Urban Food Chains

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Published on: May. 2, 2003

Last revision: Nov. 15, 2010

My neighbor in Columbia used to toss seeds onto her driveway every morning for a flock of pigeons. Soon afterwards, a red-tailed hawk took up residence in a large cottonwood tree with a clear view of the driveway.

Slowly but steadily, the number of pigeons dwindled, to the delight of some homeowners who didn't want the birds roosting and defecating on their houses. After the supply of pigeons disappeared, however, the hawk remained. It fed on a variety of songbirds that were attracted to bird feeders.

When it started killing songbirds, some of the neighbors weren't as happy about the hawk.

"When people in cities complain about predators hanging around their homes, my first question is: Do you feed birds? Most say, ‘Yes,'" said Daryl Damron, a wildlife damage biologist in northern Missouri. "Anytime you set out food for birds, you start a food chain that often extends far beyond the birds you had in mind."

Bird feeders bring in songbirds, but they also attract mice and other rodents, including squirrels. In turn, these prey animals attract more predators, such as house cats, red foxes and coyotes. In some cases, bird feeders can become the equivalent of a predator feeding station.

Feeding birds in winter and early spring can help them survive when food sources are scarce, Damron said, but in the late spring and summer, when birds of prey and other predators are feeding young, birds at feeders are hit hard.

People often create sources of food for animals without realizing it. Yard and streetlights that remain on all night attract a variety of wildlife. While walking my dog on a winter evening in a Kansas City suburb, I watched an owl swoop down from its perch on a streetlight to catch a mouse eating seeds that had fallen from a feeder. Lights also attract insects, which then bring in bats, frogs, toads and other predators that eat them.

Water gardens, a popular addition to many city and suburban backyards, provide a year-round source of water, and another place where predators can find a meal. Sometimes your pets become prey. For example, people who purchase expensive Koi fish for their water gardens often train the fish to come to the surface for food. This works to the advantage of raccoons that find easy pickings in the shallow water. The Conservation Department's urban wildlife biologists also receive complaints of herons snacking on pet fish.

In my water garden, I

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