Early last winter, Marge Gibson, a raptor rehabilitator from Antigo, nursed three injured bald eagles back to health and helped release them over the frozen waters of the Lower Wisconsin River.

Now those eagles, so carefully tended by Gibson, have returned the favor. All three birds wore radio transmitters when they were released. This winter, volunteers, including wildlife biology students from UW-Madison and members of the Ferry Bluff Eagle Council, have followed the beeps emitted by those transmitters.

The result has been a fascinating inside look into the everyday life of the bald eagles who spend their winter along the Lower Wisconsin River. Jeb Barzen, a member of the Ferry Bluff Eagle Council and director of field ecology for the International Crane Foundation, helped oversee the project and said Friday it was a unique effort because most such radio tracking has been done only during the summer months.

Researchers, in following the eagles on their daily flights, discovered first of all that rehabilitated eagles can do quite well when released into the wild. The birds survived and thrived and have departed for their summer haunts.

More important, Barzen said, the released birds provided valuable insight into the comings and goings of the eagles and their day-to-day meandering, information on where they go for a quick meal or where they hide out for a good night's sleep. Over the course of the winter, Barzen said, the birds led researchers to five roosts which before this winter had been unknown. Four of those new roosts were discovered by trackers following just one of the birds, an enormous adult female who proved to be an inveterate traveler over the winter, flying in a single day from the river to Devils Lake and back.

Such behavior, Barzen said, showed that the wintering birds move about considerably more than was previously believed.

The information gained, Barzen added, is important not just because it adds more to our knowledge of the birds and how they live but also because it provides more information that will allow us to better protect those areas relied upon by the birds.

And, like all good research, the winter's project revealed mysteries and raised perplexing, intriguing questions. The two immature birds had never been to the river, Barzen said, and had absolutely no knowledge of places to go for food or for roosts. Yet, one day, he added, one of the immature birds took to the air and flew to the Mississippi River where hundreds of other eagles were gathered feeding on fish. How did it know to go there? Barzen asked. How did it communicate with the other birds?

The last of the birds, one of the immature eagles with tag number 614, headed north on Feb. 21. Council member and tracker Rich Van was, at the same time, happy and sorry to see it go.

"It is a strange feeling," he said of the bird's departure. "Like a satellite leaving the solar system, its signal too weak to speak to us anymore; the birds are all gone, soaring in their orbits to places only they will know."

Illustration: File Photo Among the eagles tracked over the winter along the Lower Wisconsin River was this enormous female adult, held here by raptor rehabilitator Marge Gibson.

All content © Wisconsin State Journal and may not be republished without permission.

All archives are stored on a SAVE (tm) newspaper library system from MediaStream Inc., a Knight-Ridder Inc. company.

Copyright © 2001 Wisconsin State Journal