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Avian pox in garden birds
Avian pox is a viral skin infection that shows up as unsightly growths on the bird, mainly on the head and neck, and at the base of the wings.
Which birds are affected?
Avian poxvirus infections have been reported sporadically in British garden birds, mainly wood pigeons and dunnocks, for many years.
Since 2007, there have been reports of pox lesions in tits, mostly great tits, particularly during the late summer and autumn months. It is common for a number of tits to be affected in one garden, and their lesions can be quite severe.
The extent to which different bird species are susceptible to different strains of avian poxvirus is unknown. However, the disease could potentially be infectious to poultry, cage and aviary birds. Avian pox is found only in birds, and so it does not pose a threat to the health of humans or other mammals, such as cats and dogs.
What happens?
Affected birds develop warty or tumour-like growths, on the head (particularly next to the eyes or beak), legs, wings, or other body parts. The growths are usually grey, pinkish, red or yellow in colour. Affected birds often appear to feed and move around normally.
In many species, including wood pigeons and dunnocks, the growths can be relatively mild and may regress with time. However, in some cases, especially in tits, the growths can become very large and may impede the ability of birds to see, feed or move around. In these cases the birds become more susceptible to predation and other infections.
Although large pox growths can be very characteristic, smaller or medium-sized growths can easily be confused with a number of other conditions, including ticks. The disease can only be confirmed by further investigation, such as post mortem examination and subsequent laboratory analysis.
How is it passed on?
Avian poxvirus is thought to be spread between birds in three main ways:
• by biting insects (e.g. mosquitoes, mites and flies)
• by direct bird-to-bird contact
• by indirect contact via contaminated surfaces such as perches or bird tables.
The virus is relatively resistant and can persist on contaminated surfaces, such as perches and bird tables, for long periods of time.
What can I do?
Whilst supportive care can be attempted in captive birds, there is no treatment that could be given to free-living birds.
Where an avian poxvirus outbreak exists, general measures of disease control in wild bird populations should be adopted. Ensure optimal hygiene at garden bird feeding stations, paying particular attention to regular disinfection of surfaces that the affected birds have been in contact with, such as perches and feeder ports. Clean out bird baths on a daily basis, and refill with fresh water.
If a large number of sick birds congregate, consider reducing the amount you feed for up to a month to help reduce close contact between the sick and healthy birds.
If you keep domestic birds, you should prevent contact between captive and wild birds as much as possible. Wash and disinfect your hands thoroughly after handling wild bird feeders or equipment, and reduce the exposure of your birds to biting insects where feasible.
How you can help
Whilst a range of species are known to be susceptible to the avian poxvirus, the cases of infection in tits are not typical of the type of avian pox we are used to seeing, because the lesions are particularly large. It is possible that they are caused by a new strain of avian pox. The early reports were strongly concentrated in south-east England, but there are now indications that the outbreaks are spreading west and north.
We are investigating the spread and intensity of avian pox in the UK, and the full range of species affected by it. If you see any garden bird with growths, please report this to us.
You can access a recording form by clicking on the link on the right. If you have any photographs of the affected birds, it would be helpful if you could attach these to the report, as they will help us identify what may be causing the growths. Your contribution will be valuable for our monitoring work.
If you require further information or advice, please e-mail our Wildlife Enquiries team at wildlife@rspb.org.uk or call 01767 693690 (Monday to Friday 9 am to 5 pm).
Garden Bird Health Initiative
The Garden Bird Health initiative (GBHi) was set up as a UFAW (Universities Federation for Animal Welfare) Working Group in 2003, including among others the RSPB, the BTO, and the Institute of Zoology.
In 2005, the GBHi was extended to become a major research and surveillance project studying garden bird health and disease outbreaks. This unique combination of scientists, conservationists and wildlife vets has proved to be a very successful partnership.
The group develops and publishes guidelines about how to best feed garden birds in order to maximise the benefits for their welfare and conservation, and minimise the risks from infections. It also researches the impacts of disease outbreaks on bird populations.
Last modified: 27 February 2011