Ambystoma californiense - Gray, 1853
California Tiger Salamander
Other English Common Names: California tiger salamander
Taxonomic Status: Accepted
Related ITIS Name(s): Ambystoma californiense Gray, 1853 (TSN 173595)
Unique Identifier: ELEMENT_GLOBAL.2.104488
Element Code: AAAAA01180
Informal Taxonomy: Animals, Vertebrates - Amphibians - Salamanders
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Amphibia Caudata Ambystomatidae Ambystoma
Genus Size: D - Medium to large genus (21+ species)
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Concept Reference
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Concept Reference: Collins, J. T. 1990. Standard common and current scientific names for North American amphibians and reptiles. 3rd ed. Society for the Study of Amphibians and Reptiles. Herpetological Circular No. 19. 41 pp.
Concept Reference Code: B90COL01NAUS
Name Used in Concept Reference: Ambystoma californiense
Taxonomic Comments: Formerly regarded as a subspecies of Ambystoma tigrinum. See Kraus (1988), Shaffer et al. (1991), and Jones et al. (1993) for phylogenetic analyses of North American Ambystoma; these analyses treated californiense as a distinct species.

Based on genetic analysis, there are six populations of California tiger salamanders, distributed as follows: (1) Santa Rosa area of Sonoma County; (2) Bay Area (central and southern Alameda, Santa Clara, western Stanislaus, western Merced, and the majority of San Benito counties); (3) Central Valley (Yolo, Sacramento, Solano, eastern Contra Costa, northeast Alameda, San Joaquin, Stanislaus, Merced, and northwestern Madera counties); (4) southern San Joaquin Valley (portions of Madera, central Fresno, and northern Tulare and Kings counties); (5) Central Coast Range (southern Santa Cruz, Monterey, northern San Luis Obispo, and portions of western San Benito, Fresno, and Kern counties); and (6) Santa Barbara County (Shaffer and Trenham 2002).

USFWS (2000, 2002) reviewed the biogeographical and genetic information supporting the recognition of the Santa Barbara County population and Sonoma County population as distinct population segments under the U.S. Endangered Species Act.
Conservation Status
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NatureServe Status

Global Status: G2G3
Global Status Last Reviewed: 06May2014
Global Status Last Changed: 06May2014
Rounded Global Status: G2 - Imperiled
Reasons: Restricted to the central portion of California, where range and abundance have declined substantially as a result of habitat loss and degradation and other factors related primarily to human population growth and agricultural expansion. These factors, as well as hybridization with non-native tiger salamanders, effects of non-native species, and habitat fragmentation continue to threaten many populations. Although the species still occurs throughout most of the historical range and remains locally common in some areas, the recent and projected future rate of decline remains high. Consequently, the species was federally listed as Threatened rangewide in 2004.
Nation: United States
National Status: N2N3 (21May2001)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States California (S2S3)

Other Statuses

U.S. Endangered Species Act (USESA): LE, LT: Listed endangered, listed threatened (04Aug2004)
Comments on USESA: The California tiger salamander is listed threatened throughout its range, except for the Sonoma County and Santa Barbara County Distinct Population Segments, where it is listed endangered.

On 8/4/04, USFWS listed the CA tiger salamander as threatened throughout its range. In doing so, the status of the Santa Barbara and Sonoma county populations were changed from endangered to threatened. Federal Register 69:47212, August 4, 2004.

On 8/19/05 U.S. District Judge William Alsup vacated the Service's downlisting of the Sonoma and Santa Barbara populations from endangered to threatened. The Sonoma and Santa Barbara populations are once again listed as endangered.

The remainder of the range (called the Central CA DPS) is listed threatened.

U.S. Fish & Wildlife Service Lead Region: R8 - California-Nevada
IUCN Red List Category: VU - Vulnerable

NatureServe Global Conservation Status Factors

Range Extent: 20,000-200,000 square km (about 8000-80,000 square miles)
Range Extent Comments: Discontinuous distribution in west-central California: coast ranges between Sonoma and Santa Barbara counties, Central Valley and surrounding foothills from southern Colusa County to northwestern Kern County on the west side of the valley and southern Butte County to northern Tulare County on the east side.

