An adult osprey is 21 to 24 inches in length. The body has black or dark brown feathers above and white belly feathers. The head has white feathers with black patches on its face. There are black tips on the ends of the wing feathers. This bird has a wide, black band on the underside of its tail with a thin, white line at the tip of the tail.
The osprey migrates through Illinois and nests along large rivers and lakes. It winters in the southern United States near the Gulf of Mexico south to Chile. This bird is a carnivore, mainly eating fishes. It will also feed on amphibians, birds and crayfish. It hunts primarily from a common perch or nest in a large tree. The osprey plunges feet first into the water to grab a fish. There is a distinct bend in its wings when it flies. The call of the osprey sounds like "cheep, cheep." Spring migration through Illinois begins in March. An osprey nest is built of dead limbs and placed high in a tree, live or dead, that is located in standing water. The nest may be used for more than one year. Ospreys mate for life and may not breed every year. The female osprey is fed by the male from the time the pair bond is formed until the last of the two to four eggs is laid. Eggs are white with brown markings. One brood of young is raised per year. The male has been known to assist with incubation of the eggs. Fall migration starts as early as July.