The call of the peregrine falcon is unmistakable, though difficult to describe.
Shrill squawks emerged from the top of a 20-foot-tall platform suspended over Centennial Marsh west of Fairfield Monday afternoon as four 35-day-old female peregrine falcons were moved to a small wooden box, called a hack box, where they would become accustomed to the outdoors over the ensuing 10 days.
Then, the bars on one side of the box will be removed, and the young birds will be able to come and go as they please. Before fall, and in as few as two weeks, they'll be gone.
"The word peregrine means 'wanderer' so they could go pretty much anywhere," said Idaho Department of Fish and Game Regional Non-Game Biologist Bruce Haak, who handled the birds Monday.
The young peregrines' calls cut through the muffled mid-day wind, and squid-like cirrus clouds marched across the Camas Prairie. The four birds will bring the total number of peregrines released in Centennial Marsh to 21.
The release of the four young birds was part of an ongoing program to reintroduce peregrine falcons to the wild. The species was a ward of the Endangered Species Act for 26 years, from passage of the ESA in 1973 through 1999. The successful reintroduction of peregrine falcons to the wild is considered one of the most successful reintroduction programs in history.
In part to celebrate that success, and to honor the state's roll as a sanctuary for birds of prey of all stripes, Idaho will release its commemorative quarter late this summer or early this fall. It will feature the peregrine falcon.
"The peregrine became the state raptor two years ago," said Susan Whaley, the public relations coordinator for Boise-based The Peregrine Fund. "The World Center for Bids of Prey is in Boise, and the fact that we were central to the recovery of the birds of prey is one of the reasons it's on the state quarter."
Rivaled only by the osprey, the peregrine falcon has one of the most global distributions of any bird of prey. This falcon is found on every continent except Antarctica, and lives in a wide variety of habitats from tropics, deserts, and maritime to the tundra and from sea level to 12,000 feet. Peregrines are highly migratory in the northern part of their range.
There are three subspecies in North America: peales, which is a coastal species; arctic, which is the largest in population; and anatum, which is the inland species endemic to Idaho and the only North American subspecies listed as endangered.
In the early 1970s, there were fewer than 40 known breeding pairs of anatum peregrine falcons in the United States and none east of the Mississippi River. Thanks to reintroduction efforts like Monday's, there are now more than 15,000 birds nationwide. There are about 36 breeding pairs in Idaho.
It was due to pesticides like DDT that populations plummeted. The chemicals caused the female to lay thin-shelled eggs that were easily broken, killing developing embryos. After banning of DDT in the United States in 1972, The Peregrine Fund released more than 4,000 captive-reared birds in 28 states over a 25-year period.
This fierce predator of smaller birds, especially sandpipers, plovers and ducks, is renowned for its 200 mph dives, or stoops, when it attacks, hits, and knocks its prey out of the sky. Peregrine falcon habitat is on steep cliff faces where they are protected from predators and can easily make prey of other birds. Because of that, the birds have adapted well to living in cities, where tall buildings, water sources, easy prey and few natural predators assist their survival. In fact, part of the successful reintroduction of peregrine falcons to the wild is the release of birds in urban areas. The idea is that they will eventually migrate elsewhere.
When peregrine populations plummeted, great horned owls and golden eagles took over their habitat, Haak said. Therefore, the biggest challenge to reintroducing them to their native range was figuring out how to return them without adults around for protection.
"The environment had changed," Haak said.
After developing successful captive rearing programs, the next step for The Peregrine Fund was to release the young birds into the wild. To do this, the organization relied on techniques developed by the falconry profession: a method called hacking, whereby juvenile birds are released without any care or feeding by parent birds.
Poles or towers are erected with a platform atop. A hack box—a large wooden crate with a barred front—sits on the platform. Once juvenile peregrines are large enough to tear apart their own food they are placed in the box.
In Centennial Marsh, Fish and Game Habitat Biologist and Centennial Marsh Manager Terry Gregory then watches over the birds and feeds them freshly killed quail.
According to Gregory, only two of 21 birds released in Centennial Marsh have died at the site. But first-year mortality is high, estimated at 75 percent.
While they're still on site, Gregory tracks the birds with radio telemetry equipment.
"Last year they left the last week of August, and we don't know where they went," he said. "The telemetry equipment only goes so far, about 10 miles line of sight."
Initial efforts to hack peregrines on their traditional wild cliff sites were stymied by heavy nocturnal predation by great horned owls. Therefore, hacking moved into open areas in wetlands, islands and estuaries along coasts and bays where owl attacks would be minimal.
"Yep. There's a little bit of art, and a lot of science to this," said Rich Howard, president of Boise-based Biosage Consultants and a volunteer during Monday's release.
For Haak it was another step in the right direction in an effort he has been part of since it's inception.
"I actually got into science because I was into falcons," the Virginia native said. "Of course peregrine falcons have been a prominent issue the entire time I've been alive. This is very exciting for me."
Idaho Department of Fish and Game Non-Game Biologist Bruce Haak moves a 35-day-old peregrine falcon to a hack box on the Camas Prairie Monday. Photo by Willy Cook
