Oil Spills And Climate Change Double The Mortality Rate Of British Seabirds

A team led by Professor Tim Birkhead from the Department of Animal andPlant Sciences at the University of Sheffield, shows for the first timethat major oil spills double the mortality rate of adult guillemots inBritain, even though the pollution occurs hundreds of miles from thebirds' breeding grounds. The research, which is to be published in theNovember issue of Ecology Letters also shows a direct link between awarmer climate in the North Atlantic and a higher mortality rate amongBritish guillemots.

Professor Birkhead's long-term guillemot study has been carried out onSkomer Island, Wales, since 1972. The length of the ongoing study hasallowed the research team to study the effects of a number of seriouswinter oil spills on the guillemot population. Their findings show thathighly publicised oil spills in southern Europe, such as the Prestigeoil tanker disaster off the coast of Galicia, Spain, in November 2002,have far-reaching consequences on seabirds breeding far from the sceneof the initial pollution.

The study has also found that consistently high values of the NorthAtlantic Oscillation (NAO) index (an annual measure of a large scaleclimatic phenomenon affecting winds, temperature and rainfall) for thepast 30 years, has had a negative effect on the guillemot population ofSkomer Island.

Professor Tim Birkhead of the University of Sheffield said: "Prior toour investigation of the guillemot population of Skomer Island, theimpact of oil pollution on seabird mortality rates at a particularcolony was difficult to quantify as oil spills usually occur inwintering areas where birds from many different colonies may bedistributed over a wide area. However, our long-term monitoring ofindividually marked birds on Skomer Island has enabled us to see adirect correlation between major oil pollution events and a twofoldincrease in winter mortality rates of common guillemots.

"Our research has also shown that the NAO index has had a significanteffect on the guillemot population. The consistently high values ofthis climatic phenomenon for the past 30 years may be due tohuman-induced global climate change. If this is the case, it would meanthat seabirds are vulnerable to human activities on two counts: oilpollution from tanker spills and changes to the ecosystem as measuredby the NAO index and caused by global climate change from man's burningof fossil fuels."