Males of a suboscine lekking bird exhibit neighbor-stranger discrimination

Abstract

The ability to discriminate the vocalizations of neighbors from strangers is one way individuals can reduce conflict and minimize the associated physical and energetic costs. Although individual vocal variation and neighbor-stranger discrimination has been tested across various taxa, within birds, it is more commonly investigated in oscine passerines and territorial species, while suboscine passerines and lekking species are often neglected. Red-capped manakins, Ceratopipra mentalis, are a suboscine lekking bird that is known to exhibit individual variation in their whistle-peep vocalizations. We performed a playback experiment at C. mentalis leks to evaluate whether they exhibit neighbor-stranger discrimination at the lek-scale. We found that C. mentalis males responded more quickly to strangers compared to neighbors, suggesting that strangers are a greater threat to males than neighboring individuals. Neighbor-stranger discrimination was only observed in vocal responses, not movement responses, and differences in total vocal responses were only observed when we evaluated the changes in response to neighbors versus strangers over time. These findings add to a growing body of literature demonstrating that non-territorial and suboscine species are capable of neighbor-stranger discrimination. Further examination of neighbor-stranger discrimination in these understudied species can yield insights into the functions of vocalizations, and in particular male-male interactions and mate choice in highly sexually-selected species.