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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 used black plastic to line the rock waterfall that aerates the pond. One day, among the goldfish I had rescued from the bait shop, I discovered an eastern garter snake. Not only do snakes love to hang out in rock gardens looking for insects, but they also like to lie under black plastic liners that absorb the sun's rays and allow them to warm up quickly.

Personally, I like snakes and would rather have them in my yard than the mice and crickets they eat. But people who are not enamored of reptiles should forgo building rock gardens, stacking firewood or placing black plastic near their homes.

Feeding dogs and cats outdoors is another way people start food chains. Bill Heatherly, a former urban wildlife specialist in Kansas City, received a call from a couple who regularly fed their pets in the backyard. Before long, a raccoon family moved into the couple's attic to be close to the steady supply of food.

Another Kansas City resident fed her cat indoors, but allowed the feline access to the house through a pet door, said Heatherly, who is now a wildlife programs supervisor. The woman wondered why her cat was suddenly eating more food and splashing water all over the floor. It remained a mystery until early one morning when the woman confronted a raccoon in the hallway of her home.

A single raccoon can be a nuisance, but imagine the man in Kansas City who started out with one raccoon eating his dog's food. It wasn't long before the food attracted more and more raccoons until 30 were scratching on his door demanding food each evening. The man and his small dog were afraid to go outside, and he was afraid to quit feeding them. Wendy Sangster, a wildlife damage biologist in Kansas City, suggested that the man move the food away from the house a little at a time until the raccoons stopped coming to his deck. Eventually, the man was able to stop feeding the horde altogether.

Not all stories turn out as well. At the Lake of the Ozarks, a man was intentionally feeding a pair of foxes from his back porch, said Jim Braithwait, a wildlife damage biologist in the southern part of the state. After the foxes had a litter of kits, the man fed them, too. As they grew older, the kits, which were not afraid of people, began chasing children and fighting with dogs in the neighborhood. Braithwait asked the man to stop feeding the foxes so they would stop associating people with food. When the man refused to cooperate, the foxes had to be trapped.

Whether fed intentionally or not, crows, starlings, opossums, skunks, foxes, coyotes, bears and other animals are attracted by pet food.

"Commercial dog food is so high in protein and other nutrients that much of it passes through the animal's system undigested," Heatherly said.

Rats stay well nourished by eating dog feces in urban areas where people don't regularly pick up after their pets. If rats are well fed, predators move in to eat them. Red foxes and coyotes are two species that do well in urban areas by preying on rodents, carrion, squirrels and, occasionally, pets.

In West St. Louis County, coyotes are attracted to subdivisions surrounded by green space. Many people admire picturesque backyards with no fencing, so they use underground electronic fences to contain their pets. For coyotes, these fences present no barrier and make it easy for them to occasionally prey on cats and small dogs.

"Coyotes clean up a lot of rodents and carrion," Damron said. "There are many benefits to having coyotes around and, besides, they are here to stay. If we have the habitat, we will have predators. We need to learn to live with them, but not to attract them too close to homes."

In addition to removing food sources, Damron recommends making noise to scare coyotes away when they get too close to houses. "If coyotes aren't challenged, they won't run away from people and may become so bold that they have to be removed," he said.

Sometimes it's hard to know when you are adding an element to a wild animal's food chain. Cities that require people to use plastic trash bags for curbside garbage pickup provide a feast for many animals and birds, especially crows that are adept at breaking open packages. This may help explain why some crows peck holes in black leather car tops in the St. Louis area. A vendor at a suburban St. Louis golf course had no idea that his outdoor concession stand would become part of the urban wildlife food chain when an enterprising crow discovered it could open potato chip bags.

Most people expect to deal with nuisance animals when they plant vegetable gardens. Tender, young plants, as well as their fruits, attract raccoons, squirrels, rabbits, skunks and groundhogs. Simple fencing will keep out most animals. Avoid planting sweet corn unless you are willing to share with raccoons, and don't grow nut trees unless you are prepared for an abundance of squirrels and other rodents.

Plants that are not normally thought of as food also may become a link in a food chain. Scott McWilliams, a wildlife damage biologist, told me about a man in a small community south of Joplin who landscaped his well-manicured yard with roses he planned to enter in a flower show. He called the Conservation Department after the deer found the roses to be tasty. McWilliams' solution was a wooden fence, which saved the roses but changed the owner's landscaping plans.

Conservation Department Ombudsman Ken Drenon hears from lots of people in Kansas City, St. Louis and Springfield who have discovered that their new landscaping projects attract deer. Flower bulbs, hostas, clematis and willows are some of the more popular snacks. Drenon offers another solution to prevent deer damage--planting vegetation that deer don't like to eat. Some examples of native plants reported to be deer-resistant are purple coneflowers, butterfly milkweed, wild ginger, wild geranium, American holly and most varieties of ferns.

The Conservation Department's Grow Native! program can help you attract birds and animals to your yard by providing a natural supply of native foods and habitats through the use of native plants.

Conservation Department animal nuisance complaint specialists suggest that people avoid trying to attract as much wildlife as they can. Provide water, food and shelter only for a limited number of animals. Too many animals can become a nuisance for a neighborhood, cause substantial property damage and spread diseases among wildlife.

For most people, it's a thrill to observe wildlife close to home. Just be sure you are prepared for the extra company. Try to anticipate how your activities might set up a wildlife food chain, or you, your neighbors and wildlife will pay the consequences.

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