But pesticide-use hit falcons hard. Studies have shown that the pesticide DDT affected the thickness of falcons' eggs, resulting in dwindling populations. In 1970 the peregrine falcon, the world's fastest bird, was placed on the endangered species list with only 39 known mating pairs in the western United States.
With the ban on DDT and the help of programs like the Peregrine Fund, conservationists began rebuilding the peregrine population. In 1999 peregrines were removed from the Endangered Species List.
Better Conditions Boost Bird Numbers
The same successes that have helped restore falcons like the peregrine have also helped boost their prey numbers, causing a problem for airplanes.
Certain bird populations are soaring exponentially throughout the U.S., especially for waterfowl (geese and ducks). Commercial aviation has also increased over the years, so there are more flights encountering more birds. And airports with their big green fields and adjacent rural areas often make a most attractive habitat for birds to hang out.
"The reason the problem has increased is that we've seen a tremendous increase in populations of bird species that are hazardous to aviation," said Richard Dolbeer, a wildlife biologist with the U.S. Department of Agriculture who helped found the Bird Strike Committee USA in 1991. Interest in this problem has grown, he said, with more than 400 people attending the group's annual meeting last October.
One of these booming bird species is the double-crested cormorant. In 1972 this species had only had 89 nests on the Great Lakes. Now there are 115,000.
Dolbeer said an increasing awareness of problems like pesticides, as well as the development of wildlife refuges, has helped these bird populations enormously.
"It's great," he said. "We've really been successful beyond our wildest dreams in restoring these populations." But while bird recovery may be a success story, people now need to learn how to manage the flocks, he said.
Along with increasing populations, many birds and other wildlife are feeling quite at home in urban settings. "They feel very comfortable going to airports to feed and rest," Dolbeer said.
Technology has also upped the stakes for wildlife. Modern jets have fewer and quieter engines than the roaring aircraft of the past, so wildlife may not be as easily startled or even aware of their presence.
Most airports use pyrotechnics and propane cannons to keep flocks away, as well as keeping the airport grounds less attractive for animal inhabitants by mowing tall grasses and covering ponds.
Falconry is another tool to prevent permanent residents, Dolbeer said. "It has a lot of sex appeal," he said. "It just sounds so cool."
At JFK, Adam said, during peak summer hours up to five falconers may be working with their charges 17 hours each day. Adam's company also uses recorded bird distress calls, pyrotechnics, and propane cannons to control problem birds.
While falconry can be an effective tool, Dolbeer said, it can't be used in every situation. The falcons and their falconers can't work in high winds or temperature extremes. And many airports have chosen alternative methods because of falconry's higher cost.
Each airport has its own problem species. John F. Kennedy Airport, situated on Jamaica Bay, is the stomping ground for gulls and migratory birds. Inland airports are havens for other species like Canada geese and red-tailed hawks. And the problems aren't all airborne. Coyotes, white-tailed deer, elk, and even alligators can cause problems on the ground.
As a result, wildlife management has to be tailored to each airport's needs. "Wildlife control at airports is part science and part artand there's more than one way to do it," said Dolbeer.
The important thing, Dolbeer said, is to keep working at it. "It's like mowing the grassit's something you have to continually work on."
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From the National Geographic Store:
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Additional Information from Related Web Sites:
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