The California tiger salamander (Ambystoma californiense) is an important part of California's precious natural heritage. This amphibian was historically distributed throughout most of the Central Valley, adjacent foothills, Coast Ranges, Santa Barbara County, and the Santa Rosa Plain in Sonoma County. This California tiger salamander requires seasonal ponds, or vernal pools, for successful breeding. The species breeds during the winter rainy season, but spends the majority of the year in underground refuges, primarily small mammal burrows, in grassland or oak woodland habitat.

California tiger salamander: Frank Scheicher 1994

Due to its unique biology and life history, the CTS is extremely vulnerable to habitat destruction, modification, and fragmentation by human activities. All CTS subpopulations statewide face a high to extreme degree of threat from the physical elimination of habitat primarily due to urban and agricultural development. The species is also threatened by a number of other factors including habitat fragmentation, hybridization with non-native tiger salamanders, introduced diseases, and predation by other non-native introduced species.

The habitat types the California tiger salamander requires, vernal pools, grasslands, and oak woodlands, are some of the most endangered habitat types in California. It has been estimated that less than one tenth of one percent of California's native grasslands remain, and approximately 95% of California's vernal pool landscape has already been lost. Available habitat for the species throughout its range has been eliminated in recent decades by at least 75%. The remaining core area for the species is the Livermore Valley area in the East Bay, which has undergone explosive urban development in recent years. Ongoing research by the Center for Biological Diversity has found at least 118 development projects in some stage of development in occupied or suitable habitat for the species.

The Center has advocated tirelessly to gain protection for the California tiger salamander at both the federal and state level. The Center has filed petitions and lawsuits to add the species to both the federal and California endangered species lists.

Most recently, the Center, along with our partners Environmental Defense Center, Defenders of Wildlife, Sierra Club Sonoma Group, Citizens for a Sustainable Cotati,, Citizen's Committee to Complete the Refuge, Butte Environmental Center, and Ohlone Audubon Society petitioned the California Fish & Game Commission to list the species under the California Endangered Species Act. Under state law, the Commission must refer the Petition to the Department of Fish and Game ("CDFG") for a finding as to whether the listing is warranted. CDFG must make a recommendation within 90 days of receipt of the petition, and the Fish & Game Commission will make the final determination shortly thereafter.

In June 2001, the Center petitioned the U.S. Fish & Wildlife Service to list the Sonoma County population of the California tiger salamander under the federal Endangered Species Act on an emergency basis as a distinct population segment, or "DPS." When the Service failed to respond, the Center filed a suit in U.S. District Court which resulted in the emergency and final listing of the Sonoma County California tiger salamander as endangered, as well as the May 23, 2003 proposed rule to list the species as threatened throughout its remaining range. The Service must make a final determination on the proposal by May 15, 2004.

Photo taken near Santa Rosa, California by Gerald and Buff Corsi, © 1999 California Academy of Science (415) 750-7122
Adult. Sonoma County population of the California tiger salamander. Photo taken near Santa Rosa, California by Gerald and Buff Corsi, 1999 California Academy of Science (415) 750-7122.

On January 16, 2004, the Service proposed critical habitat for the Santa Barbara population of the California tiger salamander in response to a separate suit by the Center and the Environmental Defense Center. The Santa Barbara California tiger salamander has been listed as federally endangered since 2000.

Natural History

Adult California tiger salamanders migrate to breeding pools on rainy nights in early winter. The number of eggs laid by a single female ranges from approximately 400 to 1,300 per breeding season. Eggs hatch in 10 to14 days, and larvae feed on algae, small crustaceans, and mosquito larvae for about 6 weeks after hatching, when they switch to larger prey. Larger larvae will consume smaller tadpoles of Pacific treefrogs (Hyla regilla), California red-legged frogs (Rana aurora draytonii), western toads (Bufo boreas), and spadefoot toads (Scaphiopus hammondii), as well as many aquatic insects and other aquatic invertebrates.

California tiger salamanders usually do not breed for the first time until they reach 4 to 6 years of age. Less than fifty percent of California tiger salamanders breed more than once in their lifetime. In very dry years, breeding may not take place at all.
The California tiger salamander breeds primarily in vernal pools and swales, unique ecosystems that fill with winter rains and dry completely by summer. The California tiger salamander spends most of its lifecycle estivating underground in adjacent valley oak woodland or grassland habitat, primarily in abandoned rodent burrows. Research has shown that dispersing juveniles can roam up to two miles from their breeding ponds and that a minimum of several hundred acres of uplands habitat is needed surrounding a breeding pond in order for the species to survive over the long term. Reserves of multiple breeding ponds surrounded by 1000 acres or more of habitat are recommended to ensure the persistence of the species.

graphic Andrew Rodman ©2002
January 29, 2004
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