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24 October 2008
I've seen birds with growths on their heads, bottoms and necks. Is this harmful to them?
Sent in by Angela Pilbeam, Surrey
Kirsi Peck, Wildlife Adviser
Kirsi answers...
Though we can't be sure, the growths you describe are probably caused by avian pox. This is a viral skin disease that causes reddish-brown lesions. When the lesions are small, they can be confused with a tick infestation.
They seem not to cause a bird too many problems, and in theory, a bird may recover from the infection and become immune to it. Larger lesions can be 2-3 cm across. These tend to affect the bird's ability to fly, eat or see, and a bird affected by this is unlikely to survive for long.
Avian pox is a bird-specific disease, which does not pass onto people or pets. It is in the same group of viruses as the one causing chicken pox in humans. Like chicken pox, it is highly contagious, and is spread by the pox lesions.
While it is a relatively uncommon infection, we have received a number of reports of avian pox this summer and autumn. Most people have reported affected great tits, but some also blue tits and dunnocks.
There are different strains of avian pox, each of which tend to infect certain species, which may be why there have been no reports of the infection in finches, for instance.
What you can do
Whenever birds with pox lesions appear at feeders, feeder hygiene is especially important. Clean the feeders every time you fill them, and pay particular attention to the perches and the seed ports.
Avian pox is one of the many garden bird diseases that the RSPB is monitoring. If you see birds of any species with growths on them, you can help us with our work by getting in touch with the Wildlife Enquiries team. We would need to know what kind of bird is involved, how many have shown symptoms, as full a list of symptoms as possible, when you found the first affected bird, and your postcode so we can map the report alongside others.
About Kirsi
I have a life-long interest in wildlife and birdwatching. Having completed my PhD on woodland birds, I joined the RSPB in 1990, first as a member of the research department, later in Wildlife Enquiries. I write and manage many information leaflets, and have extensive knowledge of bird biology, habitat management, wildlife law, planning and many other subjects.
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