Survival, breeding frequency, and migratory orientation in the Jefferson Salamander, Ambystoma Jeffersonianum

Abstract

Accurate estimates of demographic parameters, such as survival and breeding frequency, are necessary for the conservation and management of animal populations. Additionally, life-history data are required for gaining an empirical understanding of the ecology of natural populations. We monitored a population of Jefferson Salamanders (Ambystoma jeffersonianum) breeding in a permanent mountain-top pond at the southern limit of this species' geographic range in Virginia over four years. We used closed multistate mark-recapture models with Pollock's robust design to estimate the demographic parameters of this population. Additionally, we used point-of-capture data to compare the orientation of migrations into and out of the pond within and among years. Our model selection results support consistent annual adult survival across years with higher estimates for males compared to females. Our estimates of the probability of breeding in sequential years were high for both sexes during the four years of our study. Our model rankings and capture probability estimates indicate that females had a higher probability of detection when entering the breeding pond, likely reflecting differences between the sexes in arrival time to the pond. We found directionality in some, but not all, annual migrations, despite indications of individual fidelity in orientation across years. Our study provides the first estimates of breeding probability and assessment of migratory orientation patterns for A. jeffersonianum and contributes to the understanding of the reproductive ecology and natural history of pond-breeding amphibians. © 2011. Stephen De Lisle. All Rights Reserved.