Prairie Wanderings: Ospreys are cosmopolitan
By PAUL G. JANTZEN
Contributing writer
In late September, Chuck Grunau called to report seeing ospreys at Marion Reservoir's Hillsboro Cove and at Marion County Lake. He wondered if this was possible.
Actually, seeing ospreys here is very possible. They live, according to one ornithologist, "near both fresh and salt water in almost every temperate and tropical country in the world." Another birder reports ospreys in all continents except Antarctica.
In Kansas, ospreys are most common from early April through May, and mid-September through October. They are seen occasionally in summer, also in winter where open water persists. Ranger Neal Whitaker at Marion Reservoir says ospreys are not uncommon here in spring and fall.
Ospreys remind one of bald eagles which are 30 to 40 inches long and have a completely white head. Ospreys are 21 to 24 inches long with a dark band across the forehead reaching back behind the eyes.
Ospreys feed mostly on fish that swim near the water's surface. The bird hovers at heights of 100 feet or more above the lake. When it sights a fish, it partially folds its wings and dives headfirst. Then, just before striking water, it extends its taloned feet downward and emerges from the water with a fish firmly in its clutches. It carries the fish headfirst to a perch to enjoy its meal.
The long, curved claws, the reversible outer toes, and the sharp projections on the soles of its feet and toes are helpful for handling slippery fish. Ospreys also have downcurved upper beaks.
Eagles sometimes harass the smaller ospreys until they drop their fish. The eagle then snatches the fish before it hits water, leaving the osprey to search for another meal.
These birds of prey are in the hawk family and also are called "fish hawks" and "fishing eagles."
Ospreys build large nests of loosely assembled sticks and leaves, usually near the tops of tall (often dead) trees, but also on utility poles. They keep adding material to the nest until the young leave. They use the same nest year after year, adding to it each year. Other birds may build their own nests in the spaces among the sticks of the osprey's nest.
In Kansas, Goodrich reported in 1945 that ospreys were not known to nest in Kansas. In 2001, Busby and Zimmerman did not even mention ospreys in their Kansas Breeding Bird Atlas. So their nests are not likely to be found here.
Ospreys are attentive parents. The female molts during incubation and brooding times while the male brings food to the nest, postponing his molt until after the young leave. Ospreys feed their young whole fish. In warm weather, the osprey shakes water over its eggs to cool them and to prevent excessive water loss.
Like the bald eagle, the osprey suffered population losses from DDT-contaminated fish. The DDT prevented hardening of their egg shells resulting in reproductive failure.
Several times, Elaine and I have searched for ospreys along the wooded edges of Marion Reservoir without success. With binoculars, I observed a bird across an arm of the reservoir for about a half our but was too far away for definite identification.
