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osprey (pandeon haliaetus) Class: Aves Order: Falconiformes Family: Pandionidae Species: Pandion haliaetus Last updated Fall 2008 Natural History General Description: The osprey, sometimes known as the fish hawk, is a large raptor that typically weighs between 1200-1900 grams (2.64 - 4.18 lb.). As with most raptors, the female is generally 1/3 larger than the male. When observed in flight, it appears dark brown from above and white from below. Light brown breast banding, present in both sexes, is usually more prominent in females and can resemble the appearance of a "necklace." The beak is black, in contrast to the white head which is masked by dark brown, from the blue colored cere, around the light yellow eye and down the nape. (Eye color in juveniles ranges from red to orange.) The pale blue feet are covered with strong scales. The tail is brown and is crossed by darker brown bands. The wings are long, and the wingspan averages between 3 and 4 feet. When perched, the wing tips extend beyond the tail. In the hand, three unique traits can be observed. 1) An osprey's nostril is long and slit-like and can be closed during underwater dives for fish. 2) Sharp spicules on the underside of the toes aid in grasping slippery prey. 3) The talons are nearly circular in cross section, as compared to most other raptors, which have a flat edge on the backside. The foot structure exhibits a zygodactic condition in which the fourth (outer) toe can face either anteriorly or posteriorly. Thus, there can be two toes forward and two backward or three toes forward and one backward. This is thought to be an adaptation for holding on to a
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wiggling fish. When alarmed, the hackles (the feathers on the back of the head) will be raised, and it will make a "kip, kip" alarm call. Diet and Hunting Strategies: Ospreys' diet is comprised almost entirely of fish. Studies suggest that nearly 98% is fish, while the rest is comprised of frogs, turtles, and small mammals. The types of fish that are hunted depend solely on what is locally available. Osprey will hunt in both fresh and salt water. The size of the prey has been reported to average 25% of the bird's body weight. The osprey employs several methods of hunting depending on prevailing conditions. An individual may hunt from a perch or the air. It will survey the area, using its visual acuity to scan the water below. Once a particular fish is selected, the bird will dive nearly vertically and plunge into the water. It will grab the fish underwater with its talons and immediately fly off to a nearby perch to eat. Osprey feathers are coated with oil during preening, so the water rolls right off and the bird can take off with ease. If it sees a weak fish floating near the surface, it may hunt by approaching from a long gentle glide, plucking the fish effortlessly from the water. Both osprey and bald eagles commonly use this drier, more graceful strategy. Ospreys' hunting success rate is quite high and has been reported to range from 50% to 80% for adults. Of course, the youngsters are going to
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This note was uploaded on 07/29/2011 for the course BIO 65 taught by Professor Yin during the Winter '10 term at Saint Joseph's University.

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Document - osprey(pandeon haliaetus Class Aves Order...

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