RULES OF ENGAGEMENT FOR ADULT SALAMANDERS IN TERRITORIAL CONFLICTS WITH HETEROSPECIFIC JUVENILES

Coexisting species within a guild have the potential for resource over lap and consequently for interspecific competition (e.g., interspecifi c territoriality). When the adults are of different sizes, which frequ ently is the case in terrestrial salamander communities in eastern Nor th America, competition may occur between juveniles of the larger spec ies and adults of the smaller species. Adults of the relatively small red-backed salamander (Plethodon cinereus: up to 13 cm total length) d efend intra- and intersexual territories on the forest floor, and they are broadly sympatric with the larger P. glutinosus (up to 21 cm tota l length). Although individuals of the two species share the same fore st floor habitat, we found significantly fewer juveniles of P. glutino sus sharing territories with 336 same-size adults of P. cinereus than would be expected by random chance alone. In laboratory experiments, r esidential adults of P. cinereus were as aggressive toward juvenile in truders of P. glutinosus as they were toward adult conspecific intrude rs. Therefore, adults of P. cinereus appear to defend territories agai nst juveniles of P. glutinosus, illustrating how interference competit ion may depend on the symmetry of sizes between the species.