The osprey (/ˈɒspri, -preɪ/;[2] Pandion haliaetus), historically known as sea hawk, river hawk, and fish hawk, is a diurnal, fish-eating bird of prey with a cosmopolitan range. It is a large raptor, reaching more than 60 cm (24 in) in length and 180 cm (71 in) across the wings. It is brown on the upperparts and predominantly greyish on the head and underparts.
The osprey tolerates a wide variety of habitats, nesting in any location near a body of water providing an adequate food supply. It is found on all continents except Antarctica, although in South America it occurs only as a non-breeding migrant.
As its other common names suggest, the osprey's diet consists almost exclusively of fish. It possesses specialised physical characteristics and unique behaviour in hunting its prey. Because of its unique characteristics it is classified in its own taxonomic genus, Pandion, and family, Pandionidae.
The osprey was described in 1758 by the Swedish naturalist Carl Linnaeus under the name Falco haliaetus in his landmark tenth edition of his Systema Naturae.[3][4] Linnaeus specified the type locality as Europe, but in 1761 he restricted the locality to Sweden.[4][5] The osprey is the only species placed in the genus Pandion that was introduced by the French zoologist Marie Jules César Savigny in 1809.[6][7] The genus is the sole member of the family Pandionidae.[7] The species has always presented a riddle to taxonomists, but here it is treated as the sole living member of the family Pandionidae, and the family listed in its traditional place as part of the order Accipitriformes. Other schemes place it alongside the hawks and eagles in the family Accipitridae.[4] The Sibley-Ahlquist taxonomy has placed it together with the other diurnal raptors in a greatly enlarged Ciconiiformes, but this results in an unnatural paraphyletic classification.[8] Molecular phylogenetic analysis has found that the family Pandionidae is sister to the family Accipitridae. It is estimated that the two families diverged around 50.8 million years ago.[9]
The osprey is unusual in that it is a sole living species that occurs nearly worldwide. Even the few subspecies are not unequivocally separable. There are four generally recognised subspecies, although differences are small, and ITIS lists only the first three.[10]
Two extinct species were named from the fossil record.[16] Pandion homalopteron described by Stuart L. Warter in 1976 was found in marine Middle Miocene deposits of the Barstovian age in the southern part of California. The second species Pandion lovensis was described by Jonathan J. Becker in 1985 and found in Florida; it dates to the Late Clarendonian and possibly represents a separate lineage from that of P. homalopteron and P. haliaetus. A number of claw fossils have been recovered from Pliocene and Pleistocene sediments in Florida and South Carolina.[citation needed]
The oldest recognized family Pandionidae fossils were recovered from the Oligocene age Jebel Qatrani Formation in Faiyum Governorate, Egypt. However, they are not complete enough to assign to a specific genus.[17] Another Pandionidae claw fossil was recovered from Early Oligocene deposits in the Mainz basin, Germany, and was described in 2006 by Gerald Mayr.[18]
The genus name Pandion derives from Pandíōn Πανδίων, the mythical Greek king of Athens and grandfather of Theseus, Pandion II. The species name haliaetus (Latin: haliaeetus)[19] comes from Greek ἁλιάετος haliáetos "sea-eagle" (also ἁλιαίετος haliaietos) from the combining form ἁλι- hali- of ἅλς hals "sea" and ἀετός aetos, "eagle".[20][21]
The origins of osprey are obscure;[22] the word itself was first recorded around 1460, derived via the Anglo-French ospriet and the Medieval Latin avis prede "bird of prey," from the Latin avis praedae though the Oxford English Dictionary notes a connection with the Latin ossifraga or "bone breaker" of Pliny the Elder.[23][24] However, this term referred to the bearded vulture.[25]
The osprey differs in several respects from other diurnal birds of prey. Its toes are of equal length, its tarsi are reticulate, and its talons are rounded, rather than grooved. The osprey and owls are the only raptors whose outer toe is reversible, allowing them to grasp their prey with two toes in front and two behind. This is particularly helpful when they grab slippery fish.[26]The osprey is 0.9–2.1 kg (2.0–4.6 lb) in weight and 50–66 cm (20–26 in) in length with a 127–180 cm (50–71 in) wingspan. It is, thus, of similar size to the largest members of the Buteo or Falco genera. The subspecies are fairly close in size, with the nominate subspecies averaging 1.53 kg (3.4 lb), P. h. carolinensis averaging 1.7 kg (3.7 lb) and P. h. cristatus averaging 1.25 kg (2.8 lb). The wing chord measures 38 to 52 cm (15 to 20 in), the tail measures 16.5 to 24 cm (6.5 to 9.4 in) and the tarsus is 5.2–6.6 cm (2.0–2.6 in).[27][28]
The upperparts are a deep, glossy brown, while the breast is white, sometimes streaked with brown, and the underparts are pure white. The head is white with a dark mask across the eyes, reaching to the sides of the neck.[29] The irises of the eyes are golden to brown, and the transparