and Federal agencies, consultants, scientists, and other knowledgeable biologists on private, State, and Federal lands. We believe that the data in CNDDB, supplemented by information available in other sources and provided by commenters, represents the best available scientific and commercial information on the distribution of the Central California tiger salamander.
Comment 3: Numerous commenters expressed concern that there was not scientific justification for stating that the California tiger salamander can migrate 1 to 2 miles from aquatic breeding habitat into upland habitat.
Our Response: Adult California tiger salamanders have been observed up to 2.1 km (1.3 mi) from breeding ponds (S. Sweet, University of California, Santa Barbara, in litt. 1998), which may be vernal pools, stock ponds, or other seasonal water bodies. During the comment period, the Service received information about a trapping study of California tiger salamanders in West Pittsburg, California, where, during the first three years of the study, 200 to 446 California tiger salamanders were trapped each year 0.8 km to 1.2 km (0.5 to 0.75 miles) away from potential breeding habitat (S. Orloff, in litt. 2003). Additionally, researchers have marked California tiger salamanders in study ponds and have also captured them using pit fall traps in upland migration studies and have determined that the species can migrate up to 670 m (2,200 ft) from breeding ponds to upland habitat (Trenham et al. 2002; Trenham and Shaffer in review).
Comment 4: Numerous commenters stated that the Central California tiger salamander should not be listed as threatened or endangered because the proposed rule does not have population information that would indicate that the species is declining. Commenters also believed that it was inappropriate for the Service to rely on habitat loss for determining the species' decline. One commenter, after conducting a population estimate of the Central California tiger salamander, concluded that there were 840,000 individuals.
Our Response: Based on a review of the scientific and commercial data, the total number of individual California tiger salamanders is not known. The difficulty of estimating the total number of California tiger salamanders has been documented by a number of biologists (Jennings and Hayes 1994; Shaffer et al. 1993). However, estimates have been made for specific locations in Monterey and Alameda counties (Trenham et al. 2000; Kolar in litt. 2003). The fact that this species spends much of its life underground, only a portion of the total number of animals migrate to pools to breed each year, animals do not always breed in their natal pool or pond, and the California tiger salamander's wide distribution make estimating the total number of California tiger salamanders difficult.
To determine the Central California tiger salamander's listing status, we estimated the current distribution and habitat of the species based on known occurrences, and the projected status of the species in the foreseeable future after review of the threats to the DPS from habitat-related and other factors (see Summary of Factors Affecting the Species section below). For habitat-related factors, because of our understanding of the habitat that California tiger salamanders use, and the species' distribution based on known occurrences, we used threats to habitat associated with known occurrences of the Central California tiger salamander as an indication of the status of Central California tiger salamander, in the absence of estimates of the total number of individuals (see Factor A below; Service 2004). The relationship between habitat loss and population decline is further discussed in the Background section above. We also evaluated other threats such as predation from exotic species and the potential threat from disease (see Factor C below), inadequacy of existing regulatory mechanisms (see Factor D below), and hybridization with non-native tiger salamanders (see Factor E below; Service 2004).
The population estimate of 840,000 individuals provided by the commenter is based on an estimate of 1,140 salamanders per pond, which is then extrapolated for the number of breeding sites presented by the commenter. This estimate is largely based on a study conducted by the Loredo and Van Vuren study (1996), which investigated breeding migrations and reproductive traits of California tiger salamanders at a breeding pond in Contra Costa, California. In this study, researchers marked juveniles during three seasons and recaptured mature adults during two of the seasons. The commenter used the mark recapture information presented in the Loredo and Van Vuren study (1996), in addition to survival data for California tiger salamander (Trenham et al. 2000), to conduct the population estimate.
We have determined that the estimate provided by the commenter is speculative and not properly derived because the breeding pond being investigated by Loredo and Van Vuren (1996) may not have been a closed system. At least four other breeding sites were observed in the area (Loredo and Van Vuren 1996). We believe this may have allowed salamanders to migrate into and out of the population being investigated, at unknown rates. Some salamanders also may have lost their marks due to regeneration of clipped toes (Loredo and Van Vuren 1996), and California tiger salamanders that were marked in the first season may not have had an equal opportunity to be recaptured during the following two seasons because salamanders may not mature until four or five years of age (Trenham et al. 2000); thus, individuals would not have migrated to the breeding pond during the study period to allow for possible recapture. We have also concluded that the rangewide estimate for the Central California tiger salamander provided by the commenter is speculative because it extrapolates a population estimate derived from a single site to all sites throughout the range of a species that displays different environmental conditions and population sizes associated with such conditions.
Comment 5: Some commenters stated that the proposed rule did not have information on the range or distribution of the California tiger salamander. Another commenter stated that the current range of the Central California tiger salamander was similar to the species' historic range.
Our Response: We used specific locations of the California tiger salamander identified in the California Department of Fish and Game's CNDDB and additional information provided by outside parties in our analysis of the current distribution of the salamander. Maps illustrating the current known distribution of the animal were available to the public during the comment period upon request from the Sacramento Fish and Wildlife Office. They were also available to the public at six workshops and ten public hearings during the comment period.
