Spread the word: male manakins advertise the presence of display sites with neighbouring competitors

Abstract

Reproductive behaviour is generally under strong natural and sexual selection, meaning that variation in mate attraction investment reveals important fitness trade-offs. Nevertheless, in many taxa with sex-specific displays, individuals differ considerably in such investment. Male white-ruffed manakins, Corapipo altera (Pipridae), exhibit dramatic variation in display investment, despite having a mating system shaped by strong sexual selection. We tested three alternative hypotheses that could explain this variation: (1) individual quality and condition, (2) competition or (3) cooperation. We manipulated the social environment of male manakins at display sites in two experiments. First, we increased the acoustic signalling around focal males’ display sites by broadcasting the sounds of other displaying males to simulate elevated display of neighbouring males. Second, we temporarily prevented neighbouring males from using their display sites, thereby increasing the competition at focal display sites. Males reduced rates of vocalization in response to elevated acoustic signalling, suggesting that males may cooperate with neighbours to advertise the locations of leks, minimizing their individual effort when possible. The number of individuals at the focal display site and the number of silent displays increased when neighbours were prevented from displaying nearby, consistent with the competition hypothesis. However, the constancy in time investment and rates of other display behaviours throughout both manipulations suggests that male quality or condition underlies much of the individual variation in behaviour at display sites. Overall, our results are consistent with cooperation and individual quality mediating individual investment in display site advertisement. While manipulations created opportunities for competition, the responses of focal males were not consistent with antagonist social interactions affecting investment in display. This work demonstrates the importance of both intrinsic and social drivers shaping investment in courtship behaviour and highlights the potential for multimodal displays to facilitate cooperation. • Mating display effort may reflect individual quality, competition or cooperation. • An experimentally increased acoustic signal reduced male manakin vocalizations. • Preventing neighbours from displaying increased male physical displays. • Results are consistent with cooperation and individual quality shaping investment. • Multimodal signalling may facilitate cooperative aspects in competitive interactions.