Bald Eagles

The Governor Knowles State Forest is home to a large population of bald eagles. You’ll likely catch a glimpse of one of these magnificent birds while hiking along the shores or canoeing on the river.

Bald eagles are large, dark brown birds of prey that do not acquire the distinctive white head and tail until they are adults at five years of age. Bald eagles in Wisconsin weigh eight to fourteen pounds, with a wingspread of up to seven feet. Eagles have keen vision (four to eight times greater than ours), are swift and agile flyers, and possess powerful beaks and talons. All of these features combine to make the eagle a highly successful predator.

When And Where Do They Nest?

Adult bald eagles build and repair their nests from February to March. One to three eggs are laid in March and April. The eggs usually hatch in early May after 35 days of incubation. The young eagles remain in the nest 11 to 12 weeks before they take their first flight; the last of the young leave the nest by late July or mid-August. For about two months after their first flight, the young still frequently return to the nest site and receive food from their parents.

Bald eagles build their nests in tall trees that tower above the forest, located close to a river or lake. Their nests are usually in white pines, but other tree species are used as well, such as red pine, yellow birch, maple and aspen. The nest is a large mass of sticks about three feet deep and five feet across, placed near the top of the tree. Some bald eagles will use the same nest every year, while others will alternate from year to year among two or three different nests in their breeding territory. Some breeding territories have been used for over fifty years.

What Do Bald Eagles Eat?

Wisconsin’s lakes and streams provide an abundant supply of fish — the favorite food of bald eagles. Suckers, bullheads and northern pike make up most of their diet, but bald eagles are resourceful hunters and will feed on waterfowl, shorebirds, and even turtles. They may also take mammals such as baby muskrats and beavers. In winter, eagles scavenge winter-killed deer and small fish provided by ice fishermen. While hunting their prey, bald eagles will perch in trees along the shorelines of rivers, bays, marshes, lakes and ponds.

Management

Bald eagles are sensitive nesters that require undisturbed conditions during late March, April and May. The state forest works to protect eagle nests by routing recreation trails and facilities away from eagle nests. Timber sales are planned to protect nest sites and provide abundant perch trees.

Surveys

Each April a DNR aircraft surveys all known eagle nests to determine which nests are being used. In mid-June the aircraft returns to count the number of young in each nest.

Research

Laboratory analysis of eagle carcasses, unhatched eggs and molted feathers shows if nesting eagles are healthy and relatively free of environmental contaminants. Eagles serve as bio-indicators; a healthy eagle population reflects a healthy lake and stream environment.

Future

With careful land management and pollution control, eagles will continue to be a common sight on the state forest. We can all be proud of the fact that eagles have now been removed from the endangered species list and are now a threatened species.

For more information on eagles, or to report eagle nest locations, contact the state forest office at P.O Box 367, Grantsburg, WI 54840, (715) 463-2898.

Last Revised: Friday February 15 2008