(AP) -- Britain's cuckoo bird, known for its distinctive call, is in danger of extinction along with 51 other species, the Royal Society for the Protection of Birds said in a new report Thursday.
It found that 21 percent of Britain's bird species face extinction unless steps are taken to protect them, spokesman Tim Webb said. He said the cuckoo and other birds that visit Britain in the summer have suffered population loss largely due to a decrease in food and water supply in sub-Saharan Africa, where many migrate from.
The problem is difficulty in finding food, he said.
"The Sahara desert is spreading and the birds are having a hard time flying out in good condition," Webb said. "There isn't just one single problem, there are a host."
The society said the cuckoo population in Britain has declined 37 percent since 1994.
The population declines were not limited to summer migratory birds like cuckoos. Native birds such as the herring gull also made the threatened list.
Six species did see a recovery in the past seven years, however. The report said the woodlark has seen a "dramatic" increase in population, as had the stone-curlew. Webb said these birds saw healthy gains thanks to an increased effort to maintain woodlands that would allow their numbers to grow.
Webb said the inclusion of such well-known birds as the cuckoo and herring gull on the list could serve as an eye-opener to people who are unaware of the decline in bird population.
"Everyone thinks they are always there," he said of the birds. "They didn't think that such common birds would be struggling, and if nothing changes we will see them disappear."
©2009 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
Explore further: How rockstars and peacocks attract the ladies