Wisconsin's population of bald eagles is on the rise, with nesting pairs spotted in nearly every county in the state.
This year's population is expected to top last year's record of 1,337 nesting pairs, the Milwaukee Journal Sentinel reported.
Surveys of eagle populations are conducted every year by the Department of Natural Resources. In April pilots swooped low over trees to look for adults and eggs in nests, and this month they'll be surveying nests for chicks.
The results show breeding pairs in 67 of the state's 72 counties. Because eagles are primarily fish eaters, many of the nests are along the Mississippi River and near Lake Superior.
Only Minnesota and Florida have more eagles than Wisconsin does.
The densest populations are in the forested areas of Oneida and Vilas counties, which have a combined 283 nesting pairs. Forty years ago there were 108 in the entire state.
One reason the population is thriving in Wisconsin is the weather. Mild winters and open water have kept many eagles from migrating to another state. In addition, young eagles have begun moving to new territories in the southern part of the state.
Another key factor is that newer generations of eagles are more tolerant of humans. DNR wildlife biologist Dan Goltz said one eagle's nest in Sheboygan is so close to a house that the roof was getting covered in eaglet droppings.
Birders and others have seen eagles flying in Milwaukee and Washington counties in recent years, but no nests have been officially spotted.
"I am sure that on the horizon we will see them nesting there," said Marty Johnson, also a DNR wildlife biologist.
Nests are also absent in Kenosha, Kewaunee and Walworth counties.
Eagle populations are thriving on the Fox River in northeastern Wisconsin. One reason might be the ongoing cleanup of polychlorinated biphenyls, or PCBs, from the river. Wildlife biologists are finding lower PCB levels in the eagles' blood samples over the last three years, although they stop short of saying the river cleanup is directly responsible.
The bald eagle was taken off Wisconsin's endangered species list in 1997 and the federal list in 2007. Only Minnesota and Florida have more eagles than Wisconsin does.