Field Guide/Birds/Pandion haliaetus
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| Pandion haliaetus |
The Osprey (Pandion haliaetus) is a medium large raptor which is a specialist fish-eater with a worldwide distribution. It is sometimes known by the misnomers Fish Hawk or Fish Eagle.
It has white underparts and long, narrow wings with four "fingers", which give it a very distinctive appearance.
The Osprey is particularly well adapted to its diet, with reversible outer toes, closable nostrils to keep out water during dives, and backwards facing scales on the talons which act as barbs to help catch fish. It locates its prey from the air, often hovering prior to plunging feet-first into the water to seize a fish. As it rises back into flight the fish is turned head forward to reduce drag.
It breeds by freshwater lakes, and sometimes on coastal brackish waters. The nest is a large heap of sticks built in trees, rocky outcrops, telephone poles or artificial platforms.In the Chesapeake Bay, unlike other regions, most ospreys do not start breeding until they are five to seven years old. Many of the structures they need to nest and protect them from predators are taken. If there are no nesting sites available, young ospreys may be forced to delay breeding.
Ospreys usually mate for life. In March they begin a five-month period of partnership to raise their young. Females lay 3-4 four eggs by late April, and rely on the size of their nest to conserve heat. The eggs are approximately the size of chicken eggs, and cinnamon colored. The eggs generally incubate for 5 weeks. After hatching, 2-ounce chicks become fliers within eight weeks. When food is scarce, the first chicks to hatch are most likely to survive.
European breeders winter in Africa. American and Canadian breeders winter in South America, although some stay in the southernmost USA states such as Florida and California. Australasian Ospreys tend not to migrate.
The Osprey is the official bird of Nova Scotia in Canada and Sudermannia in Sweden.
The Osprey differs in several respects from the other diurnal birds of prey, and has always presented something of a riddle to the taxonomist. Here it is treated as the sole member of the family Pandionidae, and the family listed in its traditional place as part of the order Falconiformes. Other schemes place it alongside the hawks and eagles in the family Accipitridae—which itself can be regarded as making up the bulk of the order Accipitriformes or else be lumped with the Falconidae into Falconiformes— and others again group it alongside the other raptors in a greatly enlarged Ciconiiformes.
Twenty to thirty years ago, ospreys in the Chesapeake region faced possible extinction, because the species couldn’t produce enough young to maintain the population. Since the ban of DDT in the early 1970s, the ospreys, as well as other affected species are making significant recoveries.