We agree that the California tiger salamander still occurs throughout much of its historic range (Trenham et al. 2000), although we estimate approximately 75 percent of the species' historic natural habitat has been lost within this range (Shaffer et al. 1993; see Factor A below). However, we do not believe that the size of the range of the California tiger salamander is the only statistic relevant to an evaluation of listing status. Although the current range of the California tiger salamander approximates its historic range in size, we believe the quality, connectivity, and distribution of the habitat within the range has been substantially altered and degraded.
Comment 6: Several commenters stated that the Service did not conduct population surveys to document in what counties the Central California tiger salamander is located. One commenter stated that the Service did not use best available information on range, abundance, and number of extant populations. Another commenter provided information on additional occurrences of Central California tiger salamander breeding populations and stated that there were more occurrences presently than in the past and that there are 32 percent more occurrences than the Service used in the proposed rule.
Our Response: The Service has determined that the Central California tiger salamander is located within 22 counties, which is based upon CNDDB and other information from biologists, and reports on the species that were available to the Service (see previous response to comment). The CNDDB data base contains information on observations of California tiger salamanders that have been submitted by biologists, researchers, and scientists who have documented the animal's presence at breeding sites and upland habitats. All location information submitted by commenters was used by the Service to make its determination for this final rule. When commenters asserted that additional occurrences exist without providing site-specific information, we attempted to obtain the information independently and/or requested the information from the commenter. If we could not obtain the information or it was not provided to us, we did not evaluate it in our analysis. Therefore, we believe that we used the best available scientific and commercial information in developing this final rule.
Comment 7: One commenter stated that the Central California tiger salamander was not threatened because the species occupies 1.7 million ha (4.1 million ac) of habitat with 737 known breeding populations within its 3.4-million-ha (8.3-million-ac) range.
Our Response: The commenter conducted an independent analysis of the range and habitat of the Central California tiger salamander. Because their methodology differed from ours, their results (i.e., amount of salamander habitat and percentage of habitat likely to be lost) and interpretation also differed substantially from ours. The commenter assumed that all area within a habitat type used by the California tiger salamander was suitable salamander habitat regardless of the location and distribution of suitable aquatic breeding sites within those habitat types (i.e., the sum of grassland, woodland, and other habitat types within the range of the animal). We believe that their approach results in a substantial overestimate of the habitat actually used by extant salamanders.
In contrast, we assessed the amount of salamander habitat based on known salamander location records. These records included all records in the CNDDB, as well as other records provided to us during the comment period. In contrast to the commenters' estimate, we acknowledge that our result is likely to be conservative. Nevertheless, because it is based upon known salamander locations, we believe that our approach yields a more appropriate estimate of the amount of habitat likely to be used by salamanders.
Regarding the 737 California tiger salamander breeding populations presented by the commenter, we used all available information to us for our analysis for this final rule, which represents a total of 711 California tiger salamander records and occurrences. Although the number of breeding populations is important for determining the California tiger salamander's distribution and habitat (as performed in our analysis), the number of breeding sites should not be solely used for assessing the status of the species because the number of breeding sites does not assess the range of the salamander or its distribution relative to historic loss and future threats. Additionally, records within the CNDDB database do not always constitute an observation of a salamander at a breeding site and can be an observation of the species in an upland area.
Details of our approach can be obtained from the Sacramento Fish and Wildlife Office in the document cited here as Service (2004). In addition, the process is described briefly below in the Summary of Factors Affecting the Species section. Based on our analysis, we estimate that there are approximately 378,882 ha (936,204 ac) of Central California tiger salamander habitat, considerably less than the 1,659,214 ha (4.1 million ac) suggested by the commenter.
Some portion of this area will be lost in the future to development (including low- and very-low-density residential) and conversion of rangeland to intensive agriculture. We estimate that 26 percent of the habitat associated with known salamander locations is threatened by conversion, fragmentation, and degradation from urbanization and low- and very-low-density residential development in the future. This estimated loss of habitat does not include the continued loss of habitat that has occurred as a result of conversion of habitat to intensive agriculture. In addition, California tiger salamanders are at risk from hybridization with non-native tiger salamanders, predation and other factors discussed in the Summary of Factors below.
The primary threats include habitat destruction, degradation, and fragmentation due to urban development, and conversion to intensive agriculture. Other threats include hybridization with non-native salamanders and predation.
Comment 8: Many commenters stated that the Central California tiger salamander did not require listing under the Act because it was already protected by existing regulatory mechanisms. Examples of current regulations cited include the application of the Porter-Cologne Water Quality Control Act, California Environmental Quality Act (CEQA) by CDFG, Clean Water Act, and species listed under the Endangered Species Act, such as vernal pools species, vernal pool critical habitat, California red-legged frog, and the San Joaquin kit fox. One commenter stated that habitat conservation plans provide protection for the California tiger salamander. Many commenters, including local governments in Merced County, stated that the Central California tiger salamander was presently protected in Merced County by a 20,000-acre conservation easement program that acts as an existing regulatory mechanism. A few other commenters indicated that Merced County had existing regulatory mechanisms sufficient to protect the Central California tiger salamander through the Clean Water Act as well as to protect its habitat on waterfowl easements and on the San Luis National Wildlife Refuge. Commenters also mentioned existing protections that occur from local land use laws such as county plans and local ordinances. A few commenters also stated that the Williamson Act provides regulatory protection to the Central California tiger salamander.
