Stop 4: The Osprey Family and Nesting Platform
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Osprey in flight

The osprey (Pandion haliaetus) or sea-eagle is one of the most majestic inhabitants of Nantucket Island. This large raptor has a 5-6 foot wingspan, brown feathers on its back, and a white underside. Its call is high-pitched, as is characteristic of raptors. Ospreys are birds of prey. Their feet are covered with large scales for good gripping and their toes rotate; these adaptations enable them to capture fish swimming within 3 feet of the ocean surface. It is quite a sight to watch large osprey hover high above the water, dive head first and with feet outstretched, then emerge with an unsuspecting fish grasped tightly in its talons!

The osprey has a high-pitched call characteristic of raptors, and is often heard before it is seen. With a 5-6 foot wingspan, this large raptor is easy to spot. Its white head, dark brown back and, particularly, its white underside distinguish it from other large birds of prey.

 
osprey and gull in flight

From a distance where colors and size are difficult to judge, ospreys might be confused with gulls. Ospreys have wider tails and broader wings, and flap their wings with a different angle and shape than a gull, as the adjacent photos illustrate.

The osprey population was decimated in the 1970s as a result of pesticide use, particularly DDT and other chlorinated hydrocarbons. Most pesticides accumulate in the bodies of raptors, including ospreys and bald eagles. DDT interferes with the normal development of eggs in females, leading to the production of very thin eggshells. As a result, most eggs were broken or dented when parents tried to incubate them, and very few chicks hatched. Since the banning of DDT and related pesticides in the U.S., the osprey has made a triumphant recovery.

 

Nesting platforms like the one pictured to your right have lured breeding pairs of osprey into available and healthy environments. When they have built a nest and have been successful in raising young there, they will return year after year. The pair at the Field Station has been nesting here since the pole was erected in 1995; in 2004 the pair raised three chicks.

Ospreys are found on all continents except Antarctica. They nest on Nantucket from March to September, and then migrate to Central and South America for winter.

osprey nesting platform
Osprey and three chicks 2004
 
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Back to the start of the trail Harbor and Barrier Spit Stop 3: Beach Erosion The Ospreys Mowing and Succession Stop 6: How Plants Reproduce The Tangled Web of Vines Plants by the Pond Hidden Treasures at the Pond Wrack Lines at the Beach Folger's Salt Marsh

     The Nantucket Field Station Virtual Nature Trail is a joint effort of the following departments: Biology, Computer Science, Earth & Geographic Sciences, and ECOS. UMass Boston Home Page

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