Diseases seen in birds

Because garden birdwatchers take so much interest in the birds visiting their gardens, they may occasionally come across diseased birds. A number of different diseases have been reported in birds seen at garden feeding stations: 

• Avian pox, a disease which causes warty or tumour-like growths, particularly on the head, wings or legs.
• Colibacillosis, a disease caused by Escherichia coli (E. coli). Birds look weak, lethargic and fluffed up, and may have digestive problems.
• Salmonellosis, a disease caused by Salmonella bacteria. Birds look weak, lethargic and fluffed up, and may have digestive problems.
• Trichomonosis, a disease caused by the parasite Trichomonas gallinae. Birds may show difficulty in swallowing, laboured breathing, and swelling of the throat and neck.
• Growths on the legs, feet or beak, which may appear as crusty scales or warts and are usually caused by mites or viruses.

Anecdotal evidence suggests that some bird species may be more susceptible to disease than others. Certainly, Greenfinches, Chaffinches, Siskins, House Sparrows and Collared Doves appear to be the most commonly reported victims of diseases. This may, in part, reflect the gregarious nature of these birds and their tendency to feed in flocks; the transmission of disease between individuals tends to be increased where birds gather together in large numbers. 

Avian influenza

Avian influenza is a disease caused by an influenza virus. Birds may have a swollen head, watery droppings and show neurological symptoms.

Since the winter of 2021/22, avian influenza has spread through many bird species, including wildfowl (ducks, geese and swans), seabirds and birds of prey. It has caused high levels of mortality. 

If you find a dead wild bird, or see a suspected case of avian influenza, you can report it and assist in our research into the outbreak. Find out how to report dead birds. 

What you can do

• A few simple precautions will help limit the spread of disease in gardens and on feeders. Learn more about good garden feeding hygiene.
• Help us understand disease in wildlife by reporting any cases that you see. Information on diseases and other forms of mortality in garden wildlife is being collected through Garden Wildlife Health.
• If you find a dead wild bird, or see a suspected case of avian influenza, you can report it and assist in our research into the outbreak. Find out how to report dead birds.