Isle of May seabird studies in 2001

Wilson, L. J.; Wanless, S.; Harris, M. P.. 2002 Isle of May seabird studies in 2001. Peterborough, JNCC, 27pp. (JNCC Report 328)

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The 2001 season for seabirds on the Isle of May was characterised by high interspecific variation, particularly in breeding success. Thus some species had their most productive season since monitoring began, while others had their least productive. Timing of breeding in auks and Northern fulmars was normal, while European shags and black-legged kittiwakes laid later than in recent years. Return rates were generally close to or above the long-term average, except for common guillemots which were lower. Sandeels and clupeids were the predominant prey items, but varied in importance between species. European shags had an excellent breeding season. Although breeding started later than in 2000, overall breeding success (1.53 chicks per incubated nest) was the highest recorded since intensive monitoring began in 1986. Atlantic puffins had their most successful season for four years and breeding success (0.78 chicks per pair laying) was above the long-term average. In contrast, common guillemots had the lowest breeding success since monitoring began in 1986 (0.63 chicks per pair laying). Some chicks were neglected and fledging weights were considerably lower than the long-term average. Razorbill breeding success (0.60 chicks per pair laying) was lower than the long-term average. Black-legged kittiwakes started breeding later than in recent years. Losses were high during incubation but few failures occurred during chick-rearing. Thus overall breeding success (0.61 chicks per pair laying) remained above the long-term average, although not as high as in 2000. Northern fulmars had a very poor season, with breeding success estimated at only 0.26 chicks per incubating pair, well below the long term average. The return rate of colour-ringed European shags (89.8%) in 2001 was similar to that in 2000. Black-legged kittiwake return rate (81.2%) was the highest since 1990. The return rate of common guillemots (82.9%) was slightly below the long-term average whereas razorbill and Atlantic puffin return rates (82.9% and 90.5% respectively) were much higher than in 2000. Sandeels predominated in the diet of European shags, black-legged kittiwakes and Atlantic puffins in 2001. In contrast to 2000, well over half of common guillemot chick diet was made up of clupeids, which also predominated in razorbill chick diet. As in 2000, there was no commercial sandeel fishery on the Wee Bankie. Results for 2000 provided circumstantial evidence that the presence of an industrial fishery on the Wee Bankie was having an adverse effect on some components of the Isle of May seabird community and that closure of the fishery could potentially have an immediate and positive effect on seabird productivity. In particular, black-legged kittiwake breeding success returned to the high levels typical of the pre-fishery period. In 2001 breeding success of the two species with the highest reliance on sandeels (black-legged kittiwake and European shag) continued to be above the long term average, although black-legged kittiwake performance in 2001 was not maintained at the 2000 level. Atlantic puffins, although less reliant on sandeels, had a very successful season. Common guillemots and razorbills which both fed their chicks predominantly on clupeids, and Northern fulmars, for which sandeels do not appear to form an important part in the diet, all had poor seasons. It was uncertain in 2000 whether environmental factors, e.g. hydrographic conditions, that potentially affect the growth and life history strategy of sandeels, were involved in the recovery of the breeding success of European shags and black-legged kittiwakes. A new EU-funded interdisciplinary project was started in 2001 to investigate this further.

Item Type: Publication - Report
Programmes: CEH Programmes pre-2009 publications > Biodiversity
UKCEH and CEH Sections/Science Areas: _ Population & Conservation Ecology
Funders/Sponsors: Joint Nature Conservation Committee
Additional Keywords: Isle of May, Seabirds
NORA Subject Terms: Zoology
Date made live: 09 Mar 2009 15:53 +0 (UTC)

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