Bald eagles aren’t rare in central Wisconsin, but neither do we take them for granted.
Their unique combination of beauty and power force you to stop and watch, whether they’re perched high in a tree or low atop a road-kill’s rib cage.
And so that’s what I did when a bald eagle flew overhead on the final morning of 2017 as I trotted east from Waupaca on County Highway K. Slowing to a walk, I watched the big bird soaring southward over dormant farm fields toward a tree-lined creek.
After looking in the direction from which it had flown, I stopped and unsnapped the iPhone from my belt. Another adult bald eagle sat at the woods’ edge 75 yards across a cut cornfield. Thinking it might fly off to join its mate, I held the phone at arm’s length to avoid frosting its screen with each breath, and hit the record button.
Sure enough, seconds after a pickup truck passed on the road behind me, the eagle pitched off of its perch, flapped toward me until regaining altitude, and flew in the first eagle’s direction.
That was the first bald eagle I’ve seen in that area during winter. My wife and I usually spot them in spring, summer or fall near our home just north of the Waupaca River where it enters the western side of town.
It’s also possible I hadn’t been paying attention. But Jim Woodford, a biologist and program manager at the Department of Natural Resources’ Rhinelander office, confirmed it’s less common to see bald eagles far from big rivers and open water in winter. These big raptors typically congregate in winter along the lower Fox River in northeastern Wisconsin, the lower Wisconsin River west and northwest of Madison, and stretches of the Mississippi River from Wabasha, Minnesota, to Prairie du Chien.
In recent years, however, more eagles are wintering in central and west-central counties. Woodford said the change seems to coincide with shorter winters with less snow and ice cover. In addition, eagle numbers are increasing as they grow more tolerant of humans. He said biologists also speculate that more adult eagles might be staying near their nesting territories year-round to prevent others from moving in.
Bald eagles prefer eating fish when they’re available through open water, but readily scavenge road-killed deer and other carrion when it’s more convenient than fishing. That might explain the eagles I spotted. Deer carcasses seem more common along rural Waupaca County roads than junk-food wrappers and shredded retread tires.
Scientific surveys also show bald eagles are doing well across Wisconsin. The DNR’s 2017 nesting survey reported a record 1,590 occupied eagle nests in March and April last year, 86 (6 percent) more than the 1,504 it documented in Spring 2016.
That was the survey’s 45th year. During the first survey in 1973, researchers found only 108 occupied nests statewide. That was one year after the federal government banned the pesticide DDT nationwide. Besides killing songbirds outright, DDT crippled reproduction in raptors by thinning and weakening their egg shells.
The 2017 survey also documented occupied eagle nests in 70 of Wisconsin’s 72 counties. Kenosha County recorded its first occupied eagle nest last year, which leaves only Milwaukee and Walworth counties without nesting eagles.
Vilas and Oneida counties in north-central Wisconsin — one of the nation’s highest concentrations of freshwater lakes — led the way with 168 and 141 occupied eagle nests, respectively. And although this was the first year the DNR detected no new eagle territories in Oneida County, nest numbers were up overall across that region, which also includes Iron, Taylor, Lincoln, Langlade, Forest, Price and eastern Ashland counties.
That region had 526 nests in 2017, up 15 (3 percent) from 511 in 2016. Woodford’s team reports that this region likely has one of North America’s highest densities of nesting bald eagles. Southwestern Wisconsin, meanwhile, had the greatest percentage increase in occupied eagle nests in 2017, rising 31 percent from 162 to 212. Only northeastern Wisconsin reported fewer eagle nests last year, dropping 3 percent from 176 to 171.
Despite the state’s record eagle numbers, and the temptation to think Wisconsin is nearing its carrying capacity for the big raptors, Woodford said he never underestimates their ability to adapt and live among us.
“I see it leveling out, but if you were to talk to our eagle team 10 years ago, they thought we leveled out just above 1,100 occupied nests in 2007 to 2009,” Woodford said. “Then it started shooting up again.”
Despite the bald eagle’s recovery and removal from the endangered species list, Wisconsin still loses 100 to 150 of them annually to factors besides natural deaths. Woodford attributes about half of those losses to collisions with cars, trucks and overhead wires. About 25 percent of the deaths can’t be explained, and about 10 percent are caused by powerline electrocutions.
The other 15 percent are caused by lead poisoning, either from scavenging deer gut piles contaminated by lead-bullet fragments, or from preying on or scavenging birds and animals killed or crippled by lead-based bullets or shotgun pellets. A 2014 study of 58 dead eagles — sent to U.S. Fish and Wildlife Service offices in Madison from Iowa, Minnesota and Wisconsin — found that 38 percent carried fatal lead concentrations.
Previous research found it unlikely that raptors could accumulate lethal lead levels through environmental exposures. Therefore, they most likely ate lead-bullet fragments while scavenging. The deaths spike from November through January when contaminated gut piles and unrecovered deer are most common.
That’s why some of us have switched to solid copper slugs or bullets for deer hunting, whether with shotguns, or centerfire or muzzleloading rifles. And yes, 15 percent of 100 to 150 bald-eagle deaths annually won’t hurt the population, but I doubt that comforts nonhunters who otherwise have no beef with deer hunting.
If you’d like to see bald eagles this winter, check out events such as Eagle Days Along the Fox River, Saturday and Jan. 21 and Jan. 27 (http://eagledaysalongthefox.org); or Bald Eagle Appreciation Days, Feb. 23-24, in Prairie du Chien. Of course, you could also go to those places on your own, as well as Sauk Prairie on the Wisconsin River and the Mississippi River at Wabasha and other sites.