This is my favorite bird of prey. Isn't it magnificent? I was blessed to have this Osprey near our campsite on the Provo River, in the Wasatch Mountains of Utah.
The adult is blackish above, white below; head is mostly white with a wide, black mask through its eyes. The male and female look mostly alike, however, the female is slightly larger than the male and may have a more pronounced band across her upper breast.
The Osprey is 23-24 inches long (58-62 cm). Wingspan up to six feet (183cm).
The Osprey flies with a gull-like kink or crook in its wings, showing a black "wrist" patch when seen flying overhead.
Male and female are presumed to winter separately, then meet back on the breeding ground due to territorial fidelity. They arrive at the nest site within days of each other, usually the male first.
Early in the season, the male performs a "Sky Dance", a form of advertising for a mate and announcing territorial ownership.
Copulation occurs very often prior to incubation; as many as 15-20 times a day, for a three-week period. They mate for 10-20 seconds each time.
The nest is is 2 to 3 feet in height, (up to 7 feet if used for many years); about 5 feet in diameter; the inner cup is 2½ feet in diameter. Made of large, forking branches outside; small branches inside; and lined with moss, bark, twigs and grass.
It is built in a spot with good visibility in all directions, often at the crown of a tree. Nests may be built singly, or several may be close together in a loose colony. The number of nests in a locality is related to the abundance of food in the area.
The male does most of the collecting of material for the main structure, while the female adds materials to the lining. A completely new nest can be constructed in seven to ten days. Often, an old nest is renovated. Branches for the platform are about 20" (50cm) long and are collected not from the ground as you might expect, but from the dead limbs of trees.
Picture this: the Osprey lands near the end of a dead branch, and its weight breaks the branch, which it then carries in its feet to the nest. Branches may also be broken off as the bird grabs them in flight.Some nesting material that falls from the nest may be picked up and reused.
The incubating bird sits very low in the nest. At night, the female does most of the incubation. During the day, she also does most of the incubating, except when the male brings her food. Then she flies to a nearby perch to consume the food, returning when finished. While incubating, the female may leave the nest to defecate.
Eggs: two or three, whitish, with reddish brown blotches.
Incubation: 34 -40 days, by male and female. One brood per year.
Nestling Phase: seven to eight weeks (unable to fly)
Fledgling Phase: four to eight weeks (able to fly, but roost in nest at night)
|Range Map of Osprey - Peterson Field Guide|
(Click on Photos to enlarge)
Provo River, Coalville, Utah (Utah)
Stillman Creek, Heber Canyon, (Heber) Utah
Snake River, Grand Teton National Park, (Teton) Wyoming (Wyoming)
Peterson Field Guide to Birds of North America - (Peterson) Roger Tory Peterson © 2008
Guide to Bird Behavior (Volume 3) - (Stokes) Donald & Lillian Stokes © 1983
Many thanks to my friend, Tom Blackford, who found this video for me to use here: