Bright Lights Bird City
In metropolises throughout the country, birds of prey are increasingly becoming part of the landscape
- Cynthia Berger
- Apr 01, 2001
James Baggett is the editor of a gardening magazine, but on a brisk afternoon last spring, his mind was not on plants. "Wow!" he said. "A red-tailed hawk just flew right by my window."
The stout hawk with the rusty-red tail is common in North America, so usually a red-tail sighting barely boosts a bird-watcher's heartbeat. But this sighting was something special: Baggett's window is 12 stories up a Manhattan skyscraper, where the bird he's most likely to see is a pigeon, not a predatory bird with a four-foot wingspread.
Birds of prey, or raptors, aren't unknown in New York City or other urban areas, of course. Peregrine falcons, for example, inhabit the Big Apple, Chicago, San Francisco and other U.S. cities. Rescued from near extinction by a captive-breeding program and recently removed from the U.S. Endangered Species List, the peregrine owes its recovery in part to its ability to adapt to city life. And this is just one of several types of large predatory birds to flock downtown in recent years. Merlins, the peregrine's smaller cousins, now stalk sparrows on the streets of Saskatoon, Canada. Cooper's hawks hang out in courtyards in Tucson. And those New York red-tails enjoy the ultimate measure of urban success: Nesting on Mary Tyler Moore's apartment building and perching on Woody Allen's balcony, they are the subject of the best-selling book Red-Tails in Love.
"There's no doubt in my mind: Not only have more species of raptors adapted to life in cities, but raptor numbers seem to be increasing," says McGill University researcher David Bird, coeditor of the book Raptors in Human Landscapes. He estimates that at least a dozen different North American raptors are now spotted routinely in cities.
And where the big birds go, scientists follow. In the past, being a bird ecologist often meant working in pristine places. "Now there are a lot of people going full steam, studying birds in urban areas," says John Marzluff, a researcher at the University of Washington. "We're seeing more advanced investigations of how birds adapt to life in an urban environment, the evolutionary reasons for change in an urban area. And researchers are also looking at the conservation implications for urban bird populations."
Before scientists could begin these studies, however, they had to shake off some old assumptions. Consider the case of the Mississippi kite. Not long ago, the scientific literature said these birds nested exclusively in woodlands along prairie rivers. Actually, the small, gray raptor with the startling bloodred eyes is now a common sight in such sizable cities as Wichita, Kansas, and Oklahoma City.
"Well, sure, kites used to nest along rivers," says Jim Parker. "On the prairie, that's where the trees were!"
Parker, a Maine-based wildlife rehabilitator and educator who studied kites for his doctoral research at the University of Kansas, credits people with helping create habitat for Mississippi kites. In particular, he says, the Civilian Conservation Corps (CCC) planted large numbers of trees in prairie states in the 1930s. "The trees planted by the CCC matured in the 1970s, and that's when I really saw the kites start moving into urban areas," he says. Golf courses, too, are excellent habitat for kites, and Parker has also spotted the birds nesting in suburban backyards, near a city courthouse and even on a traffic island.
Another raptor that hasn't read the scientific literature about its habitat preferences is the Cooper's hawk. This crow-sized, long-tailed hawk was once thought to require expanses of pristine woodland. But recent research indicates that Cooper's hawks in developed areas can fare better than those in natural environments. Robert Rosenfield, who studies the raptor at the University of Wisconsin, has found that hawks in Stevens Point, Wisconsin (population 25,000), are not only willing to nest closer together than their forest counterparts, but they produce more offspring. One reason may be the many starlings, robins and chipmunks in neighborhoods, which serve as Cooper's hawk convenience food.
Jim Parker sees the same thing in his urban kites: They nest closer together and fledge more offspring than kites in "natural" habitats. And Fred Gehlbach of Baylor University, a pioneer in comparing urban and rural raptors, has drawn the same conclusions for eastern screech owls around Waco, Texas.
What draws raptors downtown? Bill Mannan of the University of Arizona and his former graduate student Clint Boal, now with the Minnesota Cooperative Fish and Wildlife Unit, have examined this question for Cooper's hawks in Tucson. "Obviously, the desert Southwest is a dry environment," says Boal, "so the city is attractive because birds can find water," in the form of birdbaths, swimming pools and lawn irrigation systems. The hawks also find fine dining, in the form of mourning doves and Inca doves, which are more abundant in the city than in the surrounding desert. Most important, they find trees--including many tall, exotic species planted by city officials during the past 50 years.
Trees also have helped lure merlins into Saskatoon, a city of 200,000 in Saskatchewan, Canada. At the turn of the century, this prairie city was essentially treeless. Settlers planted ornamental spruces, which attracted another urban immigrant: the American crow. "Crows are really what created habitat for merlins," says Lynn Oliphant of the University of Saskatchewan. "Instead of building their own nests, merlins use empty crow or magpie nests. So even though the trees were mature by the middle of the century, merlins didn't really start nesting here till after the crows arrived in the late sixties and early seventies." And the raptors persist thanks to another nonnative species: the house sparrow, introduced from Europe and now a major part of the urban merlin's daily diet.
Besides abundant prey, other factors help make city life appealing to raptors. Oliphant says, "The city climate is probably a bit warmer than in outlying areas. And the city environment may offer some protection from predators." This is probably why Mississippi kites do well in all urban areas, says Parker. "Sure, you find raccoons in town as well as in the woods, but in town they're busy avoiding people. Same with great horned owls--they'll work a prairie shelterbelt, preying on nesting kites, but they're much less likely to come into town."
And if predators do make it into town, urban raptors may enjoy another kind of protection, says Bill Stout, a high school biology teacher who studies Milwaukee's urban-nesting red-tailed hawks. In Wisconsin these somewhat shy hawks were once thought to use trees exclusively. But Stout has spotted red-tails nesting on billboards, on a fire escape, atop civil defense sirens, on a 250-foot-tall cellular phone tower and even on the outfield lights of Milwaukee's baseball park. Such nest sites probably offer more protection than a traditional tree, Stout says. "A raccoon can't climb a steel structure so easily. And by nesting so high, hawks may get protection from great horned owls, which prefer to fly low and avoid open areas."
Urban-nesting raptors also avoid persecution from another predator--the kind that kills with a shotgun. "Here in Texas, hawks used to be regarded as ‘chicken-killing varmints,' so people shot them routinely," Gehlbach says. Today, laws protect migratory birds. In addition, it's illegal to discharge a firearm within most city limits.
One final advantage of city life, adds Bird, is that in most cases, the habitat won't disappear. "Most downtown parks are not going to be demolished anytime soon," he says.
If raptors can thrive in cities, does that mean we don't have to worry about protecting unspoiled habitat? Hardly. For one thing, it's still too early to tell whether urban landscapes truly are good places for birds to live, says Bird. "Are populations actually growing, or does careful study reveal that mortality exceeds the reproductive rate?" he asks. "We just don't yet know whether cities are sources or sinks for raptor populations."
"I think it's great to have a variety of birds in an urban landscape--the more the better," says Oliphant. "But think about this: Right now, less than half of one percent of the total North American merlin population nests in cities. Even if they are doing slightly better than rural birds, that's still a drop in the bucket. The success of raptors in cities shouldn't detract from our efforts to protect natural habitats where birds can maintain their populations."
And urban life does have some drawbacks. Swainson's hawks nesting in Davis, California, for example, fledge fewer young than rural birds. Why the difference between Swainson's and the prolific Cooper's hawks in Stevens Point? "Swainson's are very particular in their feeding habits," says Bird. "They had to go a long way out of town to get the groceries. That made it tough for them to raise their young."
And though Cooper's hawks are doing well in Wisconsin, in Tucson 40 percent of their nestlings succumb to the disease trichomoniasis, which they get from the doves their parents feed them. And many of the remaining birds eventually die in collisions with windows, the major cause of mortality among adult Cooper's hawks in Tucson.
City streets pose other dangers for nesting raptors. If there are fewer predatory owls, there are more dogs and feral cats. And young birds making their first flights must dodge traffic, says Jennifer Coulson, a graduate student at Tulane University. Another hazard for city raptors is the risk of electrocution when they perch on power poles. "Power poles are a problem in rural areas, too," says Coulson, "but in cities you have so many more of them!" Finally, some birds die after eating pigeons that have been poisoned in the name of pest control. That's what killed one of New York's celebrity red-tails a few years ago.
But despite these problems, now that we know some raptors can adapt to urban life, researchers say we need to include developed areas in wildlife management plans. "As we usurp habitat through urban sprawl, it becomes more and more important to understand what will allow wildlife to survive in urban habitat," says Coulson. "We have to ask, are there ways we can develop cities wisely so that we can allow wildlife and humans to coexist?" Adds John Marzluff, "Right now, only three percent of the Earth's surface is urbanized. But projections for the future show that number will certainly increase. I think it's significant that many ecologists are recognizing urbanization as a major threat to wildlife diversity, and they're developing research programs to address that issue."
One example is the National Science Foundation's Long-Term Ecological Research Program, which added urban sites to its roster a few years back. At one of these sites, in Phoenix, researchers are examining how landscape design affects birds. Meanwhile the U.S. Fish and Wildlife Service (FWS), traditionally concerned with wildlife refuges in natural areas, recently launched the Urban Conservation Treaty for Migratory Birds. Under this program, FWS awards grants to cities for protecting migratory bird habitat, or for educating the public about birds.
Public education is important because some people aren't happy to have raptors as neighbors. "Years ago, a woman threatened my life because I was helping bring peregrines into Montreal," says Bird. "She didn't like the idea that peregrines kill the pigeons she feeds." Caged bird owners also get upset if their pets escape and the peregrines pick them off. And building managers don't like to change their window-washing schedules to avoid disturbing nesting birds.
But most people like raptors, says Mannan. "Most homeowners I talk to are delighted to have them around. They're beautiful to watch--and educational for the kids." And despite people's preferences, raptors are continuing to move into cities. Rosenfield, for one, thinks it's great.
"Instead of wondering ‘Will I ever see a Cooper's hawk again?'" he says, "I look out my window and see them regularly. Sure, they're not breeding in forest habitat the way they used to, but think about it--we don't have wilderness in central Wisconsin anymore. So thank goodness we still have those birds."
Pennsylvania writer Cynthia Berger is a frequent contributor to National Wildlife.
NWF Campaign: Nature in Your Neighborhood
Raptors are an increasingly common site in urban and suburban communities. This year's National Wildlife Week campaign, Explore Nature in Your Neighborhood™, focuses on birds and other creatures you can find in your own backyard. NWF encourages you to explore the nature in your neighborhood during the week of April 16-21.
NWF also encourages communities to create suitable habitats for wildlife. The Community Wildlife Habitat™ program is an effort to create entire municipalities where people, flora and fauna can flourish.