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Osprey
Pandion haliaetus
Family: PANDIONIDAE
Order: Falconiformes
Spanish Common Name: Gavilán pescador
French Common Name: Balbuzard pêcheur
(c) Shawn Carey |
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Natural History
Appearance
The Osprey weighs three to four pounds, has a wingspan of up to six feet, and is approximately two feet long. Plumage is largely dark brown on top and white underneath. The bird has a black, sharply curved bill, and a white crown and head, with a dark band extending back from behind its yellow eyes. The female is larger than the male, and frequently has a speckled brown necklace across the upper chest. The bird's four pale toes are tipped with long black talons. Barbed pads on their feet and a reversible outer toe help the birds grip slippery fish. In flight, the underwings show dark patches at the wrist (crook), and dark bars at the trailing edge and wing tips.
Habitat
Ospreys live along seacoasts, inland bays, freshwater reservoirs, and large rivers and lakes, wherever large concentrations of fish are available. They breed in a variety of shallow water habitats, including boreal forest ponds, desert salt-flat lagoons, mangrove and salt marsh islands, and temperate and tropical lakes and seacoasts. They winter in both coastal and interior areas with shallow, clear water nearby.
Feeding
Ospreys subsist almost entirely on live fish. Prey consists of species that typically school at the water's surface or swim in the shallows. Birds hunt on the wing, often hovering over the water when they spot a fish, and then plunging into the water feet first to grab it with their powerful talons. When an Osprey emerges from the water with its catch, it uses its feet to turn the fish headfirst to reduce aerodynamic drag. The bird then flies off with the fish to an elevated perch, often near the nest, and eats it.
Reproduction
Ospreys can reach sexual maturity in three years. At this time, males generally select nesting sites, which are typically close to water, open to the sky, and safe from predators. Locations include treetops, cliffs, large shoreline boulders, and even the ground on small, inaccessible islands. The birds also readily use manmade structures, such as utility poles, channel markers, duck-hunting blinds, and platforms designed especially for Ospreys. Nests are large, built of sticks, and lined with bark, grass, algae, and sometimes, plastic bags. The clutch usually consists of three eggs, which are incubated mostly by the female. Males occasionally pitch in, but they mainly provide their mates with food during the 38-day incubation period. Females then care for the brood, and males continue to provide food. Offspring fledge when they are about 50 to 55 days old, but depend on their parents for nourishment for another 8 weeks.
Migration
Most Ospreys breeding in North America are migratory, except for permanent resident populations in southern Florida, the Caribbean, the Gulf Coast, and Baja, Mexico. American and Canadian breeders, which winter in Central and South America, begin their southbound journeys in August. They return north between late February and April. Migrants travel alone. An Osprey nesting in central Quebec and wintering in southern Brazil may cover more than 120,000 miles during its lifetime.
References
Poole, A. F., R. O. Bierregaard, and M. S. Martell. 2002. Osprey (Pandion haliaetus). In The Birds of North America, No. 683 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.
Kaufman, Kenn. Lives of North American Birds, Houghton Mifflin Company, New York, 1996.
Sibley, David Allen. The Sibley Guide to Birds. Alfred A. Knopf, New York, 2000.
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