Salmonella spp. bacteria cause gastroenteritis—inflammation of the intestine—in animals, including humans and birds. These bacteria are carried normally by some birds, and can survive for long periods in soil and water. Ingested in water or food, salmonella bacteria cause abdominal distress with diarrhea, and sometimes spread to the blood and internal organs.
Salmonella infection usually strikes birds when they are stressed: when food is scarce, in extreme weather, when the weather is very hot, very cold, or even cool and wet. Spread through droppings, the salmonella bacterium passes easily among songbirds congregating at birdfeeders, and among flocks of water birds.
Birds infected with salmonella tend to huddle and may appear surprisingly tame. These sick birds shiver, appear unsteady, have drooping heads and wings, suffer from lack of appetite, and lose weight. They may appear excessively thirsty or they may not drink at all. Their droppings are yellowish or greenish and possibly bloody. Death is common.
There’s always a danger of diseases spreading when birds congregate, but you can minimize the risks for your backyard birds. Start with a good birdfeeder—one that’s:
You can also bake birdseed for one hour at 250F to kill contaminating organisms, though this will not necessarily destroy all harmful toxins produced by bacteria or molds.
Cleaning and disinfecting your birdfeeder
Even when the bird population is healthy, birdfeeders should be cleaned and disinfected every other week to minimize the chances of mold growth in the seed or contamination with harmful organisms:
DON’Ts for successful bird feeding:
Bird baths can spread the salmonella bacterium and other diseases too. Refresh the water in your bird bath several times each week and clean the bath with 10 percent bleach every couple of weeks, just as you do your birdfeeder.
Birds and Trichomonas gallinae
Lavoie, Judith. “There's deadly bacteria lurking in your bird feeder.” Vancouver Sun,Sunday, June 03, 2007
Washington Department of Fish and Wildlife. “Bird feeding precautions urged to stem bird disease.”