Female ospreys are larger than males. In North America, male ospreys weigh 1,200 to 1,600 grams and females weigh 1,600 to 2,000 grams. Animal Diversity Web gives an osprey's length as 55 to 58 centimeters and its wingspan as 145 to 170 centimeters. Ospreys live near water, such as rivers, lakes and the coast; ospreys live on every continent except Antarctica. Ospreys eat almost nothing but fish. The osprey typically feeds on fish 4 to 12 inches long. As of November 2026, studies in North America have documented more than 80 different prey species of ospreys. Ospreys do not generally need to drink water, because fish flesh supplies enough water to meet their needs. An osprey flies over the water and hovers, and then it plunges toward the water to catch a fish. Ospreys hunt for fish from the air, flying up to about 40 meters above the water.
National Geographic says ospreys hunt by diving to the water's surface from some 30 to 100 feet up. Ospreys have been known to dive up to one metre below the surface of the water to catch prey. An osprey uses strong, almost horizontal wing beats to lift itself and its prey from the water; ospreys catch fish on about a quarter or more of their dives. How often an osprey catches a fish depends on its own ability, the weather and the tide; some studies have shown that ospreys are most successful at hunting at midtide and when the weather is calm. Breeding ospreys are known to travel as far as 14 km from their nest during hunting forays; in addition, an osprey watches for movement just beneath the surface of the water.
Ospreys have four types of colour receptors in the eye, while people have three; an osprey's eyes also have a very high density of receptors, which gives it much better visual acuity than people have. Ospreys have relatively long legs for a raptor; the underside of an osprey's feet has rough, spiny pads called spicules that help it hold a slippery fish, and an outer toe on each foot can swing around to join the rear toe. In addition, an osprey has a see-through third eyelid, and it closes this eyelid when it dives into the water. Ospreys have dense oily plumage as well as efficient nasal valves that prevent water from entering the nostrils; the pale underside of an osprey's plumage can help it blend into the bright sky.
Widespread use of the pesticide DDT caused osprey numbers to fall in the mid-1900s. Osprey numbers in North America largely rebounded after DDT was banned. The osprey population in the Chesapeake Bay fell to a low of about 1,450 pairs in the early 1970s; by the mid-1990s there were about 3,500 pairs of breeding ospreys in the Chesapeake Bay area. As of November 2026, the Chesapeake Bay Program places the Chesapeake Bay's current osprey population at eight to 10,000 breeding pairs. During the height of the DDT era, breeding ospreys along the Elizabeth River in Virginia disappeared completely; in a 1995 survey of the Elizabeth River in Virginia, only 8 breeding pairs of ospreys were found. A 2014 survey of the Elizabeth River mapped 60 breeding osprey pairs and documented 73 young. As of November 2026, regions where ospreys are particularly abundant include Scandinavia and the Chesapeake Bay region of the United States.
Ospreys build large stick nests on telephone poles, channel markers and other structures; ospreys choose nest structures that can support a bulky nest and that are safe from ground-based predators. Access to trees or man-made platforms to nest in is crucial for the survival of ospreys. Osprey pairs use the same nest year after year; ospreys add new material to their nest each year, so the nest can become huge. An osprey lays two to four eggs over several days, each one 1 to 2 days after the one before. Osprey incubation starts when the first egg is laid, so the eggs hatch in the order in which they were laid; osprey eggs hatch after about 40 days of incubation. Young ospreys take their first flight at about 50 to 55 days old. Ospreys are sexually mature at about 3 years old, but may not breed until age 5 where nest sites are scarce.
Most ospreys breed in the north and migrate south for the winter, and ospreys migrate alone, not in flocks. Some ospreys do not migrate: those that live at lower latitudes, such as the Caribbean, are mostly sedentary. Most ospreys that nest in the UK spend the winter in West Africa. Ospreys heading south from the Midwest and East Coast populations average about 130 miles a day. On a normal migration day, an osprey's ground speed is between 20 and 30 miles per hour; the yearly migration of UK ospreys is a round trip of some 12,000 km. The osprey subspecies Pandion haliaetus carolinensis breeds in North America and the Caribbean and winters in South America. Ospreys arrive in the Chesapeake Bay region in early March and stay through spring and summer. Ospreys can regularly cover over 100 km a day on migration, or even fly non-stop for 48 hours.
Osprey tracking by satellite began in 1995 in Sweden; by the mid 1990s, satellite transmitters were being made that weighed just a bit more than an ounce. Satellite locations of tagged ospreys were accurate down to about 100 yards in ideal circumstances, but more often to within a mile or so; Since 2011, researchers outfitted sixteen ospreys in New Hampshire with GPS satellite transmitters. Each satellite transmitter used on the New Hampshire ospreys weighs 30 grams; given a fully charged transmitter, researchers can get an osprey's location every two minutes. Each transmitter communicates with a network of orbiting satellites on an every-third-day schedule; New Hampshire Public Radio reported in 2013 that the biggest hurdle for migrating New Hampshire ospreys is the weather over the Gulf of Mexico. Some young ospreys tagged on Martha's Vineyard cross over 1,000 miles of the Atlantic Ocean before they get to the Bahamas.
