NEW research published today shows that Scotland’s seabird populations are now, on average, around half the level they were in the 1980s.
Numbers are continuing to decline, with some species now at a fraction of the populations recorded when systematic monitoring began in 1986.
New figures from NatureScot show that seabird numbers around Scotland’s coast are now, on average, around half what they were in the 1980s.
The latest Scottish Biodiversity Indicator assessed 19 of the 24 seabird species that breed around Scotland’s coasts, using data collected between 1986 and 2024.
Almost all of the species assessed have declined over the long term, with eight showing statistically significant decreases.
The worst affected is the Arctic skua, whose numbers have fallen by 93% since 1986. Little tern numbers are down 75%, while common tern populations have fallen by 73%.
Other significant long-term declines include a 70% fall in shag numbers, a 59% fall in great black-backed gulls, a 53% decline in kittiwakes and a 54% decline in herring gulls breeding in natural habitats.
There is currently no Scottish seabird species in the latest assessment showing a significant long-term increase.
However, the figures aren’t uniformly negative. NatureScot says breeding success for black-headed gull, guillemot and puffin has stabilised over the most recent three years of the assessment, from 2022 to 2024.
Gannets and great black-backed gulls also had better-than-average breeding success in 2024, although the long-term picture for gannets has been affected by the impact of avian flu.
That distinction is important. A species can have a good breeding season without having recovered from decades of population decline.
The latest figures therefore aren’t saying that every Scottish seabird colony is collapsing year after year. They show that the long-term direction remains overwhelmingly negative for many species.
What’s causing the decline in Scotland’s seabirds?
There isn’t one straightforward answer. Seabird populations are affected by the availability of food, weather, predation and conditions at sea, while climate change is altering the marine environment on which they depend.
Highly pathogenic avian influenza has added another major pressure in recent years.
The impact of bird flu has been particularly severe for some species. Arctic skua, already Scotland’s most dramatically declining seabird in the latest figures, had an exceptionally poor breeding season in 2024, producing an estimated 0.03 chicks per pair. Great skua productivity was also low at 0.17 chicks per pair.
Food availability can have an immediate effect on breeding success, too. NatureScot says annual fluctuations in breeding success reflect factors including food availability, weather events and predation. The problem is that seabirds don’t experience these pressures independently.
A colony can be affected by changes in the availability of prey at sea, extreme weather during breeding, predators on land and disease. Several pressures can therefore be acting on the same population at the same time.
Seabirds are a major part of the wildlife people encounter on Scotland’s islands and cliffs, and the health of their populations is one indication of what is happening in the wider marine environment.
The fact that the monitoring stretches back to 1986 is particularly valuable. It means this isn’t a comparison between one good year and one bad year. Researchers have almost four decades of data against which to measure the change.
And that makes the scale of some of these declines difficult to dismiss.
An Arctic skua population that is 93% smaller than it was when monitoring began isn’t experiencing a temporary wobble. It’s a fundamentally different population.
What happens next?
NatureScot says work is already underway through the Scottish Seabird Conservation Action Plan, with efforts focused on safeguarding food supplies, restoring habitats and improving seabird survival.
It also stresses the importance of continuing long-term monitoring and using new technology to improve understanding of seabirds. That monitoring will be crucial.
The latest figures give Scotland a much clearer picture of where its seabirds stand after nearly 40 years of observation. They also show that, despite some encouraging signs in recent breeding success, the overall long-term picture remains deeply concerning.
Scotland’s seabirds haven’t simply had a bad couple of years. For many species, the decline has been happening for decades. And for the Arctic skua, little tern and common tern, there is now very little of the population left compared with 1986.
The question is whether the measures now being taken can turn those numbers around before today’s declining species become tomorrow’s conservation emergencies.
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