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Satellites Help Reveal Secrets of Epic Goose Migration |
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Brian Handwerk for National Geographic News |
| December 27, 2002 |
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Researchers continue to search Irish wetlands for two light-bellied brent geese named Arnthor and Austin, who disappeared during a satellite-tracking project following the birds' annual migration. Four other geese tracked during the project have already provided researchers with new information on the bird's traditional migration route from Ireland to Arctic Canada. The findings may help wildlife managers protect the threatened species in the future. The Wildfowl and Wetlands Trust, a United Kingdom-based international wetland conservation charity, began satellite tracking of migrating light-bellied brent geese last summer with support from the National Geographic Society. Using newly available technology, scientists fitted the birds with lightweight, battery-operated transmitters to pinpoint the bird's location for researchers. Light-bellied brent geese (Branta bernicla hrota) undertake the longest, and likely most dangerous, migration of any goose species. The epic flight takes the geese from their winter home in Ireland to breeding areas on the tundra of the Queen Elizabeth Islands in the high Arctic region of Eastern Canada. "Few people in Ireland know that the geese they see in winter travel all the way to Canada in the summer," said James Robinson of the Wildfowl and Wetlands Trust. Migration Information Drives Conservation Efforts "Two of the six birds originally tagged made the complete epic round journey back to Ireland and can be seen occasionally on Strangford Lough," wrote Tony Richardson, managing director of the Wildfowl and Wetlands Trust, in a year-end review of the project. Two other tagged geese died during migration, but not before providing researchers valuable information about migration and breeding habits of the species. Understanding the patterns of the long migration is essential to enacting conservation measures to protect the geese. The Eastern Canada population of light-bellied brent geese is relatively small, comprising perhaps only 20,000 birds. It is currently protected by the EU, Canada, and the African-Eurasian Waterbird Agreement. "We were very interested in learning more about the migration route of this bird," said James Robinson of the Wetlands and Wildfowl Trust. "We had to do it remotely, because we knew the geese passed through very remote areas with no humans. In Europe we can often use a network of people who spot migrating birds and record their movements." The bird's arduous migration first entails a long sea-crossing between Ireland and Iceland. The geese "stage" in the island's Alftanes area just west of Reykjavik, where they fatten up before continuing their migration. While the bird's winter weight hovers between 2.9 to 3.5 pounds (1.3 to 1.6 kilograms), their weight grows to approximately 4.4 pounds (2 kilograms) before departing for the Canadian Arctic. From Iceland, the geese embark on a perilous 1,865-mile (3,000-kilometer) flight over Greenland's ice cap to their Canadian breeding grounds. Robinson noted that the study also provided information on bird behavior at the breeding site. "We learned some new things about where these birds were spending the summer," he said. Migrating Geese Run a Gauntlet of Predators Researchers were most interested in gathering data on the bird's migration from Iceland to Canada and, later, their return migration to Ireland. Researchers fitted the birds with tags during their stopover in Iceland, rather than their original departure grounds in Ireland, to conserve battery power. "The bird Oscar never left Iceland," Robinson recalled. "Some kids collecting eiderdown found him. He was likely the victim of a bird of prey, something like a Gyr falcon." The death highlighted the predatory dangers the geese face in addition to the hazards of migration. The geese began moving in mid-June. The bird Arnthor was lost on Disko Island, off the west coast of Greenland. "We knew that there were probably hunters in this area," Robinson said. "Given that the transmitter just stopped dead, we suspect that it might have been shot in Greenland. But we don't know what's happened to that bird. That's one of the ones we're still looking for in Ireland." Four birds were tracked across Canada, including a goose nicknamed Kerry. The bird later perished. In July, Canadian Wildlife Service Officials near Resolute Bay on Cornwallis Island decided to look for Kerry on the ground because he was transmitting from an area close to their station. After fruitlessly searching goose-populated wetland areas, the officials realized that when they were in the town of Resolute Bay the signal grew stronger. "They tracked it to a house and knocked on the door," Robinson recalled. "The guy inside said, 'Yeah, I shot the goose.'" The bird was found hanging in the hunter's freezer, though researchers view the incident a bit differently than one might expect. "For the goose it was unlucky, but it was actually a fortunate occurrence because it identifies a threat that we didn't know these birds were under," Robinson said. In light of Kerry's death, Wetlands and Wildfowl Trust staff would like to further investigate Arctic hunting and to learn how many birds are shot each year. Subsistence hunting is currently legal in the Arctic unless the number of birds taken is unsustainable. Hugh and Major Rutledge, two surviving geese from the study, have successfully returned to winter in Ireland. Though their transmitters have lost power and detached as planned, they are distinctively tagged and have been spotted by project volunteers. The same volunteers continue to search for the two geese as yet unaccounted for. "We'll be going around Ireland to various estuary areas to try to locate Austin and Arnthor," said Robinson. "We're expecting to see Austin in Ireland somewhere this winter." Austin last transmitted on Ellesmere Island back in September, before the batteries on his transmitter expired. Results from the project have been very positive, filling in many holes in knowledge of exactly when and how the birds make their annual trek. "We now have a good indication of where the birds were going and where their important staging areas are," Robinson said. "So we're trying to get experts and policy makers together, in all the countries along the route, to work on a concerted flyway management plan. Without the project we might never have been able to do this." Recent Bird Stories by National Geographic News: Farmers, Conservationists Seek Return of Barn Owls Seasons of a Birder's Life Do Some Birds Cheat to Avoid Inbreeding? Water-Diversion Plan Threatens California's Salton Sea National Geographic Bird Resources: Bald Eagles: Come Back From the Brink Experience the Sights and Sounds of Eagles Recent "Birder's Journal" Stories from Robert Winkler: Birder's Journal: Ghost Town's Curse Haunts New England Forest Birder's Journal: A Morning With Migrants Birder's Journal: This Warbler Is a Master of Deception Birder's Journal: Seduced by Dueling Thrushes Birders Journal: Attack of the Flying Goshawk Nationalgeographic.com Bird-Watching Sites: Boston Area Chicago Area Florida Keys Area Maine's Acadia National Park Mount Rainier New Orleans Area New York City Area North Carolina's Outer Banks Philadelphia Area Portland Area Rocky Mountain National Park Salt Lake City Area San Francisco Area Santa Fe Area South Dakota's Black Hills Utah Washington's Olympic National Park Wyoming's Grand Teton National Park Yellowstone National Park Yosemite National Park From the National Geographic Store: Guide to North American Birds Portable Birdsong Identifier Birder's Journal Songbirds Puzzle Additional Information from Related Web Sites: American Bird Conservancy Fish and Wildlife Service Bird Web Site National Audubon Society Environmental Protection Agency: Bird Conservation |
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