The ability to recognize and categorize other conspecifics is a key component of practically all animal social behaviors. We are studying the mechanisms and evolution of a form of social recognition common among territorial animals, which often direct lower levels of aggression toward their established "neighbors," but respond very aggressively toward unfamiliar "strangers." In such systems, neighbors are said to be "dear enemies." In many taxa, the establishment of dear-enemy relationships depends on the ability to learn about the individually distinctive properties of a neighbor's acoustic signals. The goal of this research is to discover mechanisms for vocally mediated social recognition in frogs and the underlying ecological and social factors that favor its evolution. Frogs exhibit a remarkable diversity of mating systems - even within a single genus - that ranges from scramble competition (and hence no territoriality) to resource defense polygyny, in which males occupy long-term territories that contain key resources for reproduction.

We have conducted extensive analyses to determine the patterns and sources of individuality in frog vocalizations (Bee et al. 2001, Bee & Gerhardt 2001a, Bee 2004, Bee et al. 2010, Pettitt et al. 2013, Tumulty et al. in press). Fundamental frequency and related spectral properties often exhibit the lowest within-individual variation, the highest ratio of among-individual to within-individual variation, and the highest repeatability between recordings made on different days. In multivariate discriminant function analysis, calls are assigned to the correct individual more often than expected by chance, and fundamental frequency is often significantly correlated with discriminant functions that explain considerable variation among individuals. The reason that fundamental frequency varies so little within individuals is because this call property is determined largely by body size. Hence, the size-related variation in fundamental frequency among males in the population can function as a potential voice recognition cue in many species. Our earlier wok using field playback experiments based on the habituation-discrimination paradigm has shown this to be the case in North American bullfrogs (Bee & Gerhardt 2001b, Bee & Gerhardt 2001c, Bee & Gerhardt 2002).

To better understand the evolution of voice recognition, we are engaged in a long-term effort to conduct comparative studies of neighbor-stranger discrimination in territorial frogs. The ultimate goal of this work is to identify the ecological and social selection pressures that favor the evolution and expression of this behavior within a phylogenetic context. So far, we have conducted studies of the strawberry poison frog (Oophaga pumilio) in Panama (Bee 2003), the golden rocket frog (Anomaloglossus beebei) and the Kaie rock frog (Anomaloglossus kaiei) from Guyana (Tumulty & Bee in preparation), the brilliant-thighed poison frog (Allobates femoralis) in French Guiana (Tumulty et al. in press), and the olive frog (Babina adenopleura) in Taiwan (Chuang et al. 2017).

You can read about this work in the following reviews:

Bee MA (2016) Social recognition in anurans. In: Psychological Mechanisms in Animal Communication (eds. Bee MA and Miller CT), pp. 169-221. New York: Springer.

Bee MA, Reichert MS, Tumulty J (2016) Assessment and recognition of rivals in anuran contests. Advances in the Study of Behavior, 48, 161-249.