Birds started moving northwards 25 years ago

31/07/2008 09:11:44 July 2008. A study of the rarest birds in the UK has discovered that climate change has had a noticeable impact on population levels for the last 25 years.

Scientists from the RSPB and Durham and Cambridge Universities studied nesting patterns from 42 of the UK's rarest nesting birds from1980 and 2004; they discovered that some species with a southerly distribution are faring better in the UK, while species whose distributions are centred further north are struggling.

Cetti's warbler & Little egret
The best examples include the little egret and the Cetti's warbler, two birds that colonised the south of Britain in 1996 and 1972 respectively. The latest population information for both species shows they are doing phenomenally well, with maximum populations of 433 of little egret and 1331 pairs of Cetti's warbler nesting in the UK. Other winners include the cirl bunting and the Dartford warbler, both more numerous in Spain than in the UK.

Redwing decline
Conversely, the redwing - a type of Scandinavian thrush - is faring badly. The redwing is a widespread visitor to the UK in winter, but as a nesting bird it only colonised the UK in 1925, reaching a peak of up to 80 pairs in the 1980s. Subsequently, the paper shows that the population of this ‘northern' thrush has declined sharply to a just few pairs.

Dr Richard Gregory, of the RSPB, is one of the paper's authors. He said: "Our paper clearly shows that wildlife has been affected by climate change over the last 25 years - some nature reserves in southern Britain now have an almost ‘Mediterranean' feel to them. Many scientists have used models to predict the future changes in distribution of species responding to climate change, but our paper shows that wildlife has been responding to a changing climate for a quarter of a century at least. This discovery has profound consequences for some of our most threatened and declining wildlife and shows that climate change is likely to continue to have an overwhelming impact on the threatened species."

Little egret, credit Jodie Randall (rspb-images.com)

Expected results
Professor Brian Huntley from The Institute of Ecosystem Science at Durham University added: "The results are what we expected to find given the changes in climate over the last 20 years. Because the UK is in the middle Latitudes of Europe, we expected that recent climatic warming would favour species with ranges located in the south of Europe and adversely affect northern species."

550 KM shift northwards
The authors, using the same climate models, published a Climatic Atlas of European Breeding Birds earlier this year. This work showed that, on average, suitable climates for European birds are likely to shift northwards by 550km - a distance equivalent from Plymouth to Newcastle.

The paper is published in the Royal Society journal Biology Letters.