This species has been eliminated from much of the historical range in the Central Valley as a result of agricultural and urban development (Stebbins 1985), but it still occurs throughout most of overall historical range and can be locally common (Trenham et al. 2000). About 80% of all extant occurrences are in Alameda, Contra Costa, Madera, Merced, Monterey, San Benito, ad Santa Clara counties, with 30% of all occurrences in Alameda County. Recently rediscovered on the San Francisco Peninsula (Lagunita Lake, Stanford University) (Barry and Shaffer 1994). See Jennings (1996, Herpetological Review 27:147) for an old record from San Mateo County. Elevational range from near sea level to 1054 m.

The Sonoma County population is geographically separated from the closest populations (in Contra Costa, Yolo, and Solano counties) by the Coast Range, Napa River, and the Carquinez Straits, a distance of about 72 km. This population occurs on the Santa Rosa Plain, an area of about 6.8 x 4.4 km (USFWS 2002). The historical range may have included the Petaluma River watershed, as there is one record of a specimen from the vicinity of Petaluma from the mid-1900s (Borland 1856, cited by Storer 1925).

Area of Occupancy: 501 to >12,500 4-km2 grid cells
Area of Occupancy Comments: USFWS (2004) estimated that there are 3,788 sq km of habitat associated with known records. This estimate excludes unsuitable habitat (urbanized areas, areas of intensive agriculture) and assumes that salamanders occupy an area extending approximately 2 km (2,092 m) around each known occupied location. Use of the latter assumption, based on the maximum known distance a salamander may migrate from a breeding site, likely leads to an overestimate of the extent of occupied area for known populations, but USFWS (2004) concluded the overestimate is not a significant error "because additional California tiger salamander breeding locations that have not been surveyed are likely to exist within the 2,092-m (1.3-mi) boundary." While this may be true, the area of known occupied habitat is probably considerably less than 3,788 sq km and easily could be closer to half that amount (probably most individuals move less than 1 km from the breeding site) (see USFWS 2004:47216).

Number of Occurrences: > 300
Number of Occurrences Comments: Presumed extant in several hundred sites (USFWS 2004); likely there are a smaller number of distinct occurrences (discrete populations). In the Los Vaqueros watershed, Contra Costa County, Alvarez (2004) found this species in 66 of 90 stock ponds.

The Santa Barbara County distinct population segment occupies six habitat complexes with 27 documented breeding sites; these represent six metapopulations (USFWS 2000).

Sonoma County distinct population segment: currently there are 8 known breeding sites (USFWS 2003).

Population Size: 10,000 - 100,000 individuals
Population Size Comments: Total adult population size is unknown but certainly exceeds 10,000 and likely is at least several 10,000s. Total population size of the Sonoma County distinct population segment is unknown (USFWS 2003).

Number of Occurrences with Good Viability/Integrity: Unknown
Viability/Integrity Comments: The number of sites with good viability is unknown.

Overall Threat Impact: High
Overall Threat Impact Comments: Most of the remaining range, including population strongholds in eastern Alameda and Contra Costa counties and areas south and west of Millerton Lake in Madera and Fresno counties, is imminently threatened by urban development, conversion of natural habitat to agriculture, introduction of exotic predatory animals (bullfrogs, crayfish, various fishes) that temporarily may occupy salamander breeding habitat, and/or other anthropogenic factors (e.g., rodent control programs, vehicular-related mortality). Reduced ground squirrel populations may reduce the availability of burrows, which are important habitat during the dry season. Use of pesticides for mosquito abatement may reduce food resources for salamanders. Introduction of non-native tiger salamanders may harm populations through hybridization and/or competition. Contaminated runoff from roads may adversely affect salamanders in breeding sites. Chytrid fungus (associated with decline of other amphibian species) has been identified in this species (Santa Clara County), but the infection was not reported as being associated with a die-off (Padgett-Flohr and Longcore 2005). Localities in the Diablo Range, inner Coast Ranges, and Sierra Nevada foothills are not significantly threatened at the present time, and there is a relatively large number of remaining breeding localities.

In Santa Barbara County, plans to convert remaining breeding areas from grazing to intensive agriculture are being developed and implemented (USFWS 2000). Five of the six existing habitat complexes supporting this population suffered moderate to severe levels of habitat destruction or degradation between 1996 and 2000 (USFWS 2000). See USFWS (2000) for further information on threats to the Santa Barbara County population.

