Differential Responses of Eastern Red-backed Salamanders (Plethodon cinereus) to Conspecifics and Centipedes

Abstract

Plethodontid salamanders are known to aggressively interact not only with conspecifics but also with other potential competitors, such as centipedes. Eastern Red-backed Salamanders (Plethodon cinereus) are thus expected to respond aggressively toward potential competitors, both conspecifics and heterospecifics. Additionally, the residency status of a salamander can influence aggression levels. Male P. cinereus were exposed to one of four substrate chemical cue treatments: control, self, conspecific, or centipede (Scolopocryptops sexspinosus) to determine their behavioral reaction to the presence or absence of cues from conspecifics and heterospecifics. Salamanders were additionally paired with a conspecific or a centipede in different “habitats” to determine if behavioral interactions were affected by residency status. Salamanders did not respond aggressively when exposed to chemical cues from conspecifics or heterospecifics. However, P. cinereus increased the time spent in aggressive postures when physically paired with a centipede, but showed no increase in aggression when paired with a conspecific. Plethodon cinereus in our population did not respond aggressively toward conspecifics in either experimental setting; however, they did respond to centipedes with increased aggression regardless of their residency status, indicating that the decrease in aggression towards conspecifics is not paralleled by a decrease in aggression towards heterospecifics.