Stanislaus River Basin and Calaveras River Water Use Program
Threatened and Endangered Species Report - March 1995
Bay Delta and Special Water Projects Division, CA Dept. of Fish and Game
California Tiger Salamander
Ambystoma tigrinum californiense
Category 2 Candidate for listing by the U.S. Fish and Wildlife Service and California
Department of Fish and Game "Species of Special Concern"
Life History
The California tiger salamander is a large salamander measuring 7 to 15 inches in length
and is distinguished from other salamanders by spots and bars of white, cream, or yellow on a
black background. This salamander has small eyes, a broad and rounded snout, and tubercles
on the underside of the front and rear feet (Stebbins 1985).
The California tiger salamander typically inhabits grassland and oak woodland habitats
below 1,500 feet which have scattered ponds, intermittent streams, or vernal pools. Shaffer et
al. (1993) determined that pond type, size, and turbidity affected tiger salamander distribution;
vernal pools covering more than 250 square feet with fairly turbid water provide the best
habitat. Additionally, a significant inverse association of California tiger salamanders with
predatory fishes and bullfrogs has been found. The reason is that larval salamander fall prey
to predatory fish and adult bullfrogs, in addition larval bullfrogs compete with salamanders for
food (Shaffer et al. 1993).
Tiger salamanders estivate in rodent burrows throughout the summer and emerge after
the first few sustained rain storms in November. Rainfall is important to the maintenance and
formation of breeding ponds and also triggers adult migration to breeding ponds. Adults will
migrate up to 3,300 feet from estivation sites to breeding ponds. The breeding season extends
from December through February with females laying numerous small clusters of eggs on
submerged and emergent vegetation (Stebbins 1972). Adults remain in breeding ponds for
several days before exiting to forage in terrestrial habitat.
Adult and terrestrial juveniles forage on earthworms, snails, insects, fish, and small
mammals by utilizing sit-and-wait tactics to capture their prey (Lindquist and Bachmann 1980,
Stebbins 1972). Small aquatic larvae forage primarily on zooplankton while larger larvae
forage on zooplankton, amphipods, mollusks, and insect larvae (Dodson and Dodson 1971).
Findings and Conclusions
Current threats to the continued existence of the California tiger salamander include
habitat loss due to increased urbanization, conversion of native grasslands to agriculture,
introduction of predatory fish in known breeding ponds, introduction of bullfrogs, rodent
control which reduces the availability of summer estivation sites, development of roads
between breeding ponds and terrestrial habitats and associated automobile deaths, and the
introduction of other tiger salamander species which could potentially result in genetically
inferior hybrid salamanders.
The Stanislaus River itself is not considered potential habitat because flows are variable
and frequently too heavy to be a reliable breeding area. There is, however, tiger salamander
habitat along the Stanislaus River corridor within the grasslands of all three reaches. One
sighting of this species was recorded in 1975 near the town of Oakdale. More recently,
BioSystems (1994) reported tiger salamander larvae found in several locations north of
Oakdale.
Any project involving the Stanislaus River which affects the adjacent grasslands or open
areas within any of the three reaches could potentially affect this species and further surveys
would be needed.
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