Sonoma County population: Primary threat is continuing habitat destruction, degradation, and fragmentation. Reduction in the extent and amount of suitable water bodies, grasslands, and other suitable upland habitats likely has eliminated connectivity among most of the breeding sites, making recolonization of some sites following local extinction more difficult. In addition, habitat reduction lowers the quality of the remaining habitat, by reducing the amount of food, rodent burrows, and other resources (USFWS 2002). Plans to construct a residential development will result in the loss of one of the seven remaining breeding sites and severely impact and further isolate another two of the remaining breeding sites. Because these losses constitute an emergency posing a significant and imminent risk to the well-being of the Sonoma County Distinct Population Segment, USFWS (2002) found that emergency listing was necessary. Secondary threats exist from predation and competition from introduced exotic species; possible commercial overutilization; disease; hybridization with non-native salamanders; various chemical contaminants; road-crossing mortality; rodent control operations, and the species' small remaining population (USFWS 2003). The various primary and secondary threats are not currently being offset by existing Federal, State, or local regulatory mechanisms. The Sonoma County California tiger salamander also is vulnerable to chance environmental or demographic events, to which small populations are particularly vulnerable. The combination of its biology and specific habitat requirements makes the animal highly susceptible to random events, such as drought, disease, and other occurrences. Such events are not usually a concern until the number of breeding/estivation sites or geographic distribution become severely limited, as is the case with the Sonoma County California tiger salamander (USFWS 2003). Predation and competition by introduced or non-native species potentially affects all of the known Sonoma County California tiger salamander breeding sites (USFWS 2002). USFWS (2003) discussed hybridization with non-native tiger salamanders (A. tigrinum)--documented as occurring elsewhere in the range of A. californiense--as a potential threat to this population. See USFWS (2002, 2003) for further discussion of potential threats.

Short-term Trend: Decline of <30% to relatively stable
Short-term Trend Comments: Studies cited by USFWS (2004) indicate that losses of vernal pool habitat (the natural breeding habitat of this species) were about 1.5% annually in the 1980s and 1990s and likely will continue at a similar rate. Assuming a generation time of 8 years (generation time is the average age of parents of the current cohort), the breeding habitat decline (and consequently the population decline) would be roughly 36% over three generations (24 years; see IUCN Red List criteria). Additional reductions due to hybridization, effects of non-native species, and other factors (see USFWS 2004) would increase the extent of population reduction. Hence, a recent/ongoing population reduction of more than 30% over three generations would not be an unreasonable projection.

In Santa Barbara County, of 14 documented breeding sites, half have been destroyed or have suffered severe degradation since mid-1999 (USFWS 2000).

Sonoma County population: in the past two years, four breeding sites have been destroyed or have suffered severe degradation; only seven remain (USFWS 2002).

Long-term Trend: Decline of 30-70%
Long-term Trend Comments: Eliminated from 55-58% of historical breeding sites; reportedly about 75% of the historical vernal pool breeding habitat has been lost (Holland 1998) (though some question the reliability of this estimate).

Intrinsic Vulnerability: Moderately vulnerable
Intrinsic Vulnerability Comments: Populations can recover from drastic declines over a period of a few years, with high recruitment of juveniles. Given normal dispersal distances (see occurrence specifications), recolonization of habitats from which extirpated may be slow to absent if nearby populations within about 0.5-1 km are also extirpated.

USFWS (2002) reported the following: Lifetime reproductive success is low. Trenham (1998) found the average female bred 1.3 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. One of the reasons for the low reproductive success is because individuals do not breed until they are 4 to 6 years old. While individuals may survive for more than 10 years, many may breed only once, and, in some populations, less than 5
percent of marked juveniles survive to become breeding adults (Trenham 1998). With such low
recruitment, isolated populations can decline greatly from unusual, randomly occurring natural events as well as from human-caused factors that reduce breeding success and individual survival. Factors that repeatedly lower breeding success in isolated ponds that are too far from other ponds for migrating individuals to replenish the population can quickly extirpate a population.

