LONDON, Dec. 5 (Xinhua) -- Many of Britain's rare breeding birds are at a high risk of extinction because of climate change, the wildlife charity Royal Society for the Protection of Birds (RSPB) said Tuesday.
In its annual "state of the birds" report, the charity says the changing climate could make Britain's climate less suitable for some species.
The RSPB says migratory birds are now arriving in Britain earlier each spring and leaving later each fall.
The study highlights how many species are already being affected by climate change as birds respond to average summer temperatures in Britain having increased by nearly one degree Centigrade since the 1980s.
The report says: "Population declines of birds such as for the dotterel, whimbrel, common scoter, and Slavonian grebe have already been considerable."
However, the report contains better news for some birds.
Some species such as little bittern and zitting cisticola may colonise southern Britain as their home in continental Europe becomes too warm and dry.
The lead author of the report, Daniel Hayhow, said: "Familiar species such as swallows and sand martins are changing their migratory behavior, distributions are changing and numbers of many species are increasing."
He said one of the most compelling revelations is how birds have adapted their behavior in response to warming temperatures.
One of Britain's most familiar summer visitors, the swallow, which migrates to and from southern Africa each year, is arriving back in the UK 15 days earlier and breeding 11 days earlier than it did in the 1960s. Swallows and other migratory birds, such as garden warblers and whitethroats are also delaying their return migration each autumn with some species now spending four weeks longer in the UK each year.
One of Britain's most familiar resident garden birds, the great tit, is also laying its eggs 11 days earlier than it did 40 years ago.
"These are obvious and major changes that show that even our common wildlife is already being affected by climate change," says the report.
Patrick Lindley, senior ornithologist for Natural Resources Wales said: "Birds are a great indicator to the health of our environment. The report presents a snapshot of the impact changing climate is having on birds within the UK."
Michael Morecroft from Natural England said: "Climate change is undoubtedly going to be one of the greatest influences, both positive and negative, on the future status of birds and other biodiversity in Britain."