California Tiger Salamander
The Secret Salamander of Mount Diablo
by Michael Marchiano
The California Tiger Salamander, Ambystoma californiense is one of the least observed animals in Mount Diablo State Park. This salamander is exclusively found only in California and is now on both federal and state threatened species list. The tiger salamander is California’s second largest salamander reaching a length of seven to eight inches. Yellow bars and spots adorn a shiny black body of this robust amphibian. Found primarily in the central valley foothill, it thrives in grass lands and oak savannahs that have vernal pools and upland burrows of ground squirrels and pocket gophers. The poisoning of these rodents and destruction of their habitat leads to the demise of the salamander as well. With the introduction of agriculture and domestic grazing animals, vernal pools (long lasting seasonal pools) have all but been eradicated in California. This has forced the salamander to seek out stock ponds and occasionally slow-moving streams for breeding. Breeding pools must be fishless or the eggs will not survive.
The tiger salamander is rarely seen because it is fossorial and lives under ground in mammal burrows eleven months of the year. It comes out to breed with the first heavy winter rains, usually in December. It travels at night to breeding ponds, males arriving first and then females. A short courtship takes place and the male deposits a spermatophore on the bottom of the pond which the female picks up. Several hundred eggs are laid by the female but few will reach maturity. Eggs take 10-14 days to hatch into small larva which have gills. The larva will metamorphosis over the next three to seven months and rarely do they survive over winter. Metamorphous appears to be speed up in dryer years when ponds do not stay full. In especially dry/drought years breeding does not take place at all. Salamanders reach maturity in 3-4 years and females will start to breed at six years old. They live to approximately twelve years and females may only mate once or twice in their lifetime with less than eight eggs making it through metamorphosis.
Like most amphibians, Tiger salamanders feed on many invertebrates including, earthworms, insects, snails and occasionally will eat a small mammal.
Habitat destruction, poisoning of rodents, slow breeding rates, and predators like the introduced Bullfrog are all threatening this unique animal. Other predators include raccoons, garter snakes, foxes, coyotes, and bobcats.
Mount Diablo has a limited number of ponds in which these salamanders can breed and in the past few dry years little or no breeding has taken place obviously affecting future generations.