justnorth posted on January 30, 2007 21:49 :: 1281 Views
Bald eagle numbers this winter along the Lower Wisconsin River corridor are almost double last year’s count according to an aerial survey conducted earlier this month by the Department of Natural Resources.
Biologists counted 481 eagles, including 324 adults and 157 immature birds, along the 180-mile survey route running from the Petenwell Dam spanning the Wisconsin River in Adams/Juneau counties to the river’s confluence with the Mississippi River in Crawford County.
“We observed the majority of eagles concentrated along the river from Sauk City through to the Mississippi River,” said Bryan Woodbury, DNR wildlife biologist at Spring Green.
This year’s total is almost double the 244 eagles counted during the 2006 aerial survey, but still below the record 614 birds observed in the 2004 survey. Although, Woodbury adds, to put these numbers in perspective, the five-year average running from 2001 through 2005 was 264 eagles.
Also, the number of birds counted along the river corridor may be less than the actual population in the Lower Wisconsin River watershed.
“With warmer temperatures and more open water along the lower stretches of the river this year (during early January when the survey was conducted), eagles seemed to be much more spread out in the river valley, so I suspect we missed some,” noted Woodbury.
Eagle watching in the Wisconsin River valley has become a very popular winter activity and the number of eagles in the area this year “should provide excellent opportunities to view eagles at many locations along the river as well as farm fields and wetlands” in the river valley, he added.
Bald eagles are listed by the federal government as a “threatened” species overall in the United States but within Wisconsin, the state has listed the bald eagle as a species of “special concern.”
Although the general population is doing well, there’s still concern about what has been causing unusual bald eagles deaths along the Lower Wisconsin River corridor beginning in the mid-1990s, pointed out Sean Strom, a DNR wildlife toxicologist based in Madison.
“Many of the eagles collected over the years have shown clinical signs of neurological impairment (nervous system problems), but there are no specific changes in their tissues that give us clues as to what is causing the problem,” Strom said.
Post mortems are conducted at the U.S. Geological Survey National Wildlife Health Center (NWHC) in Madison and consistent “abnormalities” were found in the livers of most eagles collected from the Wisconsin River corridor.
After the mystery illness surfaced in 1994-95, representatives from DNR, NWHC, the U.S. Fish & Wildlife Service, the U.S. Department of Agriculture, the veterinary and wildlife rehabilitation communities, and the Ferry Bluff Eagle Council began sharing information to monitor southern Wisconsin’s over wintering bald eagle population, especially those birds in the Lower Wisconsin River corridor.
The monitoring plan includes what to do if live, sick eagles are found during the winter; transporting birds, if needed, to a wildlife rehabilitator or veterinarian; arranging for dead eagles to be necropsied by NWHC; monitoring roost sites; investigating deaths; sharing information among functions and agencies; and getting the word out to the public about the situation.
Strom offered the following guidelines as to what the public can do if they find a sick or dead eagle:
- Don’t attempt to catch a sick bald eagle. Their talons are extremely sharp. If the eagle is dead, use gloves or a shovel to pick-up the bird, and place it in a heavy garbage bag.
- Call your local DNR conservation warden or wildlife biologist. Federal law prohibits the possession of live or sick bald eagles. They must be turned over to authorities within 48 hours.
- Inform authorities of when and where you found the bird, and if found alive, any signs of injury or illness.
FOR MORE INFORMATION CONTACT: Bryan Woodbury, Wildlife Biologist, Spring Green - (608) 588-2591; Sean Strom, Wildlife Toxicologist, Madison - (608) 264-6121; or Bill Ishmael, Wildlife Supervisor, Dodgeville - (608) 935-1918
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