Posted 12th March
Scientists have warned garden bird feeders could be leading to the spread of serious diseases among wild birds, with rare illnesses subsequently spreading and becoming more common problems
A combination of poor hygiene, an accumulation of droppings and stale food means garden birds are spreading illness - animals are congregating in the same location, and encountering species they don't usually come into contact with in the wild.
The study was conducted by Zoological Society of London, the British Trust for Ornithology (BTO), and Fera Science and analysed over 25 years of wild bird health data, which includes the RSPB's Big Garden Birdwatch, and found dramatic changes in bird populations, which scientists believe could have led to the disease spreading at bird feeding sites.
Kate Risely, from BTO, said: "We’re calling on everyone who feeds wild birds to be aware of their responsibilities for preventing disease. Simple steps we’d recommend include offering a variety of food from accredited sources; feeding in moderation, so that feeders are typically emptied every one to two days; the regular cleaning of bird feeders; and rotation of feeding sites to avoid accumulation of waste food or bird droppings".
The study focused on the protozoan parasite which is responsible for finch trichomonosis - this has been responsible for a 35 per cent drop in the greenfinch population in the British Isles, with numbers dropping from 4.3m to 2.8m since the disease emerged in 2005.
Lead author of the study, Becki Lawson, from ZSL's Institute of Zoology, said: "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."
"Both finch trichomonosis and Paridae pox have emerged recently, causing disease epidemics affecting large numbers of birds, while passerine salmonellosis – previously a common condition – appears to have reduced to a very low level. These conditions have different means of transmission – so deepening our understanding of disease dynamics will help us develop best practice advice to ensure that feeding garden birds also helps to safeguard their health."