Habitat
Unable to dive to more than about three feet below the water's surface, Ospreys gravitate toward shallow fishing grounds, frequenting deep water only where fish school near the surface. Ospreys nest in a wide variety of locations, from Alaska to New England,
Montana to Mexico, Carolina to California; their habitat includes almost any expanse of shallow, fish-filled water, including rivers, lakes, reservoirs, lagoons, swamps, and marshes. Whatever the location, Osprey nesting habitat must include an adequate supply of accessible fish within a maximum of about 12 miles of the nest; open, usually elevated nest sites free from predatory mammals such as raccoons, and a long enough ice-free season to allow the young to
fledge.Back to top
Food
The Osprey is the only hawk on the continent that eats almost exclusively live fish. In North America, more than 80 species of live fresh- and saltwater fish account for 99
percent of the Osprey’s diet. Captured fish usually measure about 6–13 inches in length and weigh one-third to two-thirds of a pound. The largest catch on record weighed about 2.5 pounds. On very rare occasions, Ospreys have been observed feeding on fish carcasses or on birds, snakes, voles, squirrels, muskrats, and salamanders. Ospreys probably get most of the water they need from the flesh of their prey, although there are reports of adults drinking on hot days.
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Nesting
Nest Placement
Ospreys require nest sites in open surroundings for easy approach, with a wide, sturdy base and safety from ground predators [such as raccoons]. Nests
are usually built on snags, treetops, or crotches between large branches and trunks; on cliffs or human-built platforms. Usually the male finds the site before the female arrives.
Nest Description
Osprey nests are built of sticks and lined with bark, sod, grasses, vines, algae, or flotsam and jetsam. The male usually fetches most of the nesting material—sometimes breaking dead sticks off nearby trees as he flies past—and the female arranges it. Nests on artificial platforms,
especially in a pair’s first season, are relatively small—less than 2.5 feet in diameter and 3–6 inches deep. After generations of adding to the nest year after year, Ospreys can end up with nests 10–13 feet deep and 3–6 feet in diameter—easily big enough for a human to sit in.
Nesting Facts
| Clutch Size:
| 1-4 eggs
|
| Number of Broods:
| 1 brood
|
| Egg Length:
| 2.2-2.7 in [5.5-6.8 cm]
|
| Egg Width:
| 1.6-2.0 in [4.2-5 cm]
|
| Incubation Period:
| 36-42 days
|
| Nestling Period:
| 50-55 days
|
| Egg Description:
| Cream to pinkish cinnamon; wreathed and spotted with reddish brown.
|
| Condition at Hatching:
| Capable of limited motion. Covered with down and with eyes open.
|
Back to topBehavior
Adept at soaring and diving but not as maneuverable as other hawks, Ospreys keep to open areas,
flying with stiff wingbeats in a steady, rowing motion. Primarily solitary birds, they usually roost alone or in small winter flocks of six to ten. Nesting Ospreys defend only the immediate area around their nest rather than a larger territory; they vigorously chase other Ospreys that encroach on their nesting areas. In breeding season, males perform an aerial "sky-dance," sometimes called "fish-flight." With dangling legs, often clasping a fish or nesting material in his talons, the male
alternates periods of hovering with slow, shallow swoops as high as 600 feet or more above the nest site. Sustaining this display for 10 minutes or more, he utters repeated screaming calls while gradually descending in an undulating fashion to the nest. Back to top
Conservation
Ospreys are a conservation success story, and their numbers grew by approximately 1.9% per year from 1966 to 2019, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of
1.2 million and rates them 7 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. Osprey numbers crashed in the early 1950s to 1970s, when pesticides poisoned the birds and thinned their eggshells. Along the coast between New York City and Boston, for example, about 90% of breeding pairs disappeared. Osprey studies provided key support for wider legal arguments against the
use of persistent pesticides. After the 1972 U.S. DDT ban, populations rebounded, and the Osprey became a conservation success symbol. Ospreys are still listed as endangered or threatened in some states—especially inland, where pesticides decimated or extirpated many populations. As natural nest sites have succumbed to tree removal and shoreline development, specially constructed nest platforms and other structures, such as channel markers and utility poles, have become vital to the Osprey’s
recovery. Sadly, a growing cause of death for Ospreys is entanglement at the nest. Adults incorporate baling twine and other discarded plastic lines into their nests, and these can wrap around a chick's feet and injure it or keep it from leaving the nest.
Trở lại đầu trangTín dụng
Dunne, P. [2006].Người bạn đồng hành hướng dẫn lĩnh vực thiết yếu của Pete Dunne.Houghton Mifflin Harcourt, New York, Hoa Kỳ.
Lutmerding, J. A. và A. S. Tình yêu.[2020].Hồ sơ tuổi thọ của các loài chim Bắc Mỹ.Phiên bản 2020. Trung tâm nghiên cứu động vật hoang dã Patuxent, Phòng thí nghiệm Bird Banding 2020.
Đối tác trong chuyến bay.[2020].Cơ sở dữ liệu đánh giá bảo tồn gia cầm, phiên bản 2020.
Poole, A. F., R. O. Bierregaard và M. S. Martell.2002. Osprey [Pandion Haliaetus].Trong các loài chim của Bắc Mỹ, số 683 [A. Poole và F. Gill, biên tập.].Những con chim của Bắc Mỹ, Inc., Philadelphia, PA.
Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon và W. A. Link [2019].Cuộc khảo sát, kết quả và phân tích chim nhân giống Bắc Mỹ 1966 19662019.Phiên bản 2.07.2019.Trung tâm nghiên cứu động vật hoang dã USGS Patuxent, Laurel, MD, Hoa Kỳ.
Sibley, D. A. [2014].Hướng dẫn Sibley về chim, phiên bản thứ hai.Alfred A. Knopf, New York, NY, Hoa Kỳ.
Trở lại đầu trang
Ospreys là bất thường giữa những con diều hâu trong việc sở hữu một ngón chân ngoài có thể đảo ngược cho phép chúng nắm bắt với hai ngón chân ở phía trước và hai phía sau.Món đệm có gai trên lòng bàn chân của chim giúp chúng kẹp cá trơn.Khi bay với con mồi, một con chim ưng xếp lên đầu bắt đầu trước để có khả năng chống gió ít hơn.possessing a reversible outer toe that allows them to grasp with two toes in front and two behind. Barbed pads on the soles of the birds' feet help them grip slippery fish. When flying with prey, an Osprey lines up its catch head first for less wind resistance.
Vào đầu mùa sinh sản, con đực thực hiện một điệu nhảy bầu trời trên không, đôi khi được gọi là Fish Fish-Flight.Với đôi chân lơ lửng, thường kẹp một con cá hoặc vật liệu làm tổ trong móng vuốt của mình, con đực xen kẽ những khoảng thời gian lơ lửng với những con nhầm nước chậm, nông cao tới 600 feet trở lên so với khu vực tổ.600 feet or more above the nest site.
Tuổi thọ điển hình là 7 trận10 năm, mặc dù hiếm khi các cá nhân có thể phát triển đến 20 tuổi25.Osprey hoang dã châu Âu lâu đời nhất được ghi nhận đã sống trên ba mươi tuổi.7–10 years, though rarely individuals can grow to as old as 20–25 years. The oldest European wild osprey on record lived to be over thirty years of age.