The most comprehensive census of seabirds in the UK and Ireland has found half our species have declined in the past 20 years.
The Seabirds Count, led by the Joint Nature Conservation Committee (JNCC) with over 20 partners including the UK Centre for Ecology & Hydrology (UKCEH), provides population estimates for species that regularly breed on our shores.
The latest census, which took place between 2015 and 2021, showed that 11 of the 21 seabird species where there is confidence in their trends have declined since the previous census in 1998-2002. Five species have remained stable and five have increased.
Species that declined included the Puffin, whose numbers fell 24% after positive trends in the previous three surveys, as well as the European Shag (down 20%), Kittiwake (-42%), Northern Fulmar (-35%) and Common Gull (-49%).
The causes of decline vary between species and regions but are likely linked to
• Adverse weather conditions, associated with climate change, which cause nest sites to be swept away and make foraging conditions difficult.
• A lack of food as a result of both rising water temperatures, which affect the marine food web, and commercial fishing.
• Predators, some of which may have been released onto seabird colony islands or, in the case of Brown Rats and American Mink, may have arrived after hiding away on boats.
Populations of some colonies grew thanks to successful conservation action such as predator eradication programmes and site protection.
Professor Francis Daunt of UKCEH is an author on two of the chapters, on Kittiwakes and European shags, in the upcoming book on the census. He says: “Our seabirds are facing several challenges which have reduced survival and breeding success of many colonies in the past few years. For example, climate change and commercial fishing have affected the availability of seabirds’ traditional food sources such as sandeels.”
Mark Newell, who leads UKCEH’s long-term seabird monitoring on the Isle of May in the Firth of Forth, adds: “The situation is particularly concerning in Scotland, where declines have been most severe in the UK.
“Avian Flu has exacerbated the pressures on seabird populations in UK and Ireland. The census, which was completed just before the start of the pandemic in 2021, will provide an important baseline to help us understand the impacts that flu has had on colonies.”
Avian Flu has resulted in high mortality rates in several previously increasing seabird species such as the Great Skua, Northern Gannet and Roseate Tern. Analysis by the Scottish Seabird Centre, the University of Edinburgh and UKCEH found populations of the largest Northern gannet colony on Bass Rock, has reduced by 25-30% since the last major survey in 2014.
There are more details about the Seabirds Count on the JNCC website.