Malaria is killing off a growing number of British birds including sparrows, chaffinches, owls and nightingales, experts say.
They believe the tropical disease is on the rise because the mosquitoes that spread it have benefited from the country's warmer and wetter climate.
Malaria rates among great tits have increased by five fold in the last ten years.
Thirty per cent of UK house sparrows are affected with malaria now, compared with under ten in 1990.
Meanwhile two thirds of the country's 38,000 tawny owls have been hit - as opposed to just one in 40 that had the disease in 1996.
The disease, which is brought into the country by infected migratory birds, cannot spread to humans.
"It is not always fatal as many birds have resistance to it, but if we get new strains and new types of mosquitoes it poses an increasing hazard to an already declining population," the Daily Mail quoted Grahame Madge, of the Royal Society for the Protection of Birds, as saying.
"Climate change is bringing warmer weather conditions that are likely to favour the colonization of some insects to our shores that cannot survive at the moment, and that could bring an upsurge in disease," she added.
The study has been published in the journal Global Change Biology.