Colibacillosis is caused by the bacterium Escherichia coli (more familiarly known as E.coli), with most incidents in garden birds associated with the strain O86. 

Affected birds show general symptoms of ill health (such as fluffed-up plumage and lethargy) that are similar to those caused by other diseases, including salmonellosis. The timing of colibacillosis outbreaks within the UK appears to be slightly different from the pattern seen in Salmonella (which mainly occurs during the winter months); in a recent Scottish study, most cases of colibacillosis occurred in the months March to May.

Pathology and disease spread

Affected individuals appear fluffed-up, weak and lethargic. E.coli does not damage the internal organs in as visible a manner as Salmonella but the toxins that it produces may prevent the digestive system from working correctly.

Although human illness from E.coli O86 is uncommon in the UK, there is the potential for spread to humans. As such, it is essential that sensible hygiene precautions are taken when cleaning feeding areas used by birds or removing and disposing of carcases.

Species affected

Colibacillosis is known from a wide range of species, with reports more common for social species like House Sparrow and Greenfinch.

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.