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, 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 abandoned rodent burrows, in grassland or oak woodland habitat.

The California tiger salamander is on the brink of extinction primarily due to habitat destruction due to urban and agricultural development. 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.

The California tiger salamander is also threatened by other factors such as habitat fragmentation, road mortality, introduced species, and agricultural contaminants. Major projects that threaten the species include the proposed Los Vaqueros Reservoir expansion, the proposed U.C. Merced Campus at the Lake Yosemite site outside of Merced, and the South Sonoma Business Park in Cotati.

In June 2001, the U.S. Fish & Wildlife Service had received several petitions from several watch groups 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." Last year, the U.S. Fish & Wildlife Service listed the Santa Barbara population of the California tiger salamander on an emergency basis as a DPS. The species statewide has been listed as "Warranted but Precluded" by the U.S. Fish & Wildlife since 1994, a designation meaning that the species should be listed but that the agency is precluded from doing so by budget limitations. The Fish & Wildlife Service has consistently failed to request sufficient funds from Congress to run the listing program.

Finally the U.S. Fish & Wildlife Services did decide to change the status of the species for the Sonoma County distinct population segment (DPS) of the California tiger salamander (Ambystoma californiense), under the Endangered Species Act of 1973, as amended (Act). In Sonoma County, the California tiger salamander is imperiled by a variety of factors including habitat destruction, degradation, and fragmentation due to urban development, hybridization with non-native salamanders, inadequate regulatory mechanisms, disease, and pesticide drift. We listed this DPS on an emergency basis on July 22, 2002. The emergency designation expires on March 19, 2003. This rule is effective upon publication in the Federal Register, and implements the Federal protection and recovery provisions afforded by the Act for the Sonoma County DPS of the California tiger salamander. This final rule is being issued as a result of a settlement agreement and consent decree.

Natural History
Adult California tiger salamanders migrate to breeding pools on rainy nights in early winter. The number of eggs laid by single female ranges from approximately 400 to 1,300 per breeding season. Eggs hatch in 10 to 14 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 astivating 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 480 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.