NELSON, Wis. - The Wisconsin Department of Natural Resources is planning to strap small GPS units on golden eagles over the next three years to see where the birds go when they migrate from western Wisconsin and eastern Minnesota.
The golden eagle is mostly a western bird and is plentiful from the Dakotas west to the Pacific Ocean. The national bird of Mexico, it also lives in northern Ontario, where it's listed as a species of concern.
Though it's not unusual to see one in Wisconsin, the prevailing wisdom used to be that there weren't many here.
But a one-day census last month by 100 trained volunteers counted 70 in western Wisconsin, eastern Minnesota and northern Iowa, including 50 seen in Wisconsin's Buffalo County.
Last year's one-day census of the same area tallied 37 golden eagles, including 31 in Wisconsin.
"We assume these birds are probably coming from northern Ontario, and this (GPS) device will tell us if that's true," said Scott Mehus, education program specialist at the National Eagle Center in nearby Wabasha, Minn.
He added that it's possible more golden eagles are being counted because officials are now noticing them. "Plus, we can learn more about where they're going while they're here and their daily territory."
The Wisconsin DNR has issued trapping permits and provided staff to monitor the trapping sites in the state. The goal is to trap and track two golden eagles per year for the next three years.
So far, no golden eagles have been fitted with the GPS units. If none are captured, Mehus said a golden eagle accidentally caught last fall in a coyote trap in Buffalo County, now recovering from puncture wounds at the University of Minnesota, will be fitted with a GPS unit. It will then be returned to the wild next month.
The Mississippi River is a haven for bald eagles during the winter since this stretch never ices over and the birds can catch plenty of fish. In the one-day census last month when 70 golden eagles were sighted, 390 bald eagles also were counted.
While much research has been done on golden eagles elsewhere in the United States, very little is known about them in the Mississippi River Valley.
Few golden eagles are seen deeper into Minnesota or Wisconsin, away from the Mississippi River region. For whatever reason, the birds are choosing to stay here from mid- to late October until late February.
"We want to know how they're using the Mississippi River Valley during the winter, what their habitat choices are — are they staying in one place or wandering around — and we need to know that to manage them on both sides of the river," said Mark Martell, director of bird conservation for Audubon Minnesota, who is helping with trapping efforts.
Wildlife biologists also want to know where they're going to breed and the route they're taking to their nesting sites.
Mehus and Martell suspect the golden eagles spending their winters in Wisconsin and eastern Minnesota are probably from Canada. One reason: Mehus said it's common for golden eagles in the western U.S. to perch on telephone poles but in 14 years of working in eastern Minnesota, he's seen only one golden eagle do that.
With whatever information they find on the eagles' winter sites, officials hope to preserve the habitat.
The $3,700 GPS units are provided by the Minnesota DNR, along with funding from private sources and the U.S. Fish and Wildlife Service. Satellite time to track the golden eagles will cost $1,500 per bird each year.
Biologists hope the GPS units, which weigh about 3 ounces, will stay in operation for four to five years.
Information from: Milwaukee Journal Sentinel, http://www.jsonline.com