Environmental Specificity: Narrow. Specialist or community with key requirements common.
Environmental Specificity Comments: Species is a generalist with respect to terrestrial habitats, but reproduction is largely dependent on fishless bodies of water.

Other NatureServe Conservation Status Information

Distribution
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Global Range: (20,000-200,000 square km (about 8000-80,000 square miles)) Discontinuous distribution in west-central California: coast ranges between Sonoma and Santa Barbara counties, Central Valley and surrounding foothills from southern Colusa County to northwestern Kern County on the west side of the valley and southern Butte County to northern Tulare County on the east side.

This species has been eliminated from much of the historical range in the Central Valley as a result of agricultural and urban development (Stebbins 1985), but it still occurs throughout most of overall historical range and can be locally common (Trenham et al. 2000). About 80% of all extant occurrences are in Alameda, Contra Costa, Madera, Merced, Monterey, San Benito, ad Santa Clara counties, with 30% of all occurrences in Alameda County. Recently rediscovered on the San Francisco Peninsula (Lagunita Lake, Stanford University) (Barry and Shaffer 1994). See Jennings (1996, Herpetological Review 27:147) for an old record from San Mateo County. Elevational range from near sea level to 1054 m.

The Sonoma County population is geographically separated from the closest populations (in Contra Costa, Yolo, and Solano counties) by the Coast Range, Napa River, and the Carquinez Straits, a distance of about 72 km. This population occurs on the Santa Rosa Plain, an area of about 6.8 x 4.4 km (USFWS 2002). The historical range may have included the Petaluma River watershed, as there is one record of a specimen from the vicinity of Petaluma from the mid-1900s (Borland 1856, cited by Storer 1925).

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
Endemism: endemic to a single state or province

U.S. & Canada State/Province Distribution
United States CA

Range Map
Note: Range depicted for New World only. The scale of the maps may cause narrow coastal ranges or ranges on small islands not to appear. Not all vagrant or small disjunct occurrences are depicted. For migratory birds, some individuals occur outside of the passage migrant range depicted. For information on how to obtain shapefiles of species ranges see our Species Mapping pages at www.natureserve.org/conservation-tools/data-maps-tools.

Range Map Compilers: IUCN, Conservation International, NatureServe, and collaborators, 2004


U.S. Distribution by County Help
State County Name (FIPS Code)
CA Alameda (06001), Amador (06005), Butte (06007)*, Calaveras (06009), Contra Costa (06013), Fresno (06019), Kern (06029)*, Kings (06031), Madera (06039), Marin (06041)*, Mariposa (06043), Merced (06047), Monterey (06053), Sacramento (06067), San Benito (06069), San Joaquin (06077), San Luis Obispo (06079), San Mateo (06081), Santa Barbara (06083), Santa Clara (06085), Santa Cruz (06087), Solano (06095), Sonoma (06097), Stanislaus (06099), Sutter (06101)*, Tulare (06107), Tuolumne (06109), Yolo (06113)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
18 Gualala-Salmon (18010109)+, Russian (18010110)+, Sacramento-Stone Corral (18020104)+, Upper Cache (18020116)+, Butte Creek (18020158)+*, Honcut Headwaters-Lower Feather (18020159)+*, Lower Sacramento (18020163)+, Upper Kaweah (18030007)+, Upper Dry (18030009)+, Tulare-Buena Vista Lakes (18030012)+, Middle San Joaquin-Lower (18040001)+, Middle San Joaquin-Lower (18040002)+, San Joaquin Delta (18040003)+, Upper San Joaquin (18040006)+, Upper Chowchilla-Upper Fresno (18040007)+, Upper Merced (18040008)+, Upper Tuolumne (18040009)+, Upper Stanislaus (18040010)+, Upper Calaveras (18040011)+, Upper Mokelumne (18040012)+, Upper Cosumnes (18040013)+, Panoche-San Luis Reservoir (18040014)+, Rock Creek-French Camp Slough (18040051)+, Suisun Bay (18050001)+, San Pablo Bay (18050002)+, Coyote (18050003)+, San Francisco Bay (18050004)+, Tomales-Drake Bays (18050005)+*, San Lorenzo-Soquel (18060001)+, Pajaro (18060002)+, Estrella (18060004)+, Salinas (18060005)+, Central Coastal (18060006)+, Santa Maria (18060008)+, San Antonio (18060009)+, Santa Ynez (18060010)+, Alisal-Elkhorn Sloughs (18060011)+, Carmel (18060012)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A robust salamander.
General Description: Adults are black with large pale yellow spots mainly in the dorsolateral regions, sometimes with a prominent cream band on the lower sides, usually 12 costal grooves, a broad head, small eyes, and tubercles on the soles of the feet; pond-type larva (but lacks balancers), with three large pairs of gills, vomerine teeth in U-shaped pattern, and dorsal fin extending to region of axilla; adults usually are about 15-22 cm in total length (Stebbins 1951, 1985; Behler and King 1979).
Diagnostic Characteristics: The following pertains to metamorphosed adults. Differs from A. MACRODACTYLUM in lacking a distinct dorsal stripe or stripelike row of spots. Differs from A. GRACILE in having distinct dorsal markings and tubercles on the underside of the feet and by lacking parotoid glands and a glandular ridge on the tail. Differs from plethodontid salamanders in lacking a nasolabial groove. Differs from other subspecies primarily in color pattern.
Reproduction Comments: Breeding occurs mainly December-February, after rains fill pools and ponds. Fertilization internal. Eggs are laid singly or in small clusters, hatch in 2-4 weeks. Larvae transform in about 4 months (Behler and King 1979), as water recedes in late spring or summer, but larvae may overwinter in permanent ponds (Alvarez 2004). May not breed in drought years when ponds fail to fill. Production of metamorphs tends to be "boom or bust" at a given site (Loredo and Van Vuren 1996).

