Wild Bird Supplementary Feeding and Disease

Supplementary feeding of wild birds creates disease transmission risks that can cause mass mortality events, making hygiene management a critical component of responsible bird feeding.

Key Facts

Trichomonosis (caused by Trichomonas gallinae) has caused major greenfinch and chaffinch population declines
The disease is spread via contaminated food and water at feeding stations
Salmonellosis outbreaks at feeding stations cause mortality in house sparrows and other species
Weekly cleaning of feeders and bird baths with 5% disinfectant eliminates most disease risk
Removing feeders for two-week periods during outbreak events reduces transmission
Ground feeding stations are particularly high-risk as they concentrate birds and prevent separation by species

Welfare Considerations

Supplementary bird feeding, when poorly managed, creates disease amplification opportunities that can cause more harm than the feeding provides benefit. The mass mortality of greenfinches from trichomonosis is directly linked to contaminated feeding stations. The solution is not to stop feeding but to maintain rigorous hygiene - weekly disinfection of feeders and water sources, removal of uneaten food, and temporary suspension of feeding during local disease events. Responsible feeding practices are described in detail by the RSPB and BTO with evidence-based guidance.

What You Can Do

Clean bird feeders and water sources weekly with hot water and 5% disinfectant solution
Remove all uneaten food daily to prevent accumulation that harbours pathogens
Stop feeding temporarily if sick birds are observed at your station and clean thoroughly before resuming
Report unusual bird deaths to the Garden Wildlife Health project for disease surveillance