Global warming is claiming its first real victim in Britain's wildlife - the blackbird of the mountains.
Research is linking a sharp decline in the population of the ring ouzel, a close blackbird-relative which lives on cool mountain tops and high moors, to rising atmospheric temperatures.
Numbers of the attractive bird - its black plumage is broken by a striking white crescent around its breast - have dropped by almost 60 per cent in the past decade, in Scotland and in the English and Welsh moorlands.
Scientists fear higher temperatures in late summer, prompted by climate change, are causing the birds in northern England, the Peak District, north Wales and the Brecon Beacons to disappear completely.
They have already gone from the Long Mynd, a ridge of high ground in south Shropshire, where there were 12 pairs in 1999. In Dartmoor and Exmoor they used to be plentiful, but now there are only a handful left.
"We think that ring ouzels in England and Wales are being hardest hit by the warmer temperatures," said Colin Beale of the Macaulay Land Use Research Institute in Aberdeen, who led the research, published in the Journal of Animal Ecology.
"They just seem to be dying out rather than adapting and moving elsewhere. But that isn't to say there isn't hope for them. We think that it is changes in the availability of food, rather than higher temperatures themselves, that is the problem, and we may be able to do something to help."
Ring ouzels are elusive birds best known to hikers, mountaineers and hill walkers. They spend the winter in Spain and Africa and migrate back to Britain every spring.
Although the effect of climate change on British wildlife has already been observed in various ways, such as flowering times, the ring ouzel is the first case where a whole population of a species has been seen to be at risk.
"It's the only species so far where a natural decline of any magnitude has been demonstrated, and where in our view climate change is the underlying cause," Dr Beale said.
Scientists from the Royal Society for the Protection of Birds are starting this week to radio-track ring ouzels in the Scottish Highlands, to follow their movements and learn more about their habits and needs. They fear that dry ground caused by warmer weather means earthworms are more difficult to find, and may also affect berry crops, staple foods on which the birds rely. This could be leaving the birds in poor condition for their autumn migration to Spain's Sierra Nevada and the Atlas Mountains of Morocco and Algeria, and in turn meaning that fewer survive to return.
Dr Beale said: "If we change the management of moors so that heather grows larger, there may then be more moisture left in the soil. That means earthworms will be nearer the surface and therefore more food available."
Jerry Wilson, an RSPB scientist, said: "The ring ouzel is one of the UK's least studied birds, which is why this new research is so vital. We are hoping tagging will tell us what they feed on and which habitats they use. The findings could be crucial in improving management of upland areas for ring ouzels and protecting them from climate change."Reuse content