In a pond in Monterey County, most individuals matured sexually at 4-5 years, but less than 50 percent returned to breed a second time; numbers of breeding adults varied by more than a factor of four over several years, and annual juvenile production ranged from 121-775 metamorphs. This level of reproduction indicated that the population was a reproductive sink during the period of the study (Trenham et al. 2000).

Ecology Comments: See Holland et al. (1990) for a description of late summer overland movements of juveniles and mass mortality of newly metamorphosed individuals.
Non-Migrant: N
Locally Migrant: Y
Long Distance Migrant: N
Mobility and Migration Comments: Migrates up to about 2 km between terrestrial habitat and breeding pond (S. Sweet, cited by USFWS 2002); rain storms precede major migrations to the breeding sites, with most migration on rainy nights.

During the first night's emigration from a breeding pond, individuals moved up to 129 m from the pond; most moved less than 80 m; total distance moved on subsequent nights were not determined (Loredo et al. 1996). For 8 radio-tagged individuals followed for up to 4 months, Trenham (2001) found that the maximum distance moved from the breeding pond was 248 m (mean = 94 m).

Juveniles have been observed to migrate up to 1.6 km from breeding ponds to estivation areas (Austin and Shaffer 1992).

Migrations may occur from November through April (Holland et al. 1990).

Lacustrine Habitat(s): Shallow water
Palustrine Habitat(s): HERBACEOUS WETLAND, TEMPORARY POOL
Terrestrial Habitat(s): Grassland/herbaceous, Savanna, Woodland - Hardwood
Special Habitat Factors: Benthic, Burrowing in or using soil
Habitat Comments: Lives in vacant or mammal-occupied burrows (e.g., California ground squirrel, valley pocker gopher) (Trenham 2001), occasionally other underground retreats, throughout most of the year; in grassland, savanna, or open woodland habitats. Sonoma County populations is closely associated with the presence of gopher burrows (see USFWS 2003). Lays eggs on submerged stems and leaves, in shallow ephemeral or semipermanent pools and ponds that fill during heavy winter rains or in permanent ponds (Alvarez 2004); adults spend little time in breeding sites.
Adult Food Habits: Carnivore, Invertivore
Immature Food Habits: Carnivore, Invertivore
Food Comments: Larvae eat various aquatic invertebrates and amphibian larvae. Adults eat terrestrial invertebrates and sometimes small vertebrates.
Adult Phenology: Hibernates/aestivates, Nocturnal
Immature Phenology: Hibernates/aestivates, Nocturnal
Phenology Comments: Inactive in cold or hot temperatures. Adults remain in underground burrows or crevices for much of the year, but they emerge to breed during the rainy season.
Colonial Breeder: Y
Length: 22 centimeters
Economic Attributes Not yet assessed
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Management Summary
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Preserve Selection & Design Considerations: Isolated breeding ponds may be insufficient for long-term maintenance of viable populations (Trenham et al. 2000).
Management Requirements: For the Lagunita population at Stanford University, Barry and Shaffer (1994) recommended construction of a drift fence and tunnel system to divert migrating adults and juveniles underneath the highway, maintenance of water levels through mid-summer to allow most larvae to complete metamorphosis, and excavation of sumps in the lake bed to entrap larvae and keep them from being swept down the lake drain.
Monitoring Requirements: See Alvarez (2004) for information on use of an artificial egg laying substrate to detect the presence of this species.
Population/Occurrence Delineation
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Group Name: Ambystomatid Salamanders

