Territoriality in a Terrestrial Salamander: the Influence of Resource Quality and Body Size

Abstract

AbstractIntraspecific interference competition associated with territoriality has been documented in laboratory studies of the red-backed salamander, Plethodon cinereus. I used laboratory and field experiments to study the effect of resource quality and body size on such competition. In an experiment in southwestern Virginia, cover objects (e.g., logs) from which the resident salamanders were removed were invaded significantly more often than cover objects from which the resident salamander was not removed. These data provide the first direct test of territoriality for a salamander in a natural habitat. Newly invading salamanders were significantly smaller than the original territorial residents. Therefore, large body size is an advantage in territorial encounters. Because cover objects are important resources for terrestrial salamanders, characteristics of the cover object may contribute to territory quality. In an experiment conducted during warm summer weather at the Virginia site, soil temperatures under large cover objects were significantly cooler than those under small cover objects or under the leaf litter. Large cover objects may therefore benefit the salamanders by providing a buffer zone between the salamander and extreme environmental temperatures on the forest floor. In both laboratory and field experiments, when salamanders were offered a choice between large and small cover objects, both large and small salamanders exhibited a significant preference for large cover objects. Also I censused cover objects in a natural mixed hardwood forest habitat during courting and noncourting seasons and, for both seasons, I found a significant positive correlation between the body size of the salamander and the size of the cover object that it occupied. I conclude that, in this natural forest habitat, there is intraspecific competition for high quality cover objects and larger individuals are more successful competitors than smaller individuals.