Breeding sites, distribution and conservation status of the White-vented Storm-petrel Oceanites gracilis in the Atacama Desert

The White-vented Storm-petrel Oceanites gracitis is one of the world's least known seabirds and is listed as Data Deficient by the IUCN. To date, only one breeding colony, with less than ten pairs, is known from the Chungungo Islet in Chile. To understand the breeding habitat and the threats faced by the species, it is crucial to search for other colonies. We carried out field surveys of this species in the Atacama Desert between 2013 and 2020, searching for nests along c. 870 km of coastline, from sea level to 1700 m.a.s.l. We also revisited the breeding colony at the Chungungo Islet. To detect nests, we used endoscopic cameras and scent-trained dogs. We found two new breeding colonies in Pampa Hermosa and Pampa del Indio Muerto in the Atacama Desert, and additionally, we found two non-active breeding sites in Tocopilla and Sierra Miranda. Colonies were on different substrates, including crevices in saltpetre formations, gypsum and rocks (only Chungungo Islet). The threats identified for each breeding site include light pollution and habitat destruction by mining and energy projects. Further surveys are needed to estimate the population size and to assess the conservation status of this species.