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UK Seabird Monitoring Found Steep Declines While Great Black-backed Gull Trends Split Between Scotland and Wales

Adult lesser black-backed gull (Larus fuscus) on water
Conservation · Population & status

Official UK seabird monitoring published on 19 March 2026 reported steep long-term declines in natural-nesting lesser black-backed gulls (Larus fuscus), natural-nesting European herring gulls (Larus argentatus) and common terns (Sterna hirundo). Great black-backed gulls (Larus marinus) showed a more complex pattern, with a modest UK-wide decline that was too uncertain to distinguish clearly from no change but sharply contrasting trends in Scotland and Wales. The same release also reported lower common gull (Larus canus) productivity in 2024 than in 2023.

Three long-term declines were clear at UK level

The UK abundance index for natural-nesting lesser black-backed gulls was 72% below its 1986 baseline in 2024 and 81% below the 2000 level. For natural-nesting European herring gulls, the corresponding declines were 51% and 47%. The common tern index was 63% below 1986 and 60% below 2000. These are relative abundance indices from monitored breeding sites rather than complete national counts of every breeding bird. All six changes were statistically significant.

The gull indices for lesser black-backed and European herring gulls cover birds nesting in natural or semi-natural habitats rather than rooftop and other urban colonies. This distinction matters because urban colonies are much harder to monitor consistently and are not represented by these long-term natural-nesting trends.

Great black-backed gulls diverged sharply between Scotland and Wales

Across the UK, the great black-backed gull abundance index was 16% below the 1986 baseline and 20% below the 2000 level, but these changes were too uncertain to distinguish clearly from no change. Its estimated breeding productivity nevertheless increased from 2023 to 2024.

The country-level abundance trends were much more divergent. In Scotland, the index was 59% below 1986 and 57% below 2000, with both declines clearly supported. In Wales, by contrast, the abundance index was 170% above the 1986 baseline, a clear long-term increase. The shorter-term increase from 2000 to 2024 was too uncertain to distinguish clearly from no change.

Productivity moved in different directions in 2024

The annual productivity estimates did not all move in the same direction. Common gull, lesser black-backed gull and common tern productivity was lower in 2024 than in 2023, while European herring gull and great black-backed gull productivity increased. The year-to-year productivity differences are annual estimates rather than established long-term trends and should be read separately from the abundance changes above.

Sources and image credit

  1. Joint Nature Conservation Committee. (2026, March 19). Official statistic on seabird breeding population changes.Primary official statistic reporting UK and country-level breeding abundance changes from 1986 to 2024 and productivity estimates for 2023–2024.
  2. Harris, S. J., Baker, H., Balmer, D. E., Bolton, M., Burton, N. H. K., Clarke, J. A. E., Dunn, T. E., Evans, T. J., Hereward, H. F. R., Humphreys, E. M., Langlois Lopez, S., Money, S., Taylor, E. A., & O'Hanlon, N. J. (2026). Seabird population trends and causes of change: 1986–2024. British Trust for Ornithology.Primary annual Seabird Monitoring Programme report supporting the official statistic and providing species-specific abundance and productivity results.

Image: Susan Marley — lesser black-backed gull (Larus fuscus); iNaturalist / Wikimedia Commons. Representative image for this story; not presented as an animal or scene from the reported study or event. · CC BY 4.0 · Source

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Population & status

SPECIES IN THIS STORY

Species in this story

Common Gull Larus canus Explore species Lesser Black-backed Gull Larus fuscus Explore species Common Tern Sterna hirundo Explore species European Herring Gull Larus argentatus Explore species Great Black-backed Gull Larus marinus Explore species

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