ANNUAL VARIATION IN POPULATION ESTIMATORS FOR A SOUTHERN POPULATION OF AMBYSTOMA MACULATUM

Abstract

For six breeding seasons (1997–2002), we conducted an intensive mark-recapture study on a breeding population of the spotted salamander, Ambystoma maculatum, near the southern edge of their range in east-central Alabama. A drift fence completely encircling an ephemeral pond was used to capture all adult salamanders migrating into or out of the pond, and passive integrated transponders were used to provide individual identification. The Jolly-Seber method of population estimation was used to estimate three population parameters (size, gains, and survivorship); population growth rate was also estimated. Gains varied annually, ranging from 24 ± 16 to 101 ± 24, and population growth rate was low (r = 0.18 ± 0.188), suggesting inconsistent recruitment. Consistent with life history parameters of long-lived, late-maturing species, survivorship (range 0.629 ± 0.064 to 0.699 ± 0.08) and breeding population sizes (range 189 ± 24 to 260 ± 16) remained essentially constant. The demographics for A. maculatum provided by this study are useful for planning conservation initiatives.