Food-associated calls in disc-winged bats

Abstract

Animals that engage in social foraging can produce food-associated calls that elicit two main responses in receivers: the recruitment of other individuals to a foraging site, and an increase in feeding-related behaviors in conspecifics. Spix's disc-winged bat, Thyroptera tricolor, is a highly gregarious species that lives in stable social groups and relies on group call-and-response vocalizations to find ephemeral roosting sites. Because this bat also is known to feed on resources that are abundant but ephemeral - for example insect swarms - we hypothesized that it likewise emits vocalizations that serve to recruit conspecifics to a foraging site and elicit food consumption. We found that indeed, feeding bats emitted distinct vocalizations exclusively while consuming an abundant prey item, a call type that has not been previously described in the acoustic repertoire of any bat to date. We also observed that these "food calls" prompted responses typically associated with food-calling: they increased both feeding-related behaviors and social recruitment. Specifically, we observed that the onset of the consumption of novel prey items was strongly associated with the emission of food calls but not with other types of sounds. In addition, individuals approached a speaker broadcasting food calls, especially when food calls had not been broadcast before, while other types of sounds did not consistently prompt inspection. Taken together, these results suggest that T. tricolor coordinates foraging behavior through the emission of food-associated communication calls.