Feeding wild birds helps fuel them and provides viewing pleasure, yet a communal feeder may hold hidden risks, reports a recent study in Ecology Letters.

In reviewing 20 published research papers on host/pathogen interactions in human-fed wild populations, researchers at the University of Georgia’s Odum School of Ecology, in Athens, found that intentional feeding changed their behavior and diet enough to foster potentially harmful growth of parasites and viruses.

“Feeders can bring unexpected species and more birds together more frequently than normal, facilitating conditions for parasites and other contaminates,” says lead researcher Daniel Becker. Birds crowding into tight spaces to reach tasty morsels also makes it easier for pathogens like house finch eye disease and respiratory ailments to be passed among them.

Maintain cleanliness. Stephen Kress, director of the National Audubon Society’s Project Puffin, advises that safe bird feeding includes completely scrubbing out feeders with a 10 percent non-chlorinated bleach solution at least a few times a year, and certainly between seasons.

Be food-specific. While using bird seed mixtures to attract a wide range of species is cheaper, such food usually includes fillers like milo that most birds quickly pass through, making a mess under the feeder that can make birds sick. Kress suggests, “Buy specific seeds for specific feeders—like cracked corn and millet in one and only sunflowers in another. This decreases interactions between species that eat the different seeds and dramatically cuts waste.”

Creative option. Try some peanut butter and other healthful ingredients, suggests Julie Craves, supervisor of avian research at the Rogue River Bird Observatory at the University of Michigan-Dearborn, in a recent edition of BirdWatching magazine. “It’s high in fat, protein and calories.” Avoid nut butter made with the artificial sweetener xylitol, as it can kill birds.

She recommends mixing one part organic peanut butter with four or five parts plain, non-GMO (genetically modified) cornmeal and add oats and raisins. Plain or chunky works. “The dough can then be shaped into portions that will fit in suet feeders or logs, or just placed in feeding trays.”

This article appears in the January 2017 issue of Natural Awakenings.