Migrating Hawks
JB: This is Earth and Sky. September and October are good months to visit Chelan Ridge in Washington State’s eastern Cascades mountains.
DB: On almost any day, you can see hawks, falcons, and eagles soaring on their annual migrations – some destined as far south as Argentina. Chelan Ridge is ideal for hawk-watching because a forest fire cleared the ridgetop in 1970. About 3,000 hawks and other raptors pass here each year.
JB: Bird scientists don’t know exactly where many western birds of prey migrate to. That’s why the Chelan Ridge hawkwatchers have been banding migrating birds. Researchers lure the birds down to Earth where they’re captured in fine mesh nets and fitted with numbered ankle bands. The bands let scientists track birds that are later recaptured.
DB: But not many bands are recovered – only about one in four or five hundred. Now researchers have a plan for a high-tech banding operation. Some of the largest raptors -goshawks, golden eagles, and red-tailed hawks – are being fitted with “satellite transmitters” that will beam a signal to an orbiting satellite – and let scientists track where exactly where the birds go on their long migrations – almost minute-by-minute.
JB: The end result, it’s hoped, will be protection of those areas for these birds. Special thanks today to the National Fish and Wildlife Foundation, in cooperation with the U.S. Forest Service. We’re Block and Byrd for Earth and Sky.
The following individual(s) were interviewed for today’s show. Our thanks to:
Kent Woodruff
Wildlife Biologist
U.S. Forest Service
Winthrop, Washington
The following articles and websites were used in preparing this script:
Mottram, Bob. “Wrapped up in raptors: Observers find Sawtooth Ridge the ideal lookout to study predatory birds migrating south.” Tacoma News Tribune, Tacoma, Washington, Sept. 25, 2000.
A report on the raptor migration project posted on the Methow Valley home page
The newsletter of the Raptor Research Group, which participates in the Chelan Ridge project
An Associated Press article published in the Sun newspaper of Brementon, Washington, October 9, 2000.
Website of HawkWatch International page describes the research being conducted at Chelan Ridge in the Okanogan National Forest.
Original program synopsis:
“Every year, thousands of birds of prey migrate south along Chelan Ridge in Washington State to wintering areas some as far as Argentina. Biologists here are capturing and fitting some of the birds with tiny satellite transmitters to learn what routes they take, how fast they go, and where they end up with the ultimate goal being the conservation of these animals at the top of the food chain. According to Kent Woodruff, because raptors are at the top of their food chain, they are important indicators of an ecosystem’s health.”
Author’s notes:
Chelan Ridge looms 5,600 feet above 55-mile-long Lake Chelan. It makes an ideal hawkwatch site because a forest fire cleared the ridgetop in 1970, creating a fairly open area where the vegetation is mostly sagebrush and small willows and loadgepole pines. The mix of habitat types attracts many kinds of migratin birds, including warblers, flycatchers, and chickadees, the kinds of birds that many raptors prey on. “It’s a big smorgasbord for the raptors that are migrating through,” says Kent Woodruff, the Forest Service biologist who heads the hawkwatch.
The hawkwatchers at Chelan Ridge have spotted 16 different raptor species in the three years since observations began. The most common migrants passing over head are sharp-shinned and Cooper’s hawks, both forest-dwelling species, and the larger red-tailed hawks, which are often spotted perched on highway power poles. Some of the rarer sightings include peregrine falcons, only recently removed from the U.S. Endangered Species list, and ferruginous hawks, a grassland raptor that’s listed as a sensitive species in Washington State.
Scientists know surprisingly little about the size of most raptor populations or exactly where they go on their spring and fall migrations. But this kind of information is critical if the habitat these birds require is to be protected. Speaking of the importance of small hawkwatch sites as well as the big, famous ones, Kent Woodruff says, “When I try to describe Chelan Ridge, I use the analogy of a human body with veins and capillaries. The veins are bigger, but the capillaries are also critically important for the health of the system. This migration corridor at Chelan Ridge is a capillary to the main veins of migration in North America-but still, it’s important that each capillary stays healthy and continues to function.”
Additional Teacher Resources
U.S. National Park Service, Bird Species and Distribution in Yukon-Charley Rivers National Preserve: Northern Goshawk Northern Goshawks are agile, woodland hawks characterized by their quick and powerful wing beats followed by extensive glides. This publication gives a brief overview of the natural history of the species.
U.S. Geological Survey, Northern and Rangeland Birds of the United States: Natural History and Habitat Use of the Northern Goshawk?Accipiter gentilis
A brief natural history of the northern goshawk including range, status, habitat, nesting, food and a few additional references.
U.S. National Park Service, Bird Species and Distributions in Yukon-Charley National Preserve: Red-tailed Hawk
A brief natural history of the Red-tailed hawk that provides a general description as well as habitat, vocalization, nesting habits, diet, and distribution.
U.S. Forest Service, Oregon Department of Fish and Wildlife: Swainson’s Hawks?The Oregon-Argentina Connection
Wildlife Diversity biologists in eastern Oregon are using satellite technology in an international effort to determine migration routes and wintering grounds for the Swainson’s hawk, a sensitive species in Oregon. This article explains the processes of telemetry and the efforts being made in eastern Oregon.
Hawkwatch.org: Banner Year for Satellite Telemetry Deployments
An extremely informative report on efforts being made to track hawk migration using telemetry.
