Experts warn of garden bird disease
A bird disease which can leave great tits riddled with lesions, stopping them feeding and leaving them vulnerable to predators, is spreading across the UK, researchers have warned.
Members of the public are being asked to look out for garden birds that have signs of avian pox, a virus which could be transmitted through contaminated bird feeders as well as direct bird-to-bird contact and through biting insects.
Researchers said the disease has been known in common species including woodpigeons, house sparrows and starlings in the UK since the 1960s.
But since 2006 it has been spreading through great tits in south-east England, and less commonly in other garden favourites including blue tits and coal tits, said the Zoological Society of London (ZSL).
Multiple birds are being affected at individual sites, said ZSL's wildlife vet Dr Becki Lawson. And while the avian pox virus - which leads to warty, tumour-like growths on birds, particularly on the head around the eyes and beak - can be relatively mild in some species, it can provoke severe symptoms in tits, she said.
"The lesions can be really rather severe. Remarkably the birds can be bright and active, but if the lesions interfere with ability to feed or flight, it could make them very vulnerable to predators," she said.
Affected birds had previously been spotted mostly in Surrey, Kent and Sussex, but Oxford University scientists have now detected the disease in great tits in Wytham Woods - and ZSL believes the pox may have spread as far as Staffordshire.
Professor Ben Sheldon, of the university's Edward Grey Institute, said: "We have been studying great tits at Wytham Woods near Oxford since 1947 - the longest-running study of its kind in the world, so we were very concerned when we first detected this disease in 2010. We're using our detailed observations to try and understand how this new form of pox affects survival and reproductive success."
Researchers from ZSL are conducting molecular analysis of the avian pox virus to see if it is a new strain and whether it is linked to the emergence of the disease in great tits on the continent. And they are asking the public to look out for evidence of lesions on birds in a bid to see how much it is spreading in the UK.
People who see birds which are displaying symptoms of avian pox should report their sightings to the RSPB Wildlife Enquiries Unit on 01767 693690 or online.