Our Response: Existing regulatory mechanisms may afford some regulatory protection to the Central California tiger salamander. However, the protection afforded by these regulations does not sufficiently protect the species to such an extent that listing is not warranted (see Factor D). In addition, the species is threatened by hybridization with non-native tiger salamander, predation, and other threats (see Factors C, D, and E below), that existing regulatory mechanisms do not alleviate. Regarding protected areas in Merced County, San Luis National Wildlife Refuge and other areas, we incorporated these areas into our analysis for estimating the amount of protected Central California tiger salamander habitat (see Factor A). While many of these areas may be protected from habitat destruction, California tiger salamanders on some of these otherwise protected lands are still threatened by hybridization, predation, and other non-habitat based threats (Factors C, D, and E).
Comment 9: Several commenters stated that there are no diseases adversely affecting the Central California tiger salamander and that the discussion on disease as a threat in the proposed rule was speculative. Several commenters stated that the Service was on record that disease did not pose a threat to the California tiger salamander.
Our Response: As stated in the proposed rule, the Service acknowledges that relatively little is known about the diseases of wild amphibians in general (Alford and Richards 1999) and California tiger salamander in particular (see Factor C below). Pathogen outbreaks have not been documented in the Central California tiger salamander, and while two of the peer reviewers expressed concerns that disease could pose a future threat to the California tiger salamander, we currently do not have specific information to consider it a threat.
Comment 10: A few commenters expressed concern about the estimate of 4,451,549 ha (11.1 million ac) of habitat available for the Central California tiger salamander referenced in the proposed rule. These commenters stated that this estimate of potential habitat did not coincide with our estimates of habitat estimated for the four populations that are part of the Central California tiger salamander in the proposed rule. One commenter stated that the Service estimated the amount of habitat for the Central California tiger salamander without correlating potential habitat with distributional data for the species. One commenter stated that the Service did not ground truth California tiger salamander records that were determined to be extirpated as part of the proposed rule's GIS analysis (Service 2003).
Our Response: The 4,451,549 ha (11.1 million ac) referred to in the proposed rule was a typographical error; the correct estimate was 445,155 ha (1.1 million ac), which represents the sum of polygons representing presumed extant records surrounded by an area 2.4 km (1.5 mi) wide to represent additional habitat that could be associated with Central California tiger salamander observations. Records were determined to be extant as recorded by the individual that made the observation, and refined through additional GIS analysis by the Service of records of California tiger salamander observation sites likely destroyed by existing urbanization and intensive agriculture, or where the California tiger salamander is threatened by hybridization with non-native tiger salamanders. Within the 445,155 ha (1.1 million ac), we estimated that there was approximately 283,280 ha (700,000 ac) of Central California tiger salamander habitat.
Our estimate of distribution of existing Central California tiger salamander habitat was based upon the evaluation of California tiger salamander records and observations, together with other information on current land uses and habitat types associated with those locations. Using commenter's suggestions on our methodology and other new information received, we conducted a new analysis for this final rule. Our analysis methodology is described in greater detail below in the Summary of Factors.
With respect to ground-truthing CNDDB records, the commenter is correct. While we visited as many sites as time allowed, our resources limited us to visiting only a fraction of the sites. Additional information from an increased number of site visits would have been useful, but in its absence, we have made this determination based on the best information available to us.
Comment 11: Several commenters expressed concern that the proposed rule made contradictory statements regarding agricultural crops as habitat for the Central California tiger salamander while also discussing agriculture as a threat to the species. Another commenter stated that agriculture is not a threat because the total quantity of agricultural lands in the state is declining with the increasing human population.
Our Response: While intensive agriculture is partially responsible for removal of historic California tiger salamander habitat, we recognize the contribution that some agricultural practices like rangeland ranching make to California tiger salamander survival. Accordingly, we are promulgating a rule to allow ordinary and usual ranching practices to be exempt from the Act.
Comment 12: Another commenter stated that development was not a threat to the Central California tiger salamander based on an analysis of impacts on Central California tiger salamander potential habitat projected by general plans. The commenter's independent analysis showed that 75 records and 127,192 ha (314,297 ac) of suitable habitat fall within areas designated by general plans for urban development. By this analysis, 88 percent of the localities (567 records) and approximately 92 percent of the suitable habitat (1,537,808 ha (3,800,000 ac)) are not threatened by development. Additionally, the commenter's analysis included review of open space designations and other forms of conservation. This review identified 96 records (15 percent) and 233,103 ha (576,008 ac) of habitat (14 percent) as protected from development. This commenter identified 25 sites that met the requirements of California tiger salamander preserves (Shaffer et al. 1993).
Our Response: We discussed above (see Response to Comment 6) a fundamental difference between our analysis and the commenter's analysis. We believe that the commenter's methodology resulted in a substantial overestimate of the amount of California tiger salamander habitat. Their subsequent estimates, such as the amount and percentage of habitat falling within general plan areas or within protected areas, rely on their estimation of salamander habitat. Because we believe the underlying habitat estimate to be inappropriate, we believe the subsequent estimates are questionable as well.
