By Helen Briggs BBC News
12 March 2018
Scientists are warning of the risks of wild birds spreading diseases when they gather at feeders in gardens.
Experts led by Zoological Society of London say people should continue to feed birds, especially in winter, but should be aware of the risks.
If birds look sick, food should be withdrawn temporarily, they say.
The review of 25 years' worth of data identified emerging threats to garden birds. Finches, doves and pigeons are vulnerable to a parasite infection.
Meanwhile, a form of bird pox is becoming more common, causing warty-like lumps on the bodies of great tits and other birds.
Other disease threats, such as salmonella, appear to be declining.
"Our study shows how three of the most common diseases that affect British garden birds have changed both dramatically and unpredictably over the past decade, both in terms of the species they affect and their patterns of occurrence," said Dr Becki Lawson from ZSL's Institute of Zoology.