Mystery of birds’ movements at sea solved

Louise Cullen

Friday 7 July 2017

  • New research reveals where British and Irish seabirds go when they're not on land.
  • The five year project GPS-tracked over 1,300 breeding seabirds and used computer models to predict where they go to find food.
  • Results reveal the majority of 'hotspots', where seabirds gather to feed, are concentrated in the coastal waters of Scotland, highlighting the need for robust conservation measures in this area.
  • The new maps will be used to protect threatened species by assessing potential impacts from offshore wind farms, pollution and other human activities on seabirds.

New research has identified the most important areas for Britain and Ireland's seabirds at sea, with the majority of 'hotspots' revealed in the coastal waters of Scotland.

Experts used GPS-tracking (1) and computer models on an unprecedented scale to map where breeding seabirds go when they leave land to feed, providing a unique insight into the lives of these enigmatic birds.

The study (2), headed by the RSPB in partnership with over a dozen scientists from leading research institutes (3), used five years of tracking data to estimate the areas used by four species: kittiwakes, shags, razorbills and guillemots.

This comes as the Scottish Government considers the creation of Special Protection Areas at sea to safeguard key seabird feeding areas, as well as planning future management of marine activities in Scottish waters outside of the EU and the Common Fisheries Policy.

During the project, lightweight GPS tags were fitted to over 1,300 adult birds from 29 different colonies. The tracking data was then used to create a computer model for each species, so that all of the important areas at sea could be predicted.

The results (see study maps attached) show the extent to which birds travel to find food. The majority of seabird 'hotspots', where different species gather to feed, are concentrated in the coastal waters of Scotland, highlighting the need for robust conservation measures to protect these areas. Overall, the four species use at least 1.5 million square km of sea around Britain and Ireland - an area three times the size of Spain.

This is a major step forward in our understanding of seabirds and is a powerful tool to help protect birds from potentially harmful activities at sea, including helping to make better decisions about where those activities can be undertaken to limit their impacts on seabirds.

Understanding more about our seabirds is vital because they are one of the most endangered groups of birds in the world. Over the last 30 years, kittiwake and shag numbers have declined by 72% and 68% respectively in Scotland. This is partly due to the impacts of climate change and fishing, and a new OSPAR report (4) underlines this trend, highlighting widespread seabird breeding failures in the North and Celtic Seas. Scotland is also home to internationally important populations of breeding seabirds so we have a global responsibility to safeguard them.

Dr Mark Bolton, RSPB Principle Conservation Scientist, said: "Our rich and diverse marine environment makes Britain and Ireland one of the greatest areas in the world for seabirds and this new research is further evidence of just how important our seas are for seabirds and their chicks during the breeding season. In order to strengthen this research and our predictions, there is an urgent need for a complete seabird census which will provide an accurate and up-to-date estimate of the size of our seabirds breeding colonies."

Dr Ellie Owen, who led on the tracking work, said: "The sight and sound of hundreds of thousands of seabirds flocking to our shores is an amazing natural spectacle and something that we must help protect for future generations to enjoy. The methods used in this study could be applied to other seabird species, to show where they go at sea. This will be an invaluable tool in helping to protect seabirds, as it will greatly improve our ability to assess the likely impacts on breeding seabirds of offshore wind farms, oil spills and other potentially harmful activities in our increasingly industrialised seas."

Dr Ewan Wakefield, lead author of the research, said: "Many seabirds are at the top of the marine food web. They feed on sandeels and other small fish but that prey is declining because of human pressures, including climate change. The result is that thousands of seabird chicks are dying each year because their parents can't feed them. For the first time, this study provides us with a full map for each breeding colony of the feeding areas for some of our most important seabird species. That means we can now protect the places these birds catch the fish they need to feed their hungry chicks, securing the fate of future generations of these amazing creatures."

Until recently, seabirds could only be mapped at sea using boats or planes, but this method could not identify which colony each bird was from. Using GPS tracking allows scientists to follow individual birds, revealing exactly where they have come from and where they go at sea to forage.

The research has been published in the leading science and conservation journal Ecological Applications. To access a copy of the paper click here. Full citation of the paper: Wakefield, E. D., Owen, E., Baer, J., Carroll, M. J., Daunt, F., Dodd, S. G., Green, J. A., Guilford, T., Mavor, R. A., Miller, P. I., Newell, M. A., Newton, S. F., Robertson, G. S., Shoji, A., Soanes, L. M., Votier, S. C., Wanless, S. and Bolton, M., Breeding density, fine-scale tracking and large-scale modeling reveal the regional distribution of four seabird species. Ecol Appl. Accepted Author Manuscript.

This project was a huge team effort, involving more than a dozen scientists from leading research institutes. The project partners are: The Centre for Ecology and Hydrology; University of Liverpool; University of Oxford; University of Exeter; BioStatistics Scotland; Birdwatch Ireland; Sule Skerry Ringing Group. The partners involved in the FAME project: SEO; SPEA; LPO; Birdwatch Ireland; WaveEC; and Univeristy of Minho. The project was funded by seven organisations: EU Interreg Fund through its Atlantic Area program; Natural Resources Wales; Scottish Natural Heritage; Joint Nature Conservation Committee; Natural England; Marine Scotland; Argyll Bird Club.

OSPAR's intermediate assessment published last week of the state of the North Atlantic since last assessed in 2010 showed that: For the six-year period, widespread seabird breeding failures frequently occurred in 35 per cent of species assessed in the Greater North Sea, 25 per cent in the Celtic Seas and 44 per cent in the Norwegian parts of the Arctic Waters...a third of surface feeders in the Celtic Seas and half the surface feeders in the Greater North Sea showed frequent and widespread breeding failure during the six year study period. The OSPAR report linked these declines with climate change impacts on the availability of prey fish for seabirds, and also raised plastic pollution as a concern. OSPAR is the mechanism by which 15 Governments & the EU cooperate to protect the marine environment of the North-East Atlantic (https://www.ospar.org/).

For more information about the Seabird Tracking work: the FAME (Future of the Atlantic Marine Environment) and STAR (Seabird Tracking and Research) projects please click here

To track the birds, GPS tags were attached to adult birds during the breeding season (May- July) including 230 European shags, 464 black-legged kittiwakes, 178 common guillemots and 281 razorbills, breeding at 13, 20, 12 and 14 sample colonies respectively.

Only breeding seabirds were studied as we need to be able to catch the birds a second time to retrieve the tags and download the data (these tags don't transmit the data automatically). To have a reasonable chance of catching the same bird twice in a few days we need to work with birds coming back to nests. Non-breeding birds would be more difficult to catch initially and then very hard to catch the same birds again.

Tagged with: Country: Scotland Topic: Marine and water