Despite the difference between the commenter's estimate of salamander habitat and our estimate of habitat, these analyses are similar in that both utilized general plans and planned development for estimating habitat loss. Our analysis also included habitat loss, fragmentation, and degradation as a result of low-density and very-low-density development, and we considered habitat conversion to intensive agriculture to also be a threat. The commenter did not use or consider these factors in their analysis (see Factor A below). Regarding the commenter's estimate of protected habitat, their percentage estimate (14 percent) is slightly less than ours (20 percent), despite that fact that we used different information to determine protected habitats.
Our analysis indicated that approximately 28,526 ha (70,489 ac, or 8 percent) of Central California tiger salamander habitat is threatened by development identified in general plans or by other planned development (Factor A). Our 8 percent estimate of Central California tiger salamander habitat threatened by development identified in general plans or by other planned development is similar to the commenter's estimate. Additionally, we determined 24,240 ha (59,897 ac, or 6 percent) of Central California tiger salamander habitat is threatened by low-density housing and 45,880 ha (113,371 ac, 12 percent) by very-low-density housing (Factor A). The general plans that we used for this analysis represent the planning area for local governments. Planning for many areas does not extend beyond 2020, while California's growth rates are projected to continue to grow for at least the next 40 years (see Factor A below). Therefore, our estimate of habitat likely to be converted to land uses incompatible with Central California tiger salamander persistence is likely to be conservative. Our estimate is also conservative because it does not consider the loss of habitat due to conversion to intensive agriculture. Projecting the future loss of Central California tiger salamander habitat from conversion of rangeland to intensive agriculture is difficult because conversion to this land use is largely unregulated by cities and counties and is dependent upon the individual landowner and numerous factors that are difficult to predict, such as economic considerations, markets, and water availability.
We also determined that 76,501 ha (189,032 ac, or 20 percent) are afforded some protection (see Factor A below). The percentage of habitat within protected areas varies across the Central California tiger salamander range from 2 to 27 percent (see Factor A below).
We also evaluated the additional information received after the closing of the comment period regarding the issue of agricultural land conversion back from intensive use to areas no longer in production and determined that our analysis of existing California tiger salamander habitat was correct and that these land conversions are not resulting in an increase in habitat available to the California tiger salamander.
Comment 13: We received information from several commenters on specific projects and their impacts to California tiger salamander.
Our Response: These comments were not accompanied by information we could use to substantiate the status of each project (e.g., photographs, environmental documents). To the extent that we could independently verify the information submitted, we included it in our analysis.
Comment 14: Another commenter stated that planned development areas should not be considered areas of potential impact due to avoidance, minimization, and mitigation. Additionally, this commenter stated that development will not go beyond general plans.
Our Response: Planned development may often provide avoidance, minimization, and mitigation measures which are specifically for, or which may incidentally benefit, California tiger salamander. These measures result from conformance with local land use plans for providing open space, through working with the California Department of Fish and Game under the authority CEQA, or through working with the Service when other federally listed species are present. The avoidance, minimization, and mitigation measures of individual projects, nevertheless, tend to result in fragmented landscapes and a trend of cumulative regional habitat loss and fragmentation. Mitigation does not create new land, it simply balances land converted with land protected for natural values, so even with mitigation, a net loss of habitat results. We tried to reflect the overall effect of this balancing in our Factor A analysis when we looked at the amount of protected lands and lands being converted to urban uses. We did not project development beyond general plans except where we had specific information that indicated otherwise (see Factor A).
Comment 15: A number of commenters stated that the Service should provide a map to landowners, counties, and other local governments with records of California tiger salamanders and their habitat. A few commenters stated that the Service should provide a map with records of California tiger salamanders and their habitat together with designated critical habitat for listed vernal pool species. A few commenters stated that the proposed rule did not present maps with the historic habitat for the Central California tiger salamander.
Our Response: At each of our public workshops and hearings, we provided maps that identified California tiger salamander locations that were available for the public. We also brought larger maps that explained much of our five-factor analysis with respect to the Central California tiger salamander. At each of these hearings and workshops, biologists were available to discuss the species with interested persons. These maps were also available from the SFWO upon request. Regarding the request for maps to provide the location of historic habitat for the Central California tiger salamander, we provided information on the species' historic range in the proposed rule and in this final rule.
Comment 16: A few commenters stated that the Service was assuming that all vernal pools represented aquatic breeding habitat for the species.
Our Response: The Service is not assuming that all vernal pools represent breeding habitat for the California tiger salamander. We consider vernal pools within the vicinity of known California tiger salamander records likely breeding habitat if they pond for a sufficient amount of time for larvae to metamorphose in some years. A given vernal pool may not hold water for a sufficient amount of time every year due to variability in the duration of pool inundation from one year to another.
Comment 17: One commenter stated that there was no evidence that non-native fish and crayfish or wild pigs pose any threat to the Central California tiger salamander. This commenter also stated that bullfrogs are being eliminated by the control programs that are outlined in the California red-legged frog recovery plan, and, consequently, bullfrog populations will decrease in the future. Another commenter stated that the proposed rule did not quantify the threat of exotic species on the Central California tiger salamander.
