For the Birds: Osprey, the other Sea Hawk

Osprey profile
Photo by Mark Zimmerman

By Christine Southwick

Osprey are large birds of prey (wingspan approximately 6 feet) who eat fish almost exclusively. They are unique in that there is only one species of Osprey found world-wide. Their backs are usually dark brown; the head has a distinctive white crest with an impressive dark eye-stripe. The adults have yellow eyes, while the young have orange-ish eyes, the opposite of most raptors.

When flying, Ospreys look more like large gulls than raptors, with their arched wings and bent wrists. When resting on a piling, branch, or open nest, their body profile is more horizontal than other raptors. They have white feet with black talons that are adapted to carry fish while flying — they can use two talons forward and two in back, rather than the more normal arrangement of three in front and one in back, which they use when grabbing sticks to add to their nest.

Osprey open wings
Photo by M.R. Cassidy

They can hover over water, and will plunge feet first to catch their preferred 5-16 inch fish. Osprey have been observed flying a mile or more with a fish dangling head forward as they fly back to their nests. Bald Eagles will sometimes steal fish from Osprey, which will drop the fish, if they can't out-maneuver the eagle. Then they have to hunt all over again.

Osprey fishing
Photo by Doug Parrott

Osprey generally mate for life, with both partners building the nest, and incubating the two-four eggs. Once the young have hatched, the female stays with the nestlings and the male brings the food.

The nests themselves, always near some form of fish-bearing water, are reused yearly and may get as big as seven feet across and five feet deep. Every spring the returning Osprey will renovate their nests, and some huge nests have been used for 70 years. If a storm takes down a nest the Osprey will either rebuild, or start a new nest at a nearby suitable nest site. Their fish-eating practice allows Ospreys to nest on tree tops and open platforms without fear of harassment from crows and hawks.

Osprey feeding a juvie
Photo by Mark Hamilton

Osprey become sexually mature and may start breeding at three to four years, unless there are not enough nesting sites, in which case they may have to wait five to seven seasons. Man-made nesting platforms have been proven to make up for the lack of natural habitat.

Osprey in this area migrate, with some returning in late March while others don’t arrive until late April or early May.

Updated 08-03-2015 12:51pm