Unique among North American raptors for their diet of live fish and ability to dive into water to catch them, ospreys are superb fishers and indeed eat little else—fish make up some 99 percent of their diet.
Because of this appetite, these birds can be found near ponds, rivers, lakes, and coastal waterways around the world. They are found on every continent except Antarctica.
Appearance
Ospreys are very large, distinctively shaped birds of prey. They have long legs and large feet with specialized barbs on the pads, hooked talons, and a reversible outer toe that allows them to easily grasp fish with two toes pointing front and two pointing rear. They have a special valve in their nostrils that closes when they plunge into the water. They have slender bodies and long wings. Their strong wings give them extra lift to fly up and out of the water with a heavy fish. They have a black bill with a sharp hook for eating fish. In flight, ospreys will orient the fish headfirst, in a front-to-back direction, to ease wind resistance.
Ospreys are brown above and white below, and overall they are whiter than most raptors. From below, the wings are mostly white with a prominent dark patch at the wrists. The head is white with a broad brown stripe through the eye. Juveniles have white spots on the back and buffy shading on the breast. Females usually have a dark, spotted “necklace”. Their wingspan can be up to 6′ long!
Hunting
Ospreys hunt by diving to the water’s surface from some 30 to 100 feet (9 to 30 meters) up. Hunting Ospreys are a picture of concentration, diving with feet outstretched and yellow eyes sighting straight along their talons.
Ospreys are sometimes confused with bald eagles, but can be identified by their white underparts. Their white heads also have a distinctive black eyestripe that goes down the side of their faces. Eagles and ospreys frequent similar habitats and sometimes battle for food. Eagles often force osprey to drop fish that they have caught and steal them in midair.
Interaction and Migration
Human habitat is sometimes an aid to the osprey. The birds happily build large stick-and-sod nests on telephone poles, channel markers, and other such locations. Artificial nesting platforms are common in areas where preservationists are working to reestablish the birds. North American osprey populations became endangered in the 1950s due to chemical pollutants such as DDT, which thinned their eggshells and hampered reproduction. Ospreys have rebounded significantly in recent decades. The International Union for Conservation of Nature (IUCN) currently lists the osprey’s conservation status as Least Concern. They are protected by the Migratory Bird Treaty Act.
Ospreys are migratory birds. In Maryland, they are here for nesting season from March through September, and then typically migrate to Central and South America for the winter. They typically lay 2-3 eggs, which both parents help to incubate. Osprey eggs hatch in the order they were laid.