The Wild Side: A dangerous time of year for eagles
As a child, I remember our family coming to the Northwoods every summer. My mom would make my dad stop so she could take a picture of every deer and eagle we saw. Where we lived, further downstate, we occasionally saw deer, but it seemed different in the northern forest. We rarely saw bald eagles unless we came up north. We camped on Razorback Lake, near Sayner, every summer. Every year, as long as I could remember, we saw the same eagle on the same island. In fact, that eagle was banded as a hatchling in 1977, and lived to the age of 31. It was found dead in 2008, on that same island we saw it perched above for decades. At the time, this eagle was considered to be one of the oldest recorded wild eagles in the Midwest; most do not live to even 25 years old.
Eagles were on the brink of extinction half a century ago. Environmental factors, like the use of pesticides, lead poisoning and loss of habitat had contributed to their demise, and they were listed as an endangered species. Wisconsin had only 82 pairs when we conducted our first eagle nest survey in 1970. Their populations rebounded as protective measures improved, and they were taken off the Threatened and Endangered Species List in 2007. At that time, Wisconsin had about 1,200 breeding pairs of eagles, many of which were located in Vilas and Oneida counties. Our national emblem, bald eagles are still protected by the Bald Eagle Protection Act of 1940. They are protected, carefully monitored and populations are still counted annually. Any dead eagles are collected and sent to the National Eagle Repository in Colorado.
Can you guess what would be the number one cause of death for dead eagles we collect and examine? According to DNR eagle volunteer Ron Eckstein, retired DNR wildlife biologist out of Rhinelander, it is car strikes. This time of year, our eagles are extremely vulnerable to vehicle strikes. Eagles are migratory birds that head south for the winter, but they return to the same nest location every year in late winter to repair their nest, strengthen pair bonds with their mate, and prepare to lay their eggs. Under normal circumstances, bald eagles are opportunistic predators that perch high in a tree, taking off to swoop down and capture prey like fish or waterfowl. They then haul their prey back up to the treetops, where they feed. This time of year, though, food is in short supply. Some food, I should say, like fish is under a thick sheet of ice. Waterfowl are also not readily available. Eagles have adapted to an alternate prey source that emerges this time of year – car-killed deer.
As the snow melts, dead deer that had been encased in snowbanks begin to emerge, and eagles take advantage of the carcasses. This might not seem like a problem, until you consider what is required for an eagle to get airborne. They are not adapted to taking flight from standing on the ground. They need to take six to eight full wing beats, while hopping on the ground, to get enough lift to fly. Unfortunately, eagles often head toward the road for their runway, and collide with vehicles. In the last two weeks, we have collected a few dead eagles, and a couple more have died from their injuries at local wildlife rehabilitators. Dead deer can be life-saving or deadly for eagles. When you see an eagle on the side of the road, keep an eye on them, and reduce your speed until you know they are not going to head toward your vehicle.
The annual eagle and osprey survey is currently under way. If you know of a new nest, have seen changes in a known nest location, or know of an eagle that has died, you can contact Ron Eckstein at 715-365-8927 or Ronald.Eckstein@Wisconsin.gov.
Jeremy Holtz is a wildlife biologist with the Wisconsin DNR and writes a weekly column in the Star Journal. To contact him, call (715) 365-8999.