Seabirds of São Paulo, Brazil: species occurrence, conservation status and knowledge gaps

Abstract

Seabirds across all the seas and oceans of the planet interact with human activities and, as a result, approximately 30% of all species are in decline and threatened with extinction. The knowledge of the composition of seabird communities in both breeding and non-breeding ranges is necessary to guide appropriate conservation measures according to its status. Fisheries, oil and natural gas exploration, offshore wind farms, among other activities, require regulation and legal frameworks to protect seabirds and other organisms in this environment. The state of São Paulo already hosts numerous such activities within its territorial waters and has its own environmental protection legislation (including a list of threatened fauna species), requiring impacts on threatened species are evaluated. The present study compiles all available information on seabirds in São Paulo and update its species list based on data obtained from literature reviews, museum specimens, band recovery records, and citizen-science platforms. São Paulo has a total of 68 recorded seabird species, including the recently recognized Oceanites chilensis and the sole Brazilian records of Pterodroma externa and Pachyptila turtur. Most (50 species) are migratory, with 14 species from the Northern Hemisphere and 36 from the Southern Hemisphere. Only 18 species are resident in Brazil, of which six breed along the São Paulo coast. Among the recorded species, 24 (35%) are listed as threatened with extinction by the IUCN, MMA and/or SMA lists. Notably, three (50%) of the six resident breeding species in São Paulo are threatened. Most of the new records came from beached birds, particularly through the Beach Monitoring Program (PMP). Unfortunately, this program forwards few of the collected specimens, including rare and unprecedented records for São Paulo’s avifauna, to scientific collections. Based on the available studies on São Paulo’s seabirds, even basic data on breeding biology, home range, and diet of even the commonest coastal, and resident species is virtually nonexistent. Similarly, knowledge regarding trends in population and occupancy of breeding sites is scarce, with only outdated data available from studies carried between 1997 and 2005. Further studies and monitoring programs on the breeding areas of these resident species are necessary to fill these knowledge gaps and provide updated scientific information to support effective conservation measures.