Based on recent DNA testing, ospreys are thought to be more closely related to eagles, hawks and Old World vultures than previously thought. Like most female birds of prey, female ospreys generally are larger than males. In the Chesapeake Bay, unlike other regions, most ospreys do not start breeding until they are five to seven years old. Many of the over-water structures that are necessary to protect them from predators already have ospreys in residence, so new breeders must either displace older, established nesting birds or find another, perhaps marginal site that others have refused for good reason. Their habitats include shallow water estuaries, lakes, and rivers.
Ospreys usually mate for life.
March ushers in a five-month period of partnership to raise their young. The eggs are approximately the size of very large chicken eggs, mottled and the color of cinnamon. Osprey eggs incubate for about five weeks. After hatching, the 2-ounce chicks become fliers within eight weeks. When food is scarce, the first chicks to hatch are the most likely to survive.