Species of the Week - California Tiger Salamander

By Rachel Shaw | Posted on May 28, 2009

Endemic to the Central Valley, the yellow-and-black California tiger salamander depends on vernal pools and ground squirrel burrows for its survival.

California Tiger Salamander.  Source.

In the rainy winter months, these large salamanders emerge from the burrows of ground squirrels and pocket gophers and migrate in search of vernal pools and slow-moving streams.  Males lead the migration, arriving at the breeding ponds a week or two ahead of the female salamanders.  It is an arduous journey for these animals, as they may travel over a mile at a pace of only 50 meters an hour, and take up to several days to reach their destinations. 

California tiger salamanders are long-lived, with lifespans of about a decade, but they do not reach reproductive maturity until they are four to six years old, and females may breed only once in their lifetime, and only if the conditions are right.  When they are, female salamanders can produce up to 1300 yellow-brown eggs, which they lay in the water and attach to vegetation. 

The hatchlings eat whatever life in the vernal pool they can fit in their mouths: zooplankton, mosquito larvae and algae to begin with; invertebrates and the tadpoles of frogs and toads as they grow larger.  Larval salamanders are grayish yellow or grayish green with feathery gills and broad gills.  They remain in the pools through the spring and into the summer, then transform into their black-and-yellow adult forms as the pools dry up.  Emerging at night, they seek out burrows of their own in which to shelter from the dry heat of summer.  Except for the breeding seasons, adults will spend the rest of their lives in such burrows, eating invertebrates, insects, and the occasional small mammal.

Most of what we know about these salamanders is tied to their breeding cycle, both because this is when they are most visible (though some researchers have begun to use fiber optic cameras to observe them in their shared burrows) and when they are most vulnerable.  The migration exposes them to dehydration and predators such as herons and bullfrogs, neither of which seem much discouraged by the toxins secreted by the salamanders (which may serve primarily to deter their rodent roommates from bothering them). 

Their dependence on vernal pools for reproduction, and the way their biology is tied to the particular seasonal patterns of the Central Valley and nearby grasslands and woodlands, makes this population vulnerable to habitat loss.  California tiger salamanders overall are listed as threatened; two smaller sub-populations in Santa Barbara and Sonoma are listed as endangered.  Habitat fragmentation, predation by the introduced bullfrog, and hybridization with non-native species of tiger salamander are the main threats to these animals.

Sources

Note: Usually I include an image of the featured species, but was unable to find one that was under a Creative Commons or similar license.  If you have a photograph of one of these animals and would like to let us use it here, please let me know.  Thanks, Dave!

In the meantime, images of this appealing animal are easily found by searching for “California tiger salamander.”

Center for Biological Diversity
Wikipedia
California Herps
U.S. Fish and Wildlife Service
Animal Diversity Web
EOL
Tree of Life
Central Valley Vernal Pools
Encyclopedia of Earth article on habitat area