Wild Chaffinch Population and Trichomonosis

The chaffinch is one of Britain's most common birds, but a devastating disease - trichomonosis - has caused significant population declines in recent years and raises important welfare concerns.

Key Facts

Chaffinches were once the UK's most common breeding bird with approximately 6 million pairs
Trichomonosis, a protozoan parasite infection, caused approximately 35-40% population declines in greenfinches and affected chaffinches from 2005
Affected birds develop lesions in the mouth and throat that prevent swallowing, causing slow starvation
The disease is transmitted through shared feeding and drinking at bird tables
UK chaffinch populations declined by approximately 28% between 2010 and 2020

Welfare Considerations

Trichomonosis causes a prolonged and distressing death through progressive inability to swallow. Birds with the infection visibly struggle to eat, show lethargy, and often remain on the ground where they are vulnerable to predation. Garden bird feeders act as disease transmission hubs - birds sharing contaminated food and water spread the parasite. Regular cleaning of feeders and fresh water provision significantly reduces disease transmission. Finding affected birds requires prompt reporting to wildlife agencies.

What You Can Do

Clean bird feeders and bird baths regularly - at least weekly - with dilute bleach solution
Use multiple small feeders rather than one large feeder to reduce crowding
Report birds showing signs of trichomonosis to the Garden Wildlife Health project
Remove fallen food from the ground daily to reduce disease transmission risk