Use Class: Not applicable
Minimum Criteria for an Occurrence: Occurrences are based on evidence of historical presence, or current and likely recurring presence, at a given location. Such evidence minimally includes collection or reliable observation and documentation of one or more individuals (including larvae or eggs) in or near appropriate habitat where the species is presumed to be established and breeding.
Separation Barriers: Heavily traveled road, especially at night during salamander breeding season, such that salamanders almost never successfully traverse the road; road with a barrier that is impermeable to salamanders; wide, fast rivers; areas of intensive development dominated by buildings and pavement.
Separation Distance for Unsuitable Habitat: 1 km
Separation Distance for Suitable Habitat: 3 km
Separation Justification: BARRIERS/UNSUITABLE HABITAT: Rivers may or may not be effective barriers, depending on stream width and hydrodynamics; identification of streams as barriers is a subjective determination. Bodies of water dominated by predatory fishes have been described as barriers but probably should be regarded as unsuitable habitat. For A. barbouri, a stream-pool breeder, predatory fishes appeared to act as a barrier to larval dispersal and gene flow for populations separated by as little as 500-1000 m (Storfer 1999). Highly disturbed land, such as the cleared and bedded soils of some silvicultural site preparation, may serve as an impediment to movement of A. cingulatum (Means et al. 1996), although Ashton (1998) noted the species' use of pine plantations, pastures, and three-year-old clearcuts. Such areas should be treated as unsuitable habitat rather than barriers.

MOVEMENTS: Palis's (1997b) suggested use of 3.2 km between breeding sites to distinguish breeding populations of A. cingulatum was based on Ashton's (1992) finding that individuals may move as much as 1.6 km from their breeding ponds. Ambystoma californiense sometimes migrates up to 2 km between breeding ponds and terrestrial habitat (see USFWS 2004). Funk and Dunlap (1999) found that A. macrodactylum managed to recolonize lakes after trout extirpation despite evidence of low levels of interpopulation dispersal. Based on a review of several Ambystoma species (e.g., Semlitsch 1981, Douglas and Monroe 1981, Kleeberger and Werner 1983, Madison 1997), Semlitsch (1998) concluded that a radius of less than 200 meters around a breeding pond would likely encompass the terrestrial habitat used by more than 95 percent of adults. Faccio's (2003) study of radio-tagged A. maculatum and A. jeffersonianum in Vermont supports this conclusion. In New York, all movements of A. tigrinum occurred in areas within 300 m of the nearest breeding pond (Madison and Farrand 1998). However, most studies of these salamanders had small sample sizes and/or were not designed to detect long-distance movements, so migration distance may be somewhat underestimated.

In summary, ambystomatid salamanders generally stay within a few hundred meters of their breeding pool. Due to high breeding site fidelity and limitation of breeding to pool basins, populations using different breeding sites exhibit little or no interbreeding among adults. Thus one might argue that each pool constitutes a separate occurrence or that the separation distance for suitable habitat should be the nominal minimum of 1 km. However, little is known about how frequently first-time (or experienced) breeders use non-natal pools (pools from which they did not originate) or how far they may move to such sites. Frequent colonization of new and remote habitats by at least some species suggests that dispersal movements sometimes may be longer than typical adult migration distances. It seems unlikely that locations separated by a gap of less than a few kilometers of suitable habitat would represent independent occurrences over the long term.

