The status of the UK's breeding seabirds: an addendum to the fifth Birds of Conservation Concern in the United Kingdom, Channel Islands and Isle of Man and second IUCN Red List assessment of extinction risk for Great Britain.

Abstract

This paper provides updated status assessments for 28 species of current or former breeding seabird in the United Kingdom by way of a two-stage addendum to Birds of Conservation Concern 5: firstly, a pre-H5N1 Highly Pathogenic Avian Influenza (HPAI) baseline and, secondly, an examination of apparent HPAI impacts to date. Two species were classed as former breeders. Of the currently occurring species, ten (38%) were placed on the Red list, 14 (54%) on the Amber list and two (8%) on the Green list. The full UK BoCC list now contains 73 species (30%) on the Red list, 99 (40%) on the Amber list and 73 (30%) on the Green list. The overall status of seabirds has deteriorated since the last comprehensive UK BoCC assessment in 2015. Leach’s Storm-petrel Hydrobates leucorhous, Common Gull Larus canus, Great Black-backed Gull Larus marinus and Arctic Tern Sterna paradisaea have been added to the Red list owing to pre-HPAI population declines. Great Skua Stercorarius skua has joined the Red list owing to severe HPAI impacts. On a more positive note, European Shag Gulosus aristotelis and Black Guillemot Cepphus grylle have moved from the Red to Amber and Amber to Green lists, respectively. A two-stage addendum to the second International Union for Conservation of Nature (IUCN) Red List review of extinction risk for breeding seabird species in Great Britain is also presented in this paper. This, too, shows an overall decrease in the status of seabirds since 2017, with 18 (69%) of 26 regularly occurring breeding seabird species assessed as being threatened with extinction from Great Britain. Updating the full species list reveals that 115 (49%) of 235 regularly occurring species are assessed as threatened with extinction from Great Britain. The UK remains internationally important for breeding seabirds but many populations are under severe pressure, raising concerns around their resilience. There remains uncertainty regarding the scale of the population-level effects of HPAI on some species. All species will be assessed again in BoCC6 and GB IUCN3, currently scheduled for publication in 2027.