Ambystoma californiense (Gray, 1853) California Tiger Salamander
(A.
californiense gallery)
The California Tiger Salamander is a large,
robust salamander, with striking coloration and pattern. This species is endemic to California, where its
habitat has become highly fragmented due to encroaching human
development. Currently, Ambystoma californiense is on the endangered
species list in some counties, a status that developers often dispute in
court. Urban developers would like the status lowered to threatened, so
that development can commence in some instances. Such encroachment would
have detrimental effects on the survival of this wonderful
species...
Physical Description
 Ambystoma californiense are glossy black dorsally, with
irregular white or bright yellow
spots or bars along the dorsum, tail, and limbs.
The ventral area is light gray, and may also have a few smaller, lighter colored spots scattered about.
Spots and bars are usually absent or minimal around the middle of the
back. Santa Barbara populations, which are considered a distinct species
by some, tend to possess more lateral bars than spots, and often have a
cream-yellow bar on the flanks. Adults usually possess 12 costal
grooves, and may grow to 3-5 inches SV (snout to vent length). The generally
body form greatly resembles other tiger American tiger salamanders (A.
mavortium, A. tigrinum), but the head is flatter in profile. Adult males have longer tails and are slightly larger than the females. Adults
and juveniles are fossorial, and are rarely seen above ground (except during the breeding season).
This species possesses tubercles on feet, and pinkish toes.
Ambystoma californiense was at one time considered to be a subspecies of A. tigrinum,
now A. mavortium. However, because of its
geographical isolation from A. mavortium, difference in coloration, and recent genetic comparisons, this
theory is not widely accepted today, and A. californiense is treated as a
separate species by most. However, A. tigrinum/mavortium readily
hybridize with A. californiense where foreign populations have
been introduced.
Distribution & Natural Habitat
 Ambystoma californiense inhabits subterranean areas near ponds in
grasslands, or woodlands of the Central Valley of California, USA, and lower
elevations west of Central Valley. Populations can be found west
of the Sierra Nevada between Sonoma and Santa Barbara counties, California. Distribution is
highly fragmented, with 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. A. californiense is still found throughout
much of its historical
range, although most populations are now extinct in the Central Valley.
Populations are
 concentrated in northern range, in the counties of Alameda,
Contra Costa, Madera, Merced, Monterey, San Benito, Sonoma, San Mateo, and Santa Clara, with
populations in Alameda County accounting for 30% of the total estimated number
in existence. Other populations or single occurrences have been reported to exist in the counties of
Sacramento, Solano, Tulare, Kern, and Yolo, and single occurrences have
been reported in the counties of Sutter, and Riverside. A. californiense has been re-discovered on the San
Francisco Peninsula, where it was thought to have vanished (Barry and Shaffer,
1994). Common habitats include oak savanna, grassland, and the edges of woodland and
low elevation coniferous forests (Stebbins, 2003). Outside of the breeding
season, adult and juvenile A. californiense are thought so spend the their time in
aestivation in underground in burrows excavated by other animals, such as ground squirrels and
gophers, or in moist soil crevices. However, recent studies have indicated A.
californiense may actually remain active outside of the breeding
season, moving from burrow to burrow (USFWS, 2004).
Aquatic habitats are typically vernal pools
that may diminish by the end of summer. Most individuals return to the same
pools each year, and so breeding relies on these pools developing each year.
Some may also breed in in permanent ponds or the sluggish areas of streams.
Breeding
California Tiger Salamanders migrate to and from breeding ponds from November through April, with most of the mating
occurring between
December and March (Petranka, 1998). Adults can be seen on the surface as early as the first fall
rains. Breeding ponds are typically temporary pools that form consistently each
year. Some may also breed in sluggish streams or ponds. Adults are explosive breeders, as they may only encounter a few rainy nights the whole season.Courtship may consist of the male nudging the females cloaca in a similar manner as Ambystoma
tigrinum, prior to depositing
a spermatophore. The female will usually attach the eggs singly to twigs, grass stems, and other vegetation. The eggs are
approximately 2mm in diameter, and will hatch within 2-4 weeks. Females in the
East Bay areas may lay eggs twice in one season, once in December and again the
following February (USFWS, 2004).
The larval stage last approximately 3-6 months, before metamorphose occurs just
before, or during the dry summer season. Some larvae from Contra Costa Co. and
Alameda Co. may remain aquatic through the summer season (USFWS, 2004). It is
thought that A. californiense are incapable of expressing paedomorphic
traits, due to the fact that they rely on temporary pools for breeding purposes
(USFWS, 2004). Upon metamorphosis, the juveniles will
leave the ponds and seek out crevices and holes to reside in. Although they are capable of burrowing small holes in moist soil, most
will move into abandoned and active squirrel or gopher holes (Petranka 47). Sexual maturity
is reached around 4-5 years (USFWS, 2004).
Conservation Status
For conservation purposes, the U.S. Fish and Wildlife Service distinguishes
between populations found in the central area of the entire range, Santa
Barbara Co., and Sonoma Co. In 2004, the status of all populations were
ruled Threatened, including the Sonoma and Santa Barbara County
populations, which were previously listed as Endangered. The USFWS has
published a proposal to designate critical habitats for the central
populations in 20 counties. This new conservation status stems from
studies showing an increase in converted grazing land, which may be used
for migration and breeding purposes by A. californiense, and
projected lower rates of habitat conversion into intensive
agriculture.
