A FREQUENT visitor to British gardens is under threat from a mosquito-borne bird virus that is sweeping the country, say scientists.
Experts are worried about a new strain of avian pox which can cause life-threatening infections in great tits.
The virus is known to target a number of British bird species, including house sparrows and wood pigeons, but is especially harmful to the green and yellow songbird.
Wildlife vet Dr Becki Lawson, from the Zoological Society of London (ZSL), said: “Infection leads to warty, tumour-like growths on different parts of a bird’s body, particularly on the head around the eyes and beak.
“Although the disease can be relatively mild in some species, great tits suffer severe growths that can prevent them from feeding and increase their susceptibility to predation.”
Scientists from Oxford University observed the effects of the virus in birds in nearby Wytham Woods. They found that while a range of tits were susceptible, the great tit was by far the most seriously affected.
Dr Shelly Lachish, from the university’s Edward Grey Institute, said: “Although recovery from infection can occur, our results show that this new strain of avian pox virus significantly reduces the survival of wild great tits.
“Based on the numbers of affected great tits that we have observed at Wytham Woods, our models do not predict that this new disease will cause an overall population decline of the species. However, pox-affected populations have lower yearly growth rates.”
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