Size-Dependent Responses of Resident Male Red-Backed Salamanders to Chemical Stimuli from Conspecifics

Territorial residents are predicted to respond to the presence of scent marks from conspecifics by vigorously re-marking the area that contains the intruder's scent mark or by performing agonistic displays. This study examined the response of resident, male red-backed salamanders (Plethodon cinereus) to swabs marked with chemical stimuli from conspecific males. Residents exhibited significantly greater exploratory behavior to conspecific-marked swabs than to control swabs and exhibited significantly more nose-tapping behavior (i.e., chemosensory sampling) in the control condition. The presence of pheromones from conspecifics did not affect marking behavior by residents. Residents did not exhibit consistent changes in agonistic behavior in response to pheromones from conspecifics. Instead, agonistic behavior was significantly associated with the body size of the resident, with larger individuals tending to become more aggressive and smaller individuals tending to become more submissive. Our study is the first to document an apparent effect of absolute body size (i.e., as opposed to relative body size) on agonistic behavior of salamanders.