Searching for a breeding population of Swinhoe’s Storm-petrel at Selvagem Grande, NE Atlantic, with a molecular characterization of occurring birds and relationships within the Hydrobatinae

Long-distance dispersal plays a critical role in population dynamics, particularly in species that occupy fragmented habitats, but it is seldom detected and investigated. The pelagic seabird Swinhoe’s Storm-petrel, Oceanodroma monorhis , breeds exclusively in the NW Pacific. Individuals have been regularly observed in the Atlantic Ocean since the 1980s, but breeding has never been confirmed. In this study, we searched for evidence of breeding of Swinhoe’s Storm-petrels on Selvagem Grande Island, NE Atlantic, between 2007 and 2013. During this period, six individuals were captured, sexed and characterized molecularly for two mitochondrial loci, cytochrome oxydase I and the control region, to confirm species identity, survey genetic diversity and estimate evolutionary relationships within the Hydrobatinae. These individuals were confirmed to be Swinhoe’s Storm-petrels, and all except one are females. Phylogenetic analyses suggest sister relationship with Matsudaira’s Storm-petrel and dismiss misidentifications with other dark rump species. Patterns of genetic variation suggest that dispersal occurred likely by more than a single female. Despite the record of a pair duetting in a burrow, breeding could not be confirmed. Swinhoe’s Storm-petrels are regularly occurring at Selvagem Grande, but capture/recapture patterns suggest that a possible breeding population is small and likely not self-sustaining. In seabirds, long-distance dispersal events may facilitate colonization of new habitats created in the context of predicted climate change impacts on the marine ecosystems.