Patrick Durkin: Look up, you may spot ospreys
The piercing calls from high above seemed out of place, almost like when you hear common-loon yodels echoing from Brazilian rainforests in action movies.Yet the whistling, high-pitched chirps did sound familiar. I just couldn’t put them in context with these white pines along the Waupaca River, just two blocks from the county courthouse and hoosegow.
I looked skyward while stepping clear of the tall pines. Just then a large raptor broke from its graceful glide, fully deployed its M-shaped wingspan, and hovered over a light pole high above the gridiron and diamond at Waupaca’s Haberkorn Field. A fish writhed in the bird’s talons as it settled atop a bank of stadium lights.
Perhaps 30 yards away an old wooden telephone pole, minus its crosspieces, stood even taller, topped by a large square nesting platform and roosting bar. As I walked eastward through more pines I noticed another telephone pole, platform and roosting bar.
Everything suddenly made sense. I’ve lived in Waupaca nearly 26 years but somehow overlooked these two osprey platforms. If that osprey hadn’t called as it flew overhead with its fresh catch, I’d probably remain oblivious. I kept watch awhile but never saw its mate. I assume it was away hunting fish or gathering big sticks to remodel a nest.
Then again, I didn’t feel totally clueless. It’s easy to overlook these big fish hawks, overshadowed as they are by bald eagles soaring above our little city or stripping meat and tallow from road-killed deer in nearby ditches.
Plus, I never thought to look for such regal birds in such an ordinary place as two ballfields regularly teeming with small-town athletes and screaming fans. I’m more used to seeing and hearing ospreys along remote waterways while bowhunting elk in Idaho.
Ospreys are adaptable birds of prey, however, and raise young in busier places than ballfields. My colleague Mark Bell in Barron, for instance, photographed an osprey feeding a chick atop a similar high-rise nest while screaming racecars circled a dirt track below, raising dust so thick that Bell often had to cover his camera to protect it from the gritty clouds.
That tolerant, flexible nature helped ospreys rebound from near-extinction the past half-century in Wisconsin. Much like eagles and less famous birds, ospreys barely survived the 1950s and ’60s because of insecticides such as DDT. Wisconsin held less than 90 osprey pairs when the Department of Natural Resources listed the species as endangered in 1972.
Three years before, the state banned DDT, setting the stage for the osprey’s comeback. All it needed then was more nesting sites, but its preferred sites — large, dead tree snags — were scarce because of forestry practices, fewer beaver ponds, and drained and degraded wetlands.
To provide ospreys long-term “housing,” the DNR installed more than 200 nesting platforms from 1972 to 1993. Since then, utility companies such as WE Energies, Wisconsin Public Service, American Transmission Co., and Wisconsin River Power Co. have built countless osprey platforms atop power poles or stand-alone poles. Most such nesting sites have been occupied nearly every year since their construction, and will likely provide 70 years of service before being replaced.
That work also allows utility companies to design nesting platforms that make it difficult for ospreys to build their large nests atop transmission wires, which can kill the birds, burn their nests and short out powerlines. Such efforts are so successful that over 80 percent of Wisconsin’s current 560 osprey pairs raise their young atop manmade nesting platforms.
Wisconsin’s ospreys increased from a low of 82 breeding pairs in 1974 to a record 560 in 2016. The number of nesting pairs passed 100 in 1976, 200 in 1984, 300 in 1989, and 400 in 1995. The population then stabilized for nearly a decade before topping 500 pairs in 2009.
Perhaps coincidentally, that recent increase occurred as cellular-phone companies built more towers, which provided more potential nesting sites. Still, osprey numbers seem to have stabilized at around 550 in recent years, said Carly Lapin, the DNR’s district ecologist in northeastern Wisconsin.
Ospreys never have it easy, after all. They prefer living near water, which puts them in constant competition with bald eagles. Ospreys always lose such turf battles. Eagles constantly harass and commit countless acts of “kleptoparasitism” against them, meaning they wait for ospreys to catch a fish and then steal it.
Ospreys, however, are built for fishing, and patrol clear water to spot their prey more easily. Fish make up about 99 percent of their diet, and ospreys aren’t choosy about the species as long as it’s fresh. They seldom scavenge anything dead, be it fish, fowl or mammal. They’re also the only hawk that can dive 3 feet underwater to catch fish, and then take flight while shaking off like Labrador retrievers.
And they’re skilled. Studies document ospreys catching fish on 25 to 70 percent of their dives, and usually need only 12 minutes to hunt and catch each fish. They even know to hold fish headfirst to improve the aerodynamics as they fly off with their catch. Their feet also have one toe that rotates so two toes face one way and two face the other to hold fish securely.
Not just any waterway supports ospreys. The DNR lists only three osprey nests along the Mississippi River from Grant to Pierce counties, with one in Buffalo and two in Trempealeau counties. And although scores of ospreys nest near the Wisconsin River in central Wisconsin, their numbers in southwestern counties drop to two nesting sites in Sauk, and zero in Iowa, Grant, Richland and Crawford.
Pat Manthey, a retired DNR biologist who worked for years on osprey recovery efforts, speculates that a combination of murky waters, harassing eagles and heavy human traffic might keep ospreys off those riverways.
Still, ospreys have re-established themselves across much of Wisconsin, with active nests in 58 of its 72 counties. Osprey pairs raise one to four chicks between now and August, and then head to Central and South America for winter. They return in April as ice melts from our waterways.
Despite being adaptable, ospreys will never pretend to like Wisconsin’s winters.
Note: To watch nesting ospreys on live “osprey cams” at sites such as the Woodland Dunes Nature Center near Two Rivers, or the Neustadter Nature Center at Collins Marsh near Reedsville, visit these links: http://www.woodlanddunes.org/osprey-cam/, and http://www.ustream.tv/channel/collins-marsh-osprey.