Our Response: While predation in and of itself may not threaten California tiger salamander, studies indicate, although not quantitatively, a strong negative correlation between the presence of the California tiger salamander and the presence of various species, including the bullfrog (Shaffer et al. 1993; Seymore and Westphal 1994; Laabs et al. 2001); mosquitofish (Loredo-Prendeville et al. 1994; Leyse and Lawler 2000; Leyse in litt. 2003); non-native fish species (Fisher and Shaffer 1996; Laabs et al. 2001); crayfish (Jennings and Hayes 1994); and wild pigs (Waithman et al. 1999). These studies suggest that predation can negatively affect the persistence of California tiger salamander populations.
The California tiger salamander may incidentally benefit in some ways from the Act's regulatory protection of the California red-legged frog. However, we believe that these protections will only partially protect the California tiger salamander because the two species only co-occur in certain areas and have differing habitat requirements in some phases of their life cycles.
Comment 18: Several commenters stated that the Service was on record stating that pesticides were not a threat to the California tiger salamander (Service citing Davidson et al. 2002). Other commenters stated that pesticides are not a threat and their use in California is declining.
Our Response: We acknowledge that most toxicological studies to date have not been conducted on California tiger salamander, but rather on other amphibian species, in particular Anuran species (frogs and toads). California tiger salamanders may be sensitive to pesticides and other chemicals, which may be found in both the aquatic and terrestrial habitats they use in different stages of their life cycle (Blaustein and Wake 1990) (see factor C below).
We agree information indicates that pesticide use (measured by pounds of active ingredient) in California has declined between 1992 and 2002 (California Department of Pesticide Regulation website). However, in 2002 eight of the top ten pesticide-using counties were in the range of the Central California tiger salamander. We believe that California tiger salamanders may be at risk from the use of pesticides because salamanders occur in the vicinity of agricultural lands where pesticides are often used (e.g., along the east side of the San Joaquin Valley). See also Factor E below.
Comment 19: A few commenters stated that ground squirrel control was not a threat to the California tiger salamander because the control of ground squirrels in the state is declining. Another commenter stated that rodenticides do not pose a threat to the California tiger salamander any more than they do to burrowing owls.
Our Response: California ground squirrel control may be done by trapping, shooting, fumigation of burrows, use of toxic (including anticoagulant) baits, and habitat modification, including deep-ripping of burrow areas (UC IPM internet website 2004). These control programs are still widely conducted by numerous local and state agencies. We received no data to suggest that active rodent control is declining. Two of the most commonly used rodenticides, chlorophacinone and diphacinone, are anticoagulants that cause animals to bleed to death (see Factor E below). These chemicals can be absorbed through the skin and are considered toxic to fish and wildlife (EPA 1985; EXOTONET 1996). These two chemicals, along with strychnine, are used to control rodents (R. Thompson, in litt. 1998). There are no specific studies to determine the direct effects of these poisons on California tiger salamander. However, based on studies of similar amphibian species, any uses in close proximity to occupied Central California tiger salamander habitat could have various direct and indirect toxic effects. Gases, including aluminum phosphide, carbon monoxide, and methyl bromide, are used in rodent fumigation operations and are introduced into burrows by either using cartridges or by pumping. When such fumigants are used, animals inhabiting the fumigated burrow are killed (Salmon and Schmidt 1984).
Comment 20: A few commenters stated that mosquito control did not represent a significant threat to the Central California tiger salamander because other forms of control were being utilized to reduce the use of this fish as a control strategy.
Our Response: We believe that mosquito control activities can be readily adapted to prevent or minimize potential threats to salamanders by appropriate water level management of stock ponds or proper application of bacterial larvicides. As a result, we have exempted some forms of mosquito control undertaken as routine ranching activities from the take prohibitions of the Act (see Special Rule below).
Comment 21: One commenter stated that there is not evidence that roads place California tiger salamander populations at risk, and that minimization measures, such as culverts, are established for safe passage.
Our Response: Significant numbers of various species are killed by vehicular traffic while crossing roads (Hansen and Tremper 1993; S. Sweet in litt. 1993; Joe Medeiros, Sierra College, pers. comm. 1993), including California tiger salamanders (D. Cook, pers. comm. 2002; see Factor E below). Loss of California tiger salamanders to vehicular-caused mortality in the vicinity of breeding sites can range from 25 to 72 percent of the observed salamanders crossing roads (Twitty 1941; S. Sweet, in litt. 1993; Launer and Fee 1996). As vehicular usage on California roads and road density continue to increase with increases in human population and associated urban expansion (California Department of Transportation internet website 2003), the threat to California tiger salamanders from road-kill mortality will increase. Unless there is a means of directing the species to a culvert, we have no data suggesting that a salamander would seek or use a culvert in preference to just crossing a road at the place they encountered one, or that the presence of culverts reduces crossing risk to salamanders.
Comment 22: Some commenters stated that we did not discuss the usefulness of stock ponds for the species.
Our Response: Stock ponds can be useful aquatic habitats for breeding of the Central California tiger salamander. However, stock ponds require management to ensure their long-term habitat suitability for the species (Shaffer in litt. 2003; see 4(d) rule below). We recognize the usefulness of stock ponds as potential breeding habitat for the California tiger salamander and encourage their continued use through the 4(d) rule that exempts routine ranching activities.
