Why don't birds get sick from drinking dirty water in birdbaths?
"Why do you think they don't?" said Kevin McGowan, an ornithologist at Cornell University. "I'm sure there is some disease transmission."
Birdbath owners should try to keep the water clean. Some contamination is inevitable, he said. But most birds don't spend much time at a birdbath, so the benefits of hydration outweigh the risks.
Many birds do have powerful protection from infection when it comes to eating rotten and possibly diseased foods. Buzzards and other birds routinely consume carrion, for example. One way they handle the risk is simply to digest pathogens, including viruses and bacteria. It is rare for an organism to be indigestible and pathogenic.
Enzymes in the digestive tracts of birds break down most of what is ingested, and usually disease agents are not consumed in sufficient amounts to lead to infection. A big advantage for birds is the speed of their digestion, which is much faster than that of other vertebrates because of the prodigious need for nutrients to meet their high energy requirements.
ActiveStyle on 05/19/2014