Birds that prefer to feed at bird feeders are a potent vector for avian diseases. According to a new study at Virginia Tech, bird feeder visitors are more susceptible to disease and more likely to spread an infection.
The study's conclusions, detailed in the journal Proceedings of the Royal Society B, are the result of weeks spent observing the behaviors and monitoring the movements of several wild flocks of house finches.
Tiny barcoded chips helped scientists identify and track the birds' movements and interactions, while field observations allowed researchers to monitor the spread of a common eye disease called Mycoplasmal conjunctivitis, similar to "pink eye" in humans.
Previous studies hypothesized the most sociable birds, the ones with the most friends, were the most significant vectors of disease. But the latest analysis suggests birds who tend to feed at bird feeders are more likely to contract and spread disease.
The disease can cause house finches, a common backyard songbird, to develop red, swollen eyes that can lead to blindness and result in premature death.
"Our results suggest that in this species, a few individuals -- those that like eating at feeders -- are likely very important in driving disease epidemics," lead study author Dana Hawley, an associate professor of biological sciences at Virginia Tech, said in a press release. "If this is true for other wildlife species as well, we may be able to more effectively reduce disease by targeting these 'high risk' individuals."
Researchers say the new evidence isn't reason to stop feeding birds -- bird feeders help birds survive the hardships of winter. Hawley suggests cleaning and disinfecting a feeder each time they are refilled.
Ultimately, feeders could become a strategic place to introduce antibiotics or other disease-slowing remedies.
"Understanding which animals become sick, and which individuals are most likely to spread disease, can be critical to conservation," said study co-author James Adelman, a former postdoctoral researcher at Virginia Tech, now teaching Iowa State University.