Researchers hope to gain insight from recovered eagles
Trio had West Nile virus, will be released later this month
By Rick LaFrombois
Wausau Daily Herald
Sunday, January 11, 2004
ANTIGO - Researchers soon will release three immature bald eagles that have recovered from the West Nile virus, and they plan to study the disease's long-term effects on the birds of prey.
The sick eagles were brought to the Raptor Education Group in Antigo the past year and are among the first birds known to recover from the seasonal infection transmitted by mosquitoes.
They have being nursed to full strength in the world's largest eagle flight room in the world, which stands 150 feet long and 30 feet high.
Marge Gibson, executive director of the wildlife rehabilitation center, and Nick Derene, 22, a graduate student from the University of Wisconsin-Stevens Point, will track the birds with satellite and radio transmitters to learn how they fare in the wild.
And they say their research could even provide indications of how humans might react long term to the virus.
The first outbreak of West Nile in the contiguous 48 states occurred in 1999. The virus since has spread among birds, humans and mosquitoes to every state. About two in every 10 people who are bitten by an infected mosquito will contract the illness.
The illness usually is mild but can lead to death. Out of 8,977 human cases of West Nile reported in 2003, 218 people died. There were 13 reported cases of West Nile in Wisconsin and no deaths.
The disease is almost always fatal in birds, Gibson said. Wisconsin's gray-horned owls have been hit especially hard. And the eagle, America's symbol of freedom, courage, and strength, is not immune.
Derene and Gibson will release the three immature eagles Jan. 17 and 18 along the Wisconsin River in Sauk City and just downstream from the dam at Prairie du Sac.
The open water provides ideal habitat for eagles, which love to eat fish. The Department of Natural Resources cited reports of 168 eagles roosting in the area.
Eagles are social birds when they are not breeding between February and April. During mating season, they return to their territory - about 15 square miles - and mate with the partner they've been with for life. They typically raise two to three chicks. Bald eagles have lived up to 50 years in captivity. But they must be in perfect condition to survive long in the wild.
To make it to adulthood, the three immature eagles will have to perform flawlessly. Their vision, which could suffer from the effects of West Nile, must be perfect. And their ability to socialize depends greatly on vocalization, which also could have suffered from West Nile.
The eagle's movements will be tracked - up to 100 miles a day - wherever they range, which could be from Alaska to Kentucky. If the birds stay in the Midwest, Derene and Gibson occasionally will drive to observe them in the wild.
The lightweight transmitter costs $3,500 and does not harm an eagle. The transmitter harness will disintegrate after three years and fall off. But before it does, its satellite signal will bounce off a National Oceanic and Atmospheric Administration satellite every four hours and lead Derene and Gibson to within 300 meters of the eagles. Raptor Education must pay $1,500 a year for the satellite service. Once close enough, a radio signal then will help them locate an eagle in the very tree it's in.
The study is unique in that it's the first of its kind on an animal or bird that has recovered from West Nile and it's the first study of West Nile in bald eagles.
Derene hopes to publish his findings after he completes the study.