Habitat Selection and Interspecific Competition in Two Species of Plethodontid Salamanders

A series of field enclosure and laboratory experiments was conducted to test the hypothesis that intespecific interference competition plays no role in the microhabitat utilization and activity patterns of the plethodontid salamanders Desmognathus fuscus and Desmognathus monticola. Single—species and mixed—species groups were tested to determine if the presence or absence of potential competitors influence either species' selection of substrate texture, selection of substrate moisture, utilization of cover object sizes, proximity to the stream bed, magnitude of activity and temporal activity patterns. In single—species groups significant differences were found between species in all of the variables tested except temporal activity pattern. Relative species differences in micro—habitat utilizations shown experimentally during this study reflect closely those commonly observed in the field for the two species. The preferences of each species for substrate texture, substrate moisture, and cover object sizes were independent of the presence or absence of potential competitors; temporal activity patterns were also independent of the composition of test groups. Evidence for interspecific interference was found, however, in the proximity of individuals to a stream bed, and in magnitude of activity. D. fuscus utilized microhabitats farther than from the stream bed and was significantly less active in the presence of D. monticola than when the latter species was absent. These two species of Desmognathus possess distinctly different patterns of hbatiat utilization and activity which could account for the field distributions observed; yet evidence for interspecific interference points to competition as another factor in their spatial distributions.