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Scotland’s European Herring Gull Index Was 54% Below Its 1986 Baseline

Adult European herring gull on a nest in Dornoch, Scotland
Conservation · Population & status

Breeding abundance of European herring gulls (Larus argentatus) in Scotland was estimated to be 54% lower in 2024 than at the 1986 baseline in NatureScot’s latest Scottish Seabird Indicator. The long-term decline was statistically significant.

The index is relative to a 1986 baseline of 100

The indicator is based on annual monitoring from a representative sample of seabird colonies in the UK Seabird Monitoring Programme. The abundance index uses 1986 as a baseline of 100, so a value 54% lower corresponds to an index of about 46 rather than a direct count of birds lost. For European herring gull, NatureScot used data from 75 colonies and lists breeding numbers of 37,349 for 2024. In the supplementary information, the species is classified as natural nesters, so the trend should be read as an indicator for the monitored natural-nesting population rather than a new full census of every breeding herring gull in Scotland.

The decline was also clear over a shorter long-term period. The 2024 abundance estimate was 43% below the 2000 level, again a statistically significant decrease.

The recent increase did not erase the long-term decline

More recent years showed a different direction. From 2015 to 2024, the herring gull index increased by 14%, one of the stronger short-term increases among the 14 species assessed for abundance. NatureScot did not test these short-term changes for statistical significance, so the increase does not overturn the much larger and statistically supported decline since 1986.

The annual indicator is not the same as Seabirds Count, the multi-year census designed to cover colonies across the UK. NatureScot uses the census as a benchmark, while the annual monitoring tracks how breeding abundance changes between census periods. In 2024, the Scottish abundance indicator drew on 222 colonies across all 14 species.

Sources and image credit

  1. Scottish Biodiversity Indicator - Abundance and productivity of breeding seabirds in Scotland 1986 - 2024Primary NatureScot indicator released in August 2026. For herring gull, 75 colonies and breeding numbers of 37,349 are listed. The abundance index was 54% below 1986 and 43% below 2000, both significant declines; the 2015–2024 change was +14%, and NatureScot notes that short-term changes were not tested for significance.
  2. Scotland’s seabirds under threatOfficial NatureScot release dated 13 August 2026 announcing the updated Scottish Seabird Indicator.

Image: Adult European herring gull (Larus argentatus) on a nest in Dornoch, Scotland, 12 May 2008. Photo: John Haslam. Source: Wikimedia Commons / Flickr. CC BY 2.0. Representative Scottish nesting image; not a bird from the monitoring dataset. · CC BY 2.0 · Source

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