Habitat Use by Paedomorphic Salamanders

Many salamander species exhibit a biphasic life history strategy, in which a larval stage develops in an aquatic environment until metamorphosis, and then transitions to a terrestrial metamorphic stage. In some species, an additional life history strategy called paedomorphosis exists, in which a portion of the population reaches sexual maturity without undergoing metamorphosis. Paedomorphs commonly grow to a large size, and can be an important predator in aquatic environments. Larval and paedomorphic salamanders are highly cannibalistic, with larger salamanders commonly consuming smaller individuals up to a third of their own body size. It is not known if different size classes of paedomorphic salamanders use aquatic habitat differently, but it is possible that smaller individuals may seek to avoid larger individuals by using sub-optimal habitat. In late winter and early spring, metamorphic mole salamanders (Ambystoma talpoideum) return to ponds to breed. Paedomorphic individuals will readily mate with both adult morphs, and in the breeding season may move to shallower sites in order to maximize their chances of encountering mates. Under these conditions, smaller individuals seeking to avoid predation may move to deeper water. Using data collected in 1994-96 from two arrays of minnow traps of varying depths in the United States Department of Energy’s Savannah River Site in Aiken County, I investigated whether paedomorphic mole salamander population size structure varies by depth. I used ANOVA and Levene’s tests to determine if the mean and variance of salamander size varies with depth. The results show little evidence to support the above hypotheses.