Endemic koloa maoli (Hawaiian Duck, <i>Anas wyvilliana</i> ) shows preferential social associations, but not based on plumage or genetic relatedness

The koloa maoli (Hawaiian duck, or koloa) is a federally-endangered, island endemic bird. Like other Hawaiian waterbirds, koloa are threatened by introduced predators and habitat loss, but also specifically by hybridization with feral mallards and localized avian botulism outbreaks. Currently, the island of Kaua'i has the largest population of non-admixed koloa. We used capture-mark-recapture and genetic data of koloa at two wetland sites on Kaua'i to examine their sociality and spatial genetic structure.Koloa formed preferential social associations, but they were not based on plumage traits, body mass or genetic relatedness.There was no spatial genetic structure for males and females within a wetland site. Our results suggested that 1) koloa have no preference for mallard-like plumage that might increase hybrid pairing, 2) localized (within-refuge) botulism outbreaks are unlikely to remove close relatives and unique genetic lineages, and 3) translocation of groups could maintain social associations without limiting genetic diversity.