Issue 2. Listing Process
Comment 23: Many commenters stated that the California Fish and Game Commission had reviewed a petition to list the California tiger salamander under the California Endangered Species Act and had determined that the listing was not warranted. Many of these commenters stated that since California Fish and Game Commission made this determination there has been no new scientific information to indicate that the species warrants protection under the Act.
Our Response: California Fish and Game Commission determined that the listing of the California tiger salamander was not warranted under the California Endangered Species Act. The Service has proposed listing the Central California tiger salamander as a threatened species based on our evaluation of the status of the species and five factor analysis, and the best available commercial and scientific information as required by the Federal Endangered Species Act.
Comment 24: A few commenters stated that the information used in the original petition (Shaffer et al. 1993) was for the purpose of conducting genetic analysis of the species or that the petition did not provide an adequate argument for the species to be listed.
Our Response: In our evaluation of a listing petition and subsequent status survey and eventual listing determination, we are required to evaluate all information available regarding the status of a species when making a listing determination. Our positive findings for the 90-day, 12-month, proposed listing rule, and this final listing rule use the best scientific and commercial data available, as we are required to use in reaching our conclusions.
Comment 25: Many commenters stated that the information used by the Service in the proposed rule was not shared or available to the public.
Our Response: As stated in the proposed rule, the complete file for the rule is available for inspection, by appointment, during normal business hours at the Sacramento Fish and Wildlife Office. In addition, the proposed rule stated that all comments received during the comment period were available for public review. The complete file for this rule is available for inspection, by appointment, during normal business hours at the Sacramento Fish and Wildlife Office.
Comment 26: Many commenters stated that the proposed listing was a “rushed process” and these commenters requested further review and scientific analysis before the Service makes a final determination.
Our Response: The purpose of publishing a proposed rule and soliciting public input during the comment period is to fully involve the public in the listing process. We held six workshops and 10 public hearings in California to encourage agency and public input into the review of the proposed rule. We solicited 28 recognized experts and specialists to review the proposed rule and received responses from 11 of these experts. We utilized this information in making the final determination. In order to receive adequate information from the public, we extended the public comment period twice. In total, the comment period was open for 150 days.
Comment 27: Several commenters stated that the proposed listing should undergo a scientific peer review before the Service makes a final determination. Another commenter stated that the Service did not conduct a meaningful peer review because the Service requested the same information from peer reviewers as it did from the general public.
Our Response: In accordance with our July 1, 1994, Interagency Cooperative Policy for Peer Review in Endangered Species Act Activities (59 FR 34270), we solicited review from 28 experts in the fields of ecology, conservation, genetics, taxonomy and management. The purpose of such a review is to ensure that listing decisions are based on scientifically sound data, assumptions, and analyses, including input from appropriate experts. The 11 peer reviewers who provided comments on the proposed listing supported the listing of the Central California tiger salamander as threatened. Peer reviewers provided additional documentation of threats to the species and potential conservation measures. That information has been incorporated into this final rule. We also requested peer review from nine university scientists on the mitochondrial DNA (mtDNA) study of the California tiger salamander conducted by Dr. H.B. Shaffer and Dr. P.C. Trenham of the University California at Davis (Shaffer and Trenham 2003). Three researchers reviewed the report. Their comments are summarized above in the Peer Review section.
Issue 3. Cost and Regulatory Burden
Comment 28: Many commenters, including local governments, stated that the listing of the Central California tiger salamander would increase regulatory burdens and costs of completing projects and would have a negative impact on the local economy. Several commenters stated that the Service needs to address the economic impact in the proposed listing of the Central California tiger salamander. Several commenters stated that the listing would reduce local government's authority over land use decisions. Commenters also stated that the listing would have a negative impact on the California and national economies. Several commenters stated that if the Central California tiger salamander were listed, it would be expensive to hire consulting biologists and provide mitigation. One commenter requested that if the Central California tiger salamander were listed, then mitigation ratios for projects impacting California tiger salamanders and survey protocols be published simultaneously with the final rule. A few commenters expressed concern about the regulatory burden the proposed Central California tiger salamander listing would place on pesticide application, mosquito control, rodent control, and the relation of these regulated activities to human health. One commenter expressed concern about whether existing agricultural practices would constitute a section 9 violation if the Central California tiger salamander were listed. One commenter requested that all activities that do not constitute a section 9 violation be listed in the final rule.
Our Response: Under section 4(b)(1)(A) of the Endangered Species Act of 1973, as amended (Act) (16 U.S.C. 1531 et seq.), we must base a listing decision solely on the best scientific and commercial data available. The legislative history of this provision clearly states the intent of Congress to ensure that listing decisions are “ * * * based solely on biological criteria and to prevent non-biological criteria from affecting such decisions * * * ” (House of Representatives Report Number 97-835, 97th Congress, Second Session 19 (1982)). As further stated in the legislative history, “ * * * economic considerations have no relevance to determinations regarding the status of species * * * ” (Id. at 20). Therefore, we did not consider the economic impacts of listing the Central California tiger salamander.
