Empirical Tests of Biased Body Size Distributions in Aquatic Snake Captures

Abstract

Abstract Ecologists often rely on a suite of demographic parameters—such as age structure, body size distributions, population density, and sex ratios—to understand life history patterns, population dynamics, and community structure of snakes. Unfortunately, in many cases little consideration is given to how sampling techniques may influence the outcome of demographic studies. Herein, we use a combination of field capture techniques, an extensive database of field-captured snakes, and laboratory and field experiments to evaluate how capture methods may influence demographic assessments of several North American semi-aquatic snake species, including Agkistrodon piscivorus, Farancia abacura, Nerodia fasciata, N. floridana, N. rhombifer, N. taxispilota, Regina rigida, Seminatrix pygaea, and Thamnophis sauritus. We found that commercially available aquatic funnel traps (i.e., minnow traps) generally yielded biased assessments of population demography, but that the nature and magnitude of these biases varied p...