The diet of Common Guillemot Uria aalge chicks provides evidence of changing prey communities in the North Sea

Helen Brenda Anderson, Peter G. H. Evans, Jacqueline M. Potts, Michael P. Harris, Sarah Wanless

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26 Citations (Scopus)


Local differences in feeding conditions have been suggested as a cause of regional variation in seabird demography but multi-colony comparisons of diet are rare. In UK waters the main fish eaten by seabirds during the breeding season belong to three families: Ammodytidae, Clupeidae and Gadidae. Climate change and fishing are affecting these fish stocks and so probably impact on predators such as seabirds. We used standardized observations of prey brought in for chicks to make the first integrated assessment of the diet of Common Guillemot Uria aalge chicks at a UK scale. Chick diet varied markedly among the 23 colonies sampled between 2006 and 2011. Sandeels (Ammodytidae), probably Lesser Sandeels Ammodytes marinus, were the commonest prey. Their contribution to the diet varied both latitudinally and among marine regions, with the proportion significantly higher for a given latitude on the west coast compared to the east. The non-sandeel component of the diet showed latitudinal changes, with small clupeids, probably Sprats Sprattus sprattus, predominant at southern colonies whereas juvenile gadids were the main alternative to sandeels in the north. Comparison of our Guillemot chick diet with data collected 15–30 years earlier suggests that the proportion of sandeels in the diet has decreased at colonies bordering the North Sea. No significant change was apparent in Atlantic colonies but historical data were limited. The early years of our study coincided with a population explosion of Snake Pipefish Entelurus aequoreus in the Northeast Atlantic and North Sea. Pipefish were recorded in Guillemot chick diet at several northern and northwestern colonies in 2006 and 2007 but have been absent since 2009. Spatial and temporal variation in chick diet accorded broadly with patterns expected as a result of rising sea temperatures and impacts of fishing. Guillemot chick diet could potentially be a useful indicator of changes in the distribution and abundance of forage fish.
Original languageEnglish
Pages (from-to)23-34
Number of pages12
Issue number1
Early online date3 Oct 2013
Publication statusPublished - Jan 2014

Bibliographical note

Many people and organizations helped directly and indirectly in this project. Particular thanks are due to Shirley Lam, Martin Heubeck, Sarah Money, David Jardine and members of the Colonsay Ringing Group. Additional help was provided by Vicky Anderson, Kate Ashbrook, Jakob Assam, Craig Bloomer, Mark Bolton, Helen Booker, Ashley Bunce, David Campbell, Rachel Cartwright, Amy Corton, S. Dalrymple, Adrian del Nevo, Ronnie Dyer, Keith Emery, Derren Fox, Patricia Harbinson, Jo Hulsman, Ray Johnson, Roddy Mavor, Mick Mellor, Ian Mitchell, Lisa Morgan, Mark Newell, Miranda Shephard, Grant Sherman, Chris Thaxter, RSPB, JNCC, SNH, SOTEAG, NTS, SWT, the Hebridean Trust and the Macaulay Institute. Sue Lewis, Norman Ratcliffe, René Van der Wal, David Elston, Bob Swann, Paul Fernandez, Maria Bogdonova, Peter Wright, John Pinnegar and two anonymous referees provided valuable comments and advice on earlier drafts of the manuscript.


  • climate change
  • forage fish
  • multi-colony comparison
  • Northeast Atlantic
  • North Sea
  • Sandeel
  • Snake Pipefish
  • Sprat


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