The composition, stability, and kinship of reproductive coalitions in a lekking bird

Male vertebrates often form reproductive coalitions to gain access to or defend females. One striking example occurs in the wire-tailed manakin (Pipra filicauda; Aves: Pipridae), where pairs of males form coalitions to display for females on leks. Here, we use data from a long-term study of the wire-tailed manakin to quantify the composition and stability of display coalitions, to examine how coalitions influence behavioral variation, and to determine if males gain indirect genetic benefits from coalition membership. Our data show that coalitions were most often formed between males of different status and that the presence of coalition partners increased a male's display rate via social facilitation. Display coalitions were nonrandom and varied in stability with male age. Moreover, our data suggest that both floaters and territorial males maintain multiple coalition partnerships through time. Maintenance of fixed partnerships for territorial males is hypothesized to have reproductive fitness benefits by increasing display synchronization and signal intensity. Finally, our data show that although males do not appear to gain indirect inclusive fitness benefits by joining display coalitions with relatives, the kin structuring observed within male social networks is likely a consequence of strong reproductive skew, short dispersal distances, and limited recruitment opportunities. Copyright 2011, Oxford University Press.