The osprey is a bird that has been called the sea hawk, the fish eagle and the fish hawk. It is the sole member of the genus pandion and is the only North American bird of prey that will dive into the water, sometimes becoming completely immersed, in search of food. The osprey's numbers were on the decline to the point where it was severely threatened, but concerted conservation efforts have helped to increase their population.
There is no other bird of prey in the entire world that has a larger range than the osprey, with these skillful hunters inhabiting parts of every continent except for Antarctica. There are a total of four subspecies of osprey, with close variations of the bird found in North America, Europe and Asia, Australia and surrounding islands, and in the Caribbean. Birds such as ospreys, which are classified as raptors, usually will migrate south during the winter since the freezing temperatures of cold climates make it impossible for them to continue to capture fish. In North America, the osprey is found as far north as Alaska and throughout most of Canada during the warmer months. It is present in every one of the lower 48 states and the osprey will spend the winter months in the southernmost states as well as Mexico and South America. The extensive use of pesticides such as DDT was responsible for osprey populations dwindling during the three decades following 1950. The banning of these chemicals, which either poisoned ospreys when the bird ate contaminated fish or caused the shells of their eggs to become too thin, was a key measure in aiding the bird. However, the osprey is still rather rare in certain inland states, but seems to be thriving along the coasts and the Great Lakes.
Ospreys subsist almost entirely on the fish that they are able to capture in the water, so where they live is dictated by where there is water. Ospreys can be found along bodies of waters such as lakes and rivers where they will catch large fish for themselves and their growing chicks to devour. Ospreys have been known to frequent areas where there are ponds as small as 30 or 40 acres in surface area. Marshes that have open areas of water within them, fish-filled mangrove swamps, and seashores commonly are homes to osprey families. The bird can also be found along the coasts of tropical lands and near lagoons.
The tops of telephone poles, tall trees and other high structures are where an osprey may decide to build its large nest of sticks. Ospreys have been known to place their nest on bridges, buoys in the water, utility poles, and on man-made platforms in and around water that are designed specifically for this purpose. Ospreys will mate for life, and the pair of birds will return to the same nest year after year if possible. Where there is a lack of tall trees or other structures, an osprey may decide to build its nest on a cliff or any rocky formation available. In some instances, ospreys will form colonies, nesting in numbers near water that can sustain their dietary needs. Ospreys will often add more material to their nests each year, building it up to a great size over time.