TERRITORIAL SALAMANDERS ASSESS SEXUAL AND COMPETITIVE INFORMATION USING CHEMICAL SIGNALS

Adult male and female red-backed salamanders, Plethodon cinereus, gain information about gender and body size of conspecifics through chemical signals. Responses to information about gender differed between the sexes: females produced faecal pellets (territorial pheromonal markers) fastest when exposed to their own pheromones while males produced faecal pellets fastest when exposed to pheromones of females. These data suggest that for females the primary pheromonal function of faecal pellets is advertisement (i.e. defence) of their own areas, and that faecal pellets produced by males are of primary importance in the attraction of mates. Two types of responses to information concerning body size were found. (1) Both male and female intruders exposed to the pheromones of resident males tended to produce larger faecal pellets when the intruder and resident were of similar body sizes. This phenomenon was not observed when the resident was female. (2) Male intruders were significantly more aggressive when exposed to the pheromones of individuals of similar body size and more submissive when exposed to pheromones of individuals that were larger. Therefore, information about body size (an indicator of competitive ability) of males may be transmitted via chemical signals and may cause changes in the behaviour of conspecifics. © 1990 The Association for the Study of Animal Behaviour.