Helpers at a Sapayoa nest are kin

The natural history of the Sapayoa Sapayoa aenigma, the sole member of the Sapayoidae and the only New World representative of the 'Old World suboscines', is poorly known. Previously, we reported a pair of adult Sapayoas breeding with assistance from two immature males, but their kinship was unknown. Here, we use double-digest restriction site-associated DNA sequencing (ddRAD-seq) to conduct parentage and relatedness analyses among this group. We found that the members of the adult pair were unrelated, but all other dyads were probably first order (parent-offspring or full sibling). In addition, the helper males were very unlikely to have sired either of the chicks. We conclude that the group consisted of two unrelated adults and two offspring from a previous brood. These results provide important context for social behaviours observed within the group, which included mounting events; such behaviour may be involved in group cohesion.