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Ospreys are the size of small eagles. In the past, ospreys were considered as the sole members of their own family, Pandionidae. Genetic analysis suggests that they are should be classified as a separate subfamily in the family Accipitridae which contains all other hawks and eagles. There are four subspecies of osprey of which the one which inhabits Eastern North America (Pandion haliaetus carolinensis) is the largest. No other raptor other than peregrine falcons have as broad a range as ospreys ( Poole, 1989; Weidensaul, 1996). The ospreys which breed in the northern United States, Canada, and along the East Coast spend their winters in Central America, the Caribbean, and South America. Twenty percent of the ospreys along the East Coast are along the Chesapeake Bay, 20% are found in Florida, and 12% in Maine.Ospreys are rarely far from a body of water. The ospreys which breed in Northern Asia and Northern Europe winter in SubSaharan Africa, the Middle East, Southeast Asia, and Australia ( Poole, 1989).

In the Mid-Miocene, ospreys were known from fossils in California, Florida, and Austria. Ospreys are also known from 12 Pleistocene sites ( Poole, 1989).

Ospreys almost never eat anything other than live fish although on occasion they have been observed to feed on snakes, aquatic mammals, rodents, aquatic birds, and carrion. The short spines along the surface of their feet, their long, thin talons, and the reflex which allows them to close their foot in .02 seconds have adapted them for catching fish. Ospreys commonly catch fish which represent 15-30% of the bird’s body weight ( Poole, 1989). Ospreys are the only raptor which possesses a zygodactyl foot with 4 toes of equal size (Weidensaul, 2000).

Osprey nests are often close to those of other ospreys. Ospreys build large nests which can be repaired and reused for dozens of years. Most mating occurs in the nest. Ospreys are typically monogamous although single males with multiple females can also occur. Both males and females feed the young and incubate the eggs, although females are the ones which spend the night over the eggs ( Poole, 1989).

Ospreys usually lay three eggs which are about the size of large chicken eggs. Within one month of hatching, nestling ospreys have reached 70-80% of their adult weight. Before the end of two months, the nestlings are ready to leave the nest although the parents may continue to feed them for an additional ten days ( Poole, 1989).

Raccoons represent a major threat to eggs and deforestation limits the number of suitable nesting sites ( Poole, 1989).

While their populations are recovering in the United States because of conservation and the banning of many pesticides, they are threatened in many parts of the world by pesticides, overfishing, and habitat loss (Weidensaul, 1996). Between 1950 and 1970, osprey populations dropped 50-90% ( Poole, 1989).


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