Inferred Minimum Extent of Habitat Use (when actual extent is unknown): .3 km
Inferred Minimum Extent Justification: Inferred extent distance pertains to breeding sites (with the center of the circle in the center of the breeding site). Most ambystomatids stay within a few hundred meters of their breeding pool (see separation justification section).
Date: 10Sep2004
Author: Hammerson, G.
Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 04Apr2011
NatureServe Conservation Status Factors Author: Hammerson, G.
Element Ecology & Life History Edition Date: 27Apr2005
Element Ecology & Life History Author(s): Hammerson, G.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
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  • Alvarez, J. A. 2004a. Use of artificial egg laying substrate to detect California tiger salamanders (Ambystoma californiense). Herpetological Review 35:45-46.

  • Alvarez, J. A. 2004b. Overwintering California tiger salamander (Ambystoma californiense) larvae. Herpetological Review 35:344.

  • Austin, C. C. and H. B. Shaffer 1992. Short, medium, and long-term repeatability of locomotor performance in the tiger salamander, Ambystoma californiense. Functional Ecology 6(2):145-153.

  • Barry, S. J., and H. B. Shaffer. 1994. The status of the California tiger salamander (AMBYSTOMA CALIFORNIENSE) at Lagunita: a 50-year update. Journal of Herpetology 28:159-164.

  • Behler, J. L., and F. W. King. 1979. The Audubon Society field guide to North American reptiles and amphibians. Alfred A. Knopf, New York. 719 pp.

  • Blackburn, L., P. Nanjappa, and M. J. Lannoo. 2001. An Atlas of the Distribution of U.S. Amphibians. Copyright, Ball State University, Muncie, Indiana, USA.

  • Collins, J. T. 1990. Standard common and current scientific names for North American amphibians and reptiles. 3rd ed. Society for the Study of Amphibians and Reptiles. Herpetological Circular No. 19. 41 pp.

  • Davidson, C., H. B. Shaffer, and M. R. Jennings. 2002. Spatial tests of the pesticide drift, habitat destruction, UV-B, and climate-change hypotheses for California amphibian declines. Conservation Biology 16:1588-1601.

  • Holland, D. C., M. P. Hayes, and E. McMillan. 1990. Late summer movement and mass mortality in the California tiger salamander (AMBYSTOMA CALIFORNIENSE). Southwestern Naturalist 35:217-220.

  • Holland, R. F. 1998. Great Valley vernal pool distribution, photorevised. Pages 71-75 in C. W. Witham et al., editors. Ecology, conservation, and management of vernal pool ecosystems. California Native Plant Society, Sacramento.

  • Kraus, F. 1988. An empirical evaluation of the use of the ontogeny polarization criterion in phylogenetic inference. Systematic Zoology 37:106-141.

  • Loredo, I., D. Van Vuren, and M. L. Morrison. 1996. Habitat use and migration of the California tiger salamander. Journal of Herpetology 30:282-285.

  • Loredo, I., and D. Van Vuren. 1996. Reproductive ecology of a population of the California tiger salamander. Copeia 1996:895-901.

  • NatureServe. Central Databases. Arlington, Virginia. U.S.A. Online. Available: http://www.natureserve.org/explorer/

  • Padgett-Flohr, G. E., and J. E. Longcore. 2005. Ambystoma californiense. Fungal infection. Herpetological Review 36:50-51.

  • Shaffer, H. B., J. M. Clark, and F. Kraus. 1991. When molecules and morphology clash: a phylogenetic analysis of the North American ambystomatid salamanders (Caudata: Ambystomatidae). Systematic Zoology 40:284-303.

  • Shaffer, H. B., R. N. Fisher, and S. E. Stanley. 1993. Status report: the California tiger salamander (AMBYSTOMA CALIFORNIENSE). Final report to the California Department of Fish and Game.

  • Stebbins, R. C. 1985a. A field guide to western reptiles and amphibians. Second edition. Houghton Mifflin Company, Boston, Massachusetts. xiv + 336 pp.

  • Storer, T. I. 1925. A synopsis of the Amphibia of California. University of California Publications in Zoology 27:1-342.

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