Discrimination of infant isolation calls by female greater spear-nosed bats, Phyllostomus hastatus

In colonial species, recognition of offspring should be under strong selection. For accurate identification to occur, offspring must produce individually distinctive signals and parents must be able to discriminate between signals. Female greater spear-nosed bats roost in stable social groups and use infant vocalizations, termed isolation calls, to locate and identify their young. In this study, we investigated both the production and perception of isolation calls in P. hastatus. First, we measured acoustic features of calls and found that, after controlling for ontogenetic effects, sufficient variation exists between pups for isolation calls to function as individual signatures. Moreover, calls of pups from the same social group were more similar in spectral and spectrotemporal features than were calls of pups from different social groups, indicating that these features are probably heritable. We used psychoacoustic experiments in the laboratory to determine whether adult females could discriminate between calls from pups in the same or different social group. Females discriminated between pups when faced with a template-matching task and their performance was correlated with the salience of spectral and spectrotemporal features. We found no difference in performance when females had to discriminate between pups from the same and different social groups. These results indicate that females should be able to accurately identify their young using isolation calls.