Life history and demographic variation in the California Tiger Salamander (Ambystoma californiense)

In December 1991, we initiated a long-term study of the California Tiger Sa lamander (Ambystoma californiense) at a breeding pond in Monterey County, C alifornia. Because of habitat loss, this species is a candidate for federal endangered species status, but many basic features of its life history and demography have not been studied in detail. During the first seven years o f this study, we captured, measured, individually marked, and released 657 breeding adults and 1895 newly metamorphosed juveniles at the drift fence e ncircling this pond. We also used skeletochronology to investigate age stru cture in cohorts of breeding adults. Numbers of breeding adults varied by m ore than a factor of four among years, and annual juvenile production range d from 121-775 metamorphs, Contrary to the results of related studies, tota l juvenile production was positively related to the total biomass of breedi ng females. Both skeletochronology and mark-recapture data indicate that mo st individuals do not reach sexual maturity until 4-5 years of age, and, al though individual longevity can exceed 10 years, less than 50% of individua ls returned to breed a second time. These results suggest that this breedin g population was a reproductive sink during the period of this study and th at isolated breeding ponds may be insufficient for the long-term maintenanc e of viable populations of A. californiense.