BEE, M. A.; Carl von Ossietzky Universit�t, Oldenburg: A Test of the Dear Enemy Effect in the Strawberry Dart-poison Frog (Dendrobates pumilio)

Territorial animals commonly exhibit lower levels of aggression toward familiar neighbors in their usual territories than toward non-territorial “strangers”. This form of social recognition, termed the “dear enemy effect” or “neighbor recognition” is widespread among territorial songbirds, where it is mediated by a combination of vocal and spatial recognition cues. Despite the widespread occurrence of territorial social systems and the nearly ubiquitous use of acoustic communication in anuran amphibians, only two previous studies have demonstrated the vocal recognition of dear enemies in a frog. In this study, I conducted neighbor-stranger discrimination experiments in a third species of territorial frog, the strawberry dart-poison frog Dendrobates pumilio (Anuran, Dendrobatidae), to determine whether territorial males in this species behaviorally discriminated between the advertisement calls of neighbors and strangers. In the first field playback experiment, I broadcast a subject�s (N = 24) neighbor�s calls and the calls of an unfamiliar individual from the midpoint between the subject�s and the neighbor�s territories. Although males responded aggressively to the stimuli, they did not exhibit any differential responses to the calls of neighbors and strangers. In a second experiment, I broadcast the calls of a neighbor and a stranger to subjects (N = 22) through a speaker located in the approximate center of the neighbor�s territory. Males responded weakly to the playback, and no discrimination between the calls of neighbors and strangers was found. Thus, territorial males of the strawberry dart-poison frog appear not to behaviorally discriminate between the calls of neighbors and strangers. Several hypotheses for this lack of the dear enemy effect are considered.