The Great Black-backed Gull Larus marinus is a generalist species that inhabits temperate and arctic coasts of the north Atlantic Ocean. In recent years, there has been growing concern about population declines at local and regional scales; however, there has been no attempt to robustly assess Great Black-backed Gull population trends across its global range. We obtained the most recent population counts across the species’ range and analysed population trends at a global, continental, and national scale over the most recent three-generation period (1985–2021) following IUCN Red List criteria. We found that, globally, the species has declined by 43%–48% over this period (1.2–1.3% per annum, respectively), from an estimated 291,000 breeding pairs to 152,000–165,000 breeding pairs under two different scenarios. North American populations declined more steeply than European ones (68% and 28%, respectively). We recommend that Great Black-backed Gull should be uplisted from ‘Least Concern’ to ‘Vulnerable’ on the IUCN Red List of Threatened Species under criterion A2 (an estimated reduction in population size >30% over three generations).

大黑背鸥Larus marinus是一种多面性物种，栖息于北大西洋的温带和北极海岸。近年来，人们越来越担心地方和区域范围内的人口下降；然而，目前还没有尝试对全球范围内的大黑背鸥种群趋势进行强有力的评估。我们获得了该物种范围内的最新种群数量，并按照 IUCN 红色名录标准分析了最近三代时期（1985 年至 2021 年）全球、大陆和国家范围内的种群趋势。我们发现，在全球范围内，该物种在此期间下降了 43%–48%（每年分别为 1.2–1.3%），在两种不同情景下从估计的 291,000 个繁殖对减少到 152,000–165,000 个繁殖对。北美人口下降幅度比欧洲人口下降幅度更大（分别为 68% 和 28%）。我们建议，根据标准 A2，大黑背鸥应在 IUCN 受威胁物种红色名录中从“最不受关注”升级为“易危”（估计在三代内种群数量减少 > 30%）。