Osprey Information Continued
Osprey are slightly smaller than the bald eagle. They have a mostly white belly, a white head with dark streak through eye. Their wings are narrow, with a dark patch at the bend. These fish-eating raptors live near lakes (such as Yellowstone Lake), river valleys, and in river canyons such as the Gardner Canyon and the Grand Canyon of the Yellowstone River. In early spring, Osprey pairs build nests of sticks in large trees or on stone pinnacles close to water. The female lays 2–3 eggs in May to June and the eggs will hatch in 4–5 weeks. Fledglings have light edges to each dark feather on their backs and upper wing surfaces, which gives them a speckled appearance. Osprey migrants generally return to Yellowstone in April and leave in September.
A recently completed study conducted by park biologists found a significant relationship between the declines in cutthroat trout and osprey reproduction at Yellowstone Lake. Recent increases in the number of young cutthroat trout caught by the Yellowstone fisheries program during the fall netting assessment are encouraging. An increase in cutthroat trout production may lead to an increase in nesting pairs of ospreys and improved nest success at Yellowstone Lake.