California giant salamander

The Pacific giant salamander (D.ensatus) was thought to consist of three geographic populations: an Idaho group, a group in northern California, and a group in Oregon and Washington. In 1989 genetic studies showed that the D.ensatus populations consisted of three species: the Idaho giant salamander (D.aterrimus) in Idaho, and two highly divergent species with a narrow hybrid zone in California, the coastal giant salamander (D.tenebrosus) (ranging from northern California to Washington) and the California giant salamander (D.ensatus) (ranging from Santa Cruz County to Mendocino County). A fourth species of Dicamptodon, Cope's giant salamander (D.copei), lives on the Olympic Peninsula, Washington. ==Distribution and habitat==

Geographic range The California giant salamander is endemic to Northern California and lives up to primarily in damp, coastal forests including coast Douglas fir (Pseudotsuga menziesii var. menziesii) and California coast redwood (Sequoia sempervirens) in both montane and valley-foothill riparian habitats. They tend to be common where they occur. The adult terrestrial form is found under surface litter and in tunnels, while the adult aquatic and larval forms are found mainly in cool, rocky streams and occasionally in lakes and ponds. It is found in two (possibly three) isolated regions. The first range includes Sonoma, Napa, and Marin Counties, southwestern Lake County, western Glenn County, and southern Mendocino County. The other documented region is south of the San Francisco Bay from central San Mateo County to southern Santa Cruz County plus western Santa Clara County. The California giant salamander does not occur in the East Bay, forming a gap between these two populations. There is an unconfirmed sight record from Big Sur in Monterey County, approximately 75 miles (100 km) to the south of the documented population in the Santa Cruz area. Adult salamanders were found near deteriorating waterway infrastructure, however more research is needed to be determine if this is a preferred habitat. ==Description==

The adult California giant salamander can reach in total length (including tail). ==Behavior and ecology==

Activity The California giant salamander is predominantly nocturnal. Aquatic adults and larvae eat aquatic invertebrates, fish, snakes, and other amphibians. Predators The California giant salamander is preyed upon by the American water shrew (Sorex palustris) and the Sierra garter snake (Thamnophis couchi). ==Reproduction and development==

Breeding The California giant salamander breeds from March to May, with egg-laying peaking in May. Some occurrences of breeding in autumn have been reported. Both seasons have extremely maintained wet conditions, which are important for sexually mature adults. Terrestrial adults will migrate out from under rocks and logs to find puddles and streams to find mates. Reproduction Reproduction of California giant salamanders are observed to be in aquatic environments like small puddles and fresh water streams. Mothers will guard their egg clutch for months until they hatch, to protect from predation. Egg deposition Fresh California giant salamander eggs are white and are smaller than . Eggs are concealed several feet below the surface in cold, slowly flowing water often beneath rocks and coarse woody debris in stream bottoms. Larval stage Once hatched in water, the larval stage of the life cycle begins where California giant salamanders grow approximately half an inch per month in the best conditions. Larvae typically lose their external gills and transform to terrestrial adults after 1 to 2 years. In permanently perennial streams, adults may retain their gills and become aquatic adults. Neotenes Some California giant salamander larvae exhibit neoteny, continuing to grow into adults and become sexually mature without losing their external gills. Adult-sized neotenes have a uniform brown coloring on their heads, sides, and backs with retained external gills which allow them to live in perennial streams as aquatic adults. ==Diseases and threats==

Disease has been known to lead to significant mortalities of the California giant salamander. In 2021, California Department of Fish and Wildlife observed poor body conditions and skin lesions on individuals at multiple sites due to parasitic infections. ==References==