“Salmonella infection is a common cause of mortality of wild birds at bird feeders and affects many bird species nationwide,” said Jasmine Batten, a microbiologist with the Department of Natural Resources Wildlife Health Team. “Most outbreaks in wild birds occur during the winter when they are nutritionally stressed and concentrated around bird feeders.”
Salmonella bacteria (Salmonella typhimurium) live in the intestine and are shed in feces of infected birds. Birds contract salmonellosis through direct contact with infected birds or through ingestion of food or water contaminated with infectious feces, according to wildlife experts.
While all avian species can be susceptible to salmonellosis, house sparrows, common redpolls, American goldfinch, and pine siskins are among the most susceptible species and most commonly affected species at Wisconsin bird feeders.
“In years when redpolls and siskins are heavily using Wisconsin bird feeders late in the winter because food sources are scarce farther north, it is not uncommon to get outbreaks of salmonellosis,” explains Batten. “These species might be particularly susceptible because they are nutritionally compromised, or perhaps because they are coming into contact with a strain of Salmonella they don’t usually encounter.”
Public Health Significance
Salmonellosis is a public health concern because all strains of Salmonella are potentially pathogenic to humans and animals. However, it appears that wild birds mainly acquire the disease from the environment and that infected wild birds play a relatively small role in the transmission of disease to domestic animals and humans.
While dogs and cats are rarely infected, pets should be discouraged from consuming bird carcasses to reduce risk of contracting salmonellosis. If you must handle a dead bird wear disposable gloves or plastic bags over your hands. Wash your hands thoroughly after the clean up is completed.
What you can do to reduce the risk of salmonellosis in your backyard.
- Clean feeders, feeding areas and birdbaths regularly using a 10 percent bleach solution as a disinfectant before a final rinse.
- Clean up seed hulls under bird feeders.
- Consider moving bird feeders periodically to prevent buildup of waste underneath the feeder.
- Consider adding additional bird feeders to reduce crowding.
- Keep seeds and food dry.
- Change water in bird bath regularly.
- Wear disposable gloves when cleaning a bird feeder or birdbath.
- If you observe dead or sick birds near a feeder, take it down, discard all seed, and thoroughly clean the feeder. Wait at least a week before setting up the feeder again.