The Neoichnology of Two Terrestrial Ambystomatid Salamanders: Quantifying Amphibian Burrows Using Modern Analogs

Abstract

This experiment involved the study of two species of ambystomatid salamanders, Ambystoma tigrinum and Ambystoma opacum (Amphibia: Caudata). Individual salamanders were placed in sediment-filled terrariums and allowed to burrow for 7 to 14 days under natural environmental conditions. Salamanders were then removed and their burrows cast, excavated, and described both qualitatively and quantitatively. Quantitative measurements included the number of surface openings, width, height, width-to-height ratio, total length, maximum depth, slope, branching angle, complexity, and tortuosity. Additional experiments involved variations in soil composition and soil moisture. A. tigrinum burrowed through excavation and compaction techniques whereas A. opacum only used compaction. Burrows produced by A. tigrinum consisted of ramps, branched ramps, U-, W-, Y-, and J-shaped burrows. Small-scale surface mounds were also created by Ambystoma tigrinum. Burrows produced by A. opacum consisted of ramps and branched ramps. Sinuous to straight surface trails were also produced by A. opacum. There was no recognized change in behavior or burrow properties in response to changes in the environmental parameters.