Tracking terns

Novel methods identify important marine areas for the five tern species breeding in the UK


With 119 bird species making significant use of the marine environment around the UK, JNCC’s Seabirds and CetaceansCommon Tern (Sterna hirundo) ©Mark Lewis team are working to compile a coherent network of marine protected areas to support future generations of these birds. Such protection areas are only a small part of the efforts required to halt the unprecedented rate of biodiversity loss being experienced.


The five species of tern breeding in the UK - Arctic tern, common tern, Sandwich tern, roseate tern and little tern - are long-distance migrants, wintering along the coasts of west Africa, or in the case of Arctic tern, the oceans of Antarctica. The latter two species are among the rarest seabirds breeding in Great Britain. All five terns are listed on Annex I of the EU Birds Directive and therefore the UK is required to classify Special Protection Areas (SPAs) for them.


Currently there are 57 SPAs for which at least one species of tern, as a breeding colony, is a qualifying feature. There are, however, currently no SPAs in the marine environment for these birds.


During the breeding season terns forage at sea within a restricted range around the colony as they return frequently to feed and brood their chicks. Food availability within the foraging range of breeding colonies is crucial to breeding success, so since 2007 JNCC has been working with the Countryside Council for Wales (now Natural Resources Wales), Natural England, the Northern Ireland Environment Agency and Scottish Natural Heritage to identify important foraging areas at sea used by terns for consideration as marine SPAs.


In order to identify these foraging areas for the four larger species of tern, a novel visual tracking method has been used to collect data at selected colonies around the UK. Individual terns were followed in a rigid inflatable boat as they went on foraging flights during the breeding season. A cutting edge habitat modelling approach developed in collaboration with statisticians then allowed the surveillance team to make predictions of foraging distributions around unsampled colonies.


A simpler approach to defining a generic foraging extent has been applied to little terns as these forage very close to shore and to their breeding colony.


A workshop with the country nature conservation bodies at the start of the year, followed by a quantitative model assessment, has led to a strong degree of confidence in the models and a positive outlook for the tern project as a whole, with minor model refinements and boundary delineation remaining.


The aim is to finalise a suite of suitable marine areas for consideration as possible marine SPAs by December 2013 and to publish a report on the work on the JNCC website early next year.



Contact File


Julie Black & Ilka Win

Senior Seabird Ecologist/Seabird Ecologist

Tel: +44 (0) 1224 266566/ 266569


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