In our Notice of Interagency Cooperative Policy of Endangered Species Act Section 9 Prohibitions (59 FR 34272, July 1, 1994), we stated our policy to identify, to the extent known at the time a species is listed, specific activities that will not be considered likely to result in violation of Section 9. In accordance with that policy, we have published in this final rule a list of activities we believe will not result in violation of Section 9 of the Act (see Available Conservation Measures below).
Comment 29: One commenter stated that California tiger salamanders that hybridized with non-native tiger salamanders should not be afforded regulatory protections under the Act if the Central California tiger salamander were listed and that we were inconsistent with the recent westslope cutthroat trout determination (68 FR 46989).
Our Response: We do not believe our determination here is inconsistent with the 12-month finding for the listing of the westslope cutthroat trout (Oncorhynchus clarki lewisi) (68 FR 46989). We noted in that finding that “our increasing understanding of the wide range of possible outcomes resulting from exchanges of genetic material between taxonomically distinct species, and between entities within taxonomic species that also can be listed under the Act (i.e., subspecies, DPSs), requires the Service to address these situations on a case-by-case basis” (68 FR 46992). We also stated our intention to evaluate long-term conservation implications for each taxon separately on a case-by-case basis where introgressive hybridization may have occurred.
Distinguishing between native California tiger salamanders and hybrid animals appears to require some scientific and technical expertise. We understand that it is difficult for non-experts to make the distinction based on morphology alone and that a number of misidentifications have been made as a result (Shaffer and Trenham 2002). The best way to identify hybrid or introgressed individuals at this point appears to be using sophisticated molecular genetic techniques. Because of the difficulty distinguishing hybrid and introgressed individuals from native California tiger salamanders, we believe it is both inappropriate and impractical to distinguish between them under the Act.
Comment 30: A few commenters expressed concern about the potential regulatory protection to ground squirrels that would result from listing the Central California tiger salamander and the ground squirrel's relation to incidences of the plague. Several other commenters also stated that the potential regulatory protection to ground squirrels would result in their inability to conduct rodent control in the interest of public health.
Our Response: In situations where human health and safety are at risk, human health and safety concerns would be a priority in making decisions about appropriate rodent control. We believe that ground squirrel control can occur in a manner that minimally affects California tiger salamander.
Issue 4. Notification and Public Comment
Comment 31: A number of commenters stated that landowners were either not notified, or not notified in a timely manner, and not given an adequate opportunity to comment on the proposed rule. The commenters also stated that the number of public hearings was inadequate to obtain full public input on the proposal and that additional public hearings should be held. A number of commenters also stated that the comment period on the proposed rule should be extended from September 22, 2003, to allow for additional outreach to interested parties as well as to hold more public hearings.
Our Response: We are obligated to hold at least one public hearing on a listing proposal, if requested to do so prior to 15 days before the end of a comment period (16 U.S.C. 1533(b)(5)(E)). We held a total of 10 public hearings on our proposal to list the Central California tiger salamander as a threatened species, the proposed reclassification of the Santa Barbara and Sonoma DPSs from endangered to threatened, and the proposed exemption for routine ranching activities. We also held six public workshops to notify the public of the proposed rule and to answer questions regarding the California tiger salamander and the proposed rule. In addition to the public hearings and public workshops, we attended a public meeting organized by Congressmen Dennis Cardoza and George Radanovich in Merced, California, on June 12, 2003, and in Modesto, California, on October 24, 2003, to discuss the proposed rule and answer questions regarding the California tiger salamander and the proposed rule.
Written public comments were accepted at all the public hearings, workshops, and the Merced and Modesto meetings, and entered into the supporting record for the rulemaking. Oral comments given at the public hearings were also accepted into the supporting record. In making our decision on the proposed rules, written comments were given the same weight as oral comments presented at hearings. We conducted much of our outreach about the proposed listing of the Central California tiger salamander through legal notices in numerous regional newspapers, telephone calls, letters, and news releases faxed and/or mailed to appropriate elected officials, local jurisdictions, and interest groups. We also posted the proposed rule, schedule of workshops and hearings, and other associated material on our Sacramento and Ventura Fish and Wildlife Office internet sites. We believe that our notification and outreach process was sufficient to make the public aware of this proposal. Further, our efforts in this process satisfied the requirements of the Act and the Administrative Procedure Act (5 U.S.C. 551 et seq.) (APA) for promulgating Federal regulations regarding listing actions.
The comment period for the proposed rule was initially open for 60 days, closing on July 22, 2003. On July 3, 2003, we extended the comment period until September 22, 2003. The comment period was re-opened on September 30, 2003, for an additional 30 days and closed on October 31, 2003. In total, the comment period was open for 150 days.
Comment 32: A few commenters stated that the Service should provide more information regarding the proposed rule on our website.
Our Response: Information on the California tiger salamander was available on our website (http://sacramento.fws.gov) related to the proposed rule, workshops, hearings, the status of the comment period, biological information, and contacts to gather additional information on the species. An e-mail address posted on our website offers the public the opportunity to offer suggestions or request the webmaster to include additional information.
Comment 33: One commenter stated that minority and disadvantaged people were not given the opportunity to comment on the proposed rule.
