Demography of a Population of Ambystoma talpoideum (Caudata: Ambystomatidae) in Northwestern Louisiana

A population of Ambystoma talpoideum was monitored from 1977-1982 using mark-recapture techniques to document changes in population parameters. Body size differed significantly between the sexes; males had longer body lengths than females, females had greater masses than males, and males had longer cloacae than females. Sex ratios varied significantly from 1:1 during two of the 5 yr studied, and a shift toward more males was noted. Annual fecundity was 57-504 eggs/female based on oviducal and ovarian counts. Population natality was estimated to be 2555 eggs/year. Mature females were larger (snout-vent length) but oviposited fewer eggs than females from South Carolina. Clusters of 3-50 eggs were deposited within thin, clear jelly envelopes; single eggs were not found. Annual, biennial, and other reproductive cycles occurred, but most individuals (68%) were annual breeders. Growth rates declined logarithmically after hatching. Sexual maturity occurred at 2 yr of age, and the onset of reproductive senility occurred in the fifth year of age in females and in the seventh year of age in males. Breeding population size ranges, for three of the years studied, were 131-214 females and 177-220 males/year, and declines were indicated. Adult mortality rate was estimated to be 25.8% per breeding season, and longevity of more than 8 yr was documented.