Dirty bird feeders killing off garden species, study shows

LEAVING food out for the birds is one of the most satisfying ways to feel like you are helping nature.

But you risk killing them with kindness if you do not clean your feeder every day, experts warned, as dirty feeders were linked to declining chaffinch numbers for the first time.

Scientists at the British Trust for Ornithology and the Zoological Society of London found that trichomonosis, a parasitic disease first detected in British finches in 2005, is behind the decline of some of Britain’s most beloved garden birds.

Overall, the paper found a decline of around 2.5million breeding pairs of greenfinches, inset, and chaffinches.

The same organisations previously confirmed this in greenfinches, but the link with declining chaffinch numbers has not been made until now.

Scientists looked at the pattern in changing bird numbers over the past 15 years and found falls were driven by a drop in the survival rates of adult birds and also observed high levels of disease. The findings are based on reports of sick or dead birds made by the public to the Garden Wildlife Health project The greenfinch was moved to the UK Red List in the recent Birds of Conservation Concern review published last year. Survival rates were lowest in habitats where there was a lot of contact with humans, with places where many birds congregate at feeders thought to be the highest risk. The disease makes swallowing difficult and can cause the regurgitation of food, so shared sources of bird food and water can easily be contaminated. Other species including pigeons and doves are also affected. Scientists said people should regularly clean feeders and bird baths and rotate the locations of feeders around the garden to stop food waste building up. Feeding should be suspended if sick birds are seen.

Advice from Garden Wildlife Health suggests only leaving out enough food for 24 to 48 hours and throwing away any excess after that time. The study was published in