Our Response: We conducted extensive public outreach (see also comments 26 and 31 above) on the proposed rule to inform all affected stakeholder groups and populations, with the reasonable expectation that the information would reach minority and disadvantaged populations. For instance, we scheduled 10 workshops and public hearings throughout California and released information to the news media in communities with substantial minority and disadvantaged populations. We also produced news releases that were widely distributed to newspapers and radio and television stations throughout the state; posted information on Fish and Wildlife Service internet sites, and placed notices in newspapers in communities with a large percentage of minority residents. In addition, as stated in the Federal Register notice, persons needing reasonable accommodations in order to attend and participate in the public hearings could contact the Sacramento Fish and Wildlife Service Office at least one week prior to the hearing.
Issue 5. Property Rights
Comment 34: Several commenters stated that the listing would result in the loss of property rights and decreased land values.
Our Response: The listing of a species and the functioning of the Act does result in the imposition of land use constraints. However, we have attempted to address only those activities that threaten the continual existence of the California tiger salamander. We have exempted many routine ranching activities from the take prohibitions of Section 9 of the Act through the special rule. We will assist landowners in the identification of proposed activities that could result in take (harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in any such conduct), develop measures to minimize the potential for take, and work with them to obtain authorizations for incidental take through sections 7 and 10 of the Act. Recovery planning for this species may include recommendations for land acquisition or easements involving private landowners. Any such efforts will be undertaken with the full cooperation of the landowners.
Issue 6. Critical Habitat and Recovery Planning
Comment 35: Several commenters expressed concern that the proposed rule included or was a designation of critical habitat for the Central California tiger salamander. Several of these commenters stated that their property did not have the species or its habitat present on their property and that they requested that their property be exempted from the proposed critical habitat designation. A few commenters stated that the Service should designate critical habitat for the California tiger salamander. A few commenters stated that the discussion on critical habitat designation in the proposed rule was inappropriate.
Our Response: We are proposing critical habitat for the Central California tiger salamander population in an upcoming rule. In addition we will finalize critical habitat for the Santa Barbara California tiger salamander population by the court-ordered deadline of November 15, 2004. We intend to publish a proposed rule to designate critical habitat for the Sonoma geographic area in the future. When that rule is finalized, the critical habitat designation for the rangewide California tiger salamander will be complete.
Comment 36: Several commenters stated that the Service should also complete a recovery plan for the species. Several commenters, including local governments, requested that, if the species were listed, then they should be able to review a draft version of the recovery plan.
Our Response: A recovery plan will be developed, in coordination with stakeholders. This plan will identify recovery objectives and describe specific management actions necessary to achieve the conservation and long-term survival of the species. We anticipate that these management actions will include habitat protection and restoration, and efforts to conduct further surveys and research on this species. The draft recovery plan will be made available for public review and comment once it has been prepared.
Issue 7. Designation and Listing Status of the Central California Tiger Salamander
Comment 37: Numerous commenters stated that the Central California tiger salamander should be listed as an endangered species rather than threatened.
Our Response: As discussed in this final rule, we have concluded that the appropriate listing status is threatened. While there are a number of factors that put the population at risk, they are not so imminent that we believe the population is in danger of extinction at this time (i.e., it does not meet the definition of endangered). Rather, we believe the Central California tiger salamander is likely to become endangered throughout all or a significant portion of its range in the foreseeable future (i.e., it meets the definition of threatened).
Comment 38: A few commenters stated that the Central California tiger salamander does not qualify as a Distinct Population Segment or that it is inappropriate to consider it a DPS given the listing of Santa Barbara and Sonoma counties as DPSs (i.e., we should have considered the species range wide instead of piece by piece). Another commenter stated the Central California tiger salamander DPS should be designated as four DPSs corresponding to the four sub-populations of the Central California tiger salamander. In contrast, a different commenter stated that there was no basis to subdivide the Central California tiger salamander into four DPSs.
In addition to these general comments about the appropriateness of considering Central California tiger salamander a DPS, we received several comments about whether the DPS meets the significance criterion of our DPS policy. In part these comments focused on our recent 12-month finding on western gray squirrel and on National Ass'n of Homebuilders, et al. v. Norton, et al., No. 00-0903-PHX-SRB (D.Az.), recent litigation about our DPS determination for the cactus ferruginous pygmy owl.
Our Response: We have determined that listing the California tiger salamander rangewide is appropriate in light of the fact that all three populations share the same threatened status and the Congressional direction to use the DPS provision sparingly.
Issue 8. Proposed 4(d) Rule To Exempt Existing Routine Ranching Activities
Comment 39: Several commenters indicated that the proposed 4(d) rule to exempt existing routine ranching activities did not adequately define the activities proposed from exemption in the proposed rule. Many commenters made specific recommendations for additional activities they thought should be exempted in the special rule. Additional activities suggested for exemption included activities such as dairy operations, irrigated agriculture, and ground squirrel control, projects that have received approval from Federal, State, and local governments, and livestock grazing in vernal pools. One commenter stated that the Service should exempt take through conservation plans.
Our Response: The final version of the special rule includes an expanded definition of routine ranching practices and incorporates additional activities we believe are consistent with conservation of the California tiger salamander, which may provide conservation benefits to the California tiger salamander through private landowner partnerships, and which are associated with largely natural rangeland environments with low, infrequent levels of human activity, in which California tiger salamander persist.