KINSHIP AND ASSOCIATION IN COMMUNALLY ROOSTING BLACK VULTURES

Black vultures, Coragyps atratus, spend each night in a communal roost , and individuals sleep at several different roosts over time. They fe ed in large aggregations at carcasses and engage in apparently coopera tive behaviour within coalitions of individuals that co-occur predicta bly at both roosts and carcasses. Roost census data and DNA fingerprin ting results were used to investigate whether black vultures tend to r oost in the company of genetic relatives. Restricting the analysis to dyads of breeding adults that were the heads of known lineages and wer e not mated to one another, a positive correlation emerged between ind ices of the genetic similarity of individuals and their tendency to us e the same roost on the same night. The results provide evidence of lo ng-term associations between some closely related breeding adults, ass ociations that appear not to be simply a consequence of natal philopat ry but reflect the daily reassembly of coalitions at communal roosting sites. This social organization could facilitate the evolutionary sta bility of cooperation among communally roosting black vultures.