Urban encroachment seems to be the main cause of population declines, whether
direct or indirect. No matter the legal status of A. californiense,
the fact is these animals are disappearing, mainly from direct human
encroachment. Fortunately, recovery plans are proposed often, that when
put into action further protect A. californiense populations. For more specific information about
current status, description, and recovery plans, see the
US
Fish and Wildlife Service Ambystoma californiense page, and the
Sacramento
Fish & Wildlife Office Species Account. |
Threats
The main threats to A. californiense are habitat loss and
fragmentation due to human encroachment. A. californiense has lost roughly 55-58% of its historic breeding sites. This
figure is controversial, and has also been estimated at 75%. Habitats in the Diablo Range, inner Coast Ranges, and Sierra Nevada area are the
least threatened populations, with a considerable number of individuals still
existent in breeding locations. The habitats of Alameda and Contra Costa counties, and the areas near
Millerton Lake in Madera and Fresno counties are imminently threatened
by urban and agricultural development, and the introduction of predatory animals, such as
bullfrogs and crayfish. The introduction of foreign tiger salamander
species has also played a role in the decline of A. californiense
populations. In Monterey and and San Benito Co., in particular, extensive
hybridization has occurred between the local populations and introduced A.
tigrinum. In these areas, nearly all populations consist of hybrids today (Stebbins,
2003). A. tigrinum larvae are sometimes used as fish bait. Inevitable
escapees probably account for the origin of the introduced A. tigrinum.
The sale of of A. tigrinum for use as bait has since been outlawed in
California.
Other population threats are the use of pesticides, which
can poison
the existing populations as well as wipe out their insect food supply, vehicular
mortalities, reduced ground squirrel populations (A. californiense often
occupy ground squirrel burrows), drainage of wetlands,
introduction of fish or bullfrogs, and contaminated runoff from roads.
Misc. Notes
Ambystoma californiense was at one time considered to be a subspecies of A. tigrinum,
now A. mavortium. However, because of its
geographical isolation from A. mavortium, difference in coloration, and recent genetic comparisons, this
theory is not widely accepted (Petranka 47).
"USFWS (2000) reviewed the biogeographical and genetic information supporting the
recognition of the Santa Barbara County population as a distinct population
segment under the U.S. Endangered Species Act (Nature Serve Explorer)."
References
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.
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.
U.S. Fish and Wildlife Service (USFWS). 13 June 2002. Review of species that
are candidates or proposed for listing as endangered or threatened; annual
notice of findings on recycled petitions; annual description of progress on
listing actions. Federal Register 67(114): 40657-40679.
U.S. Fish and Wildlife Service (USFWS). 19 January 2000. Emergency rule to
list the Santa Barbara County distinct population of the California tiger
salamander as endangered. Federal Register 65(12):3096-3109. Proposal to list
the Santa Barbara County distinct population of the California tiger salamander
as endangered. Federal Register 65(12): 3110-3111.
U.S. Fish and Wildlife Service (USFWS). 21 September 2000. Final rule to list
the Santa Barbara County distinct population of the California tiger salamander
as endangered. Federal Register 65(184): 57242-57264.
U.S. Fish and Wildlife Service (USFWS). 22 July 2002. Listing the Sonoma
County distinct population segment of the California tiger salamander as
endangered. Federal Register 67(140): 47726-47740.
U.S. Fish and Wildlife Service (USFWS). 22 July 2002. Listing the Sonoma
County distinct population segment of the California tiger salamander as
endangered. Federal Register 67(140): 47758-47760.
U.S. Fish and Wildlife Service (USFWS). 04 August 2004. Endangered and
threatened wildlife and plants; determination of threatened status for the
California Tiger Salamander; and special rule exemption for existing routine
ranching activities; final rule. Federal Register 69(149): 47212-47248.
Behler, John L., and F. Wayne King. National Audubon Society Field Guide to North American Reptiles and Amphibians.
New York: Knopf, 1979, 1996.
Petranka, James W. Salamanders of the United States and Canada.
Smithsonian Institution Press, 1998.
Stebbins, Robert C. Western Reptiles and Amphibians (third edition).
Houghton Mifflin Company, 2003.
LaMonte, Greg, and Meredith J. Mahoney. (2002). Ambystoma californiense,
California Tiger Salamander. AmphibiaWeb.
http://elib.cs.berkeley.edu/cgi-bin/amphib...etc.
Animal Diversity Web. (2003).
http://animaldiversity.ummz.umich.edu/.
(Accessed: 2001-2003).
California Tiger Salamander, Ambystoma californiense. (2002). United
States Geological Survey.
http://www.npwrc.usgs.gov/narcam/idguide/acalif.htm
(Accessed: 2002).
California Tiger Salamander. (2003). Center for Biological Diversity.
http://www.sw-center.org/swcbd/species/ctigersal/
(Accessed: 2002).
Center for North American Herpetology. (2003).
http://www.cnah.org/
(Accessed: 2000).
Nature Serve Explorer (Database). Nature Serve.
http://www.natureserve.org/explorer/index.htm
(Accessed: 2000-2003).
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