Supplementary feeding of garden birds provides direct welfare benefit through winter food scarcity but requires good hygiene and appropriate food types to avoid causing harm.
Garden bird feeding welfare requires attention to both what is provided and how feeders are maintained. Dirty feeders harbour Salmonella, Trichomonas, and other pathogens that cause disease in birds that cannot control their disease exposure risk. Trichomonosis has devastated greenfinch and chaffinch populations in the UK - birds die from throat lesions that prevent swallowing. Appropriate food types avoid the salt toxicity and gut problems caused by bread, salted nuts, and inappropriate kitchen scraps. Good feeder hygiene - washing with dilute disinfectant fortnightly and moving feeder positions regularly - prevents disease concentration.