Bird feeder study
Do backyard feeders help — or possibly hurt — birds like this northern cardinal? A new study of nesting success says the answer is complicated. (Photo: iStock.) |
Backyard bird lovers may want to take note: Putting out feeders full of seed may also attract predators that eat eggs and nestlings. But the feeders may also help satiate predators so they’re less likely to target nests.
In a new study published in The Condor: Ornithological Applications, scientists from The Ohio State University and Cornell University investigated the consequences of supplemental bird food on predator-prey relationships.
Jennifer Malpass |
Robins and cardinals are commonly found in mid- and understory vegetation in residential neighborhoods, where food is often supplemented via bird feeders.
Malpass was a researcher with Ohio State’s School of Environment and Natural Resources (SENR) at the time of the study. She’s now a wildlife biologist in the Bird Banding Laboratory at the U.S. Geological Survey’s Patuxent Wildlife Research Center in Maryland.
Co-authors on the study were Amanda Rodewald, director of the Cornell Lab of Ornithology and a professor in Cornell’s Department of Natural Resources, and Stephen Matthews, assistant professor of wildlife landscape ecology with SENR. SENR is part of Ohio State’s College of Food, Agricultural, and Environmental Sciences.
Complex relationships, species-specific responses
The scientists found that relationships among feeders, predators and nest survival were complex: Neighborhoods with lots of feeders had more cowbirds and crows — birds known to prey on songbird nests — but that generally didn’t affect the success of the nests the researchers monitored.
“One key message of our work is that there may be species-specific responses to anthropogenic (human-provided) foods,” Malpass said.
American robin nest showing signs of predation (Photo: Jennifer Malpass) |
A complementary study by the same team identified crows as the most common nest predator of robins, responsible for 53 percent of nest predations documented with video cameras.
Human-dominated environments, where bird food supplementation is common, are complicated, variable and don’t lend themselves to simple generalizations, Malpass said.
“Given the popularity of backyard bird feeding, this is a pertinent area for additional research,” she said.
Partnerships with homeowners important
Engagement of property owners was a key ingredient in conducting the study, the scientists said. They worked with more than 200 homeowners to monitor nests and survey predators in their yards.
“One of the challenges of conducting research in the suburban matrix is gaining access to private property,” Malpass said.
“In our experience, most of the residents in our focal neighborhoods were willing to allow access to their yards and had a positive experience being part of the project.”
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