Five seabird species are added to the Birds of Conservation Concern Red List in this addendum to the 2021 update, bringing the total number of Red-listed seabird species to 10, up from six since seabirds were last assessed. The Amber List of seabirds moves from 19 to 14 species, and the Green List increases from one to two species.

The report includes detailed information about the population trends and breeding success of seabirds in Northern Ireland, over the 2023 breeding season. Notably, Fulmar and Kittiwake populations are reported to be experiencing continued declines, while Guillemot, Common Gull and Herring Gull populations show increases at most breeding sites. Low productivity was reported in Black-headed Gulls, Sandwich Terns and Common Terns, likely due to the impacts of highly pathogenic avian influenza (HPAI). Although Black-headed Gulls make up the majority of confirmed HPAI mortality cases in Northern Ireland in 2023, other birds significantly affected include terns, Kittiwakes and auks. A contributor report about HPAI in Northern Ireland by Ronan Owens (Higher Scientific Officer, DAERA, NIEA) details developments in environmental organisations’ responses to HPAI in 2023, including cross-sector communication, improved surveillance and monitoring of HPAI impacts, and improved online systems for the public to report dead birds. Monitoring reports for Strangford Lough and the Outer Ards are included, as well as several additional contributor articles: Copeland gull censuses, by Roisin Kearney (Assistant Conservation Officer, RSPB). The Copeland Islands host one of the largest mixed gull colonies in Northern Ireland, with significant numbers of Lesser Black-backed Gulls and Herring Gulls. The annual gull census was established in 2018; the article details the refinement of the methodology to date as well as the census results so far. Manx Shearwater tracking, by Patrick Lewin (DPhil Student, OxNav, Dept. of Biology, University of Oxford). Tracking the Manx Shearwaters that breed on Lighthouse Island (one of the three Copeland Islands) began in 2007. The article describes the history of tracking Manx Shearwaters from Copeland, including recent advances in technology that have allowed the tracking of fledgling birds as well as adults of breeding age, and the impact of this research on the conservation of shearwaters. Puffin surveys on Rathlin, by Ric Else (Life RAFT Senior Research Assistant, RSPB). Rathlin Island hosts Northern Ireland’s largest seabird colony. The response of seabirds to the removal of introduced Ferrets and Brown Rats from Rathlin is currently being monitored, with a particular focus on Puffins. These birds are especially vulnerable to mammalian predators because of their burrow nests. The article describes the challenges associated with calculating a population estimate, monitoring productivity and mapping the distribution of this species, and how these are being addressed in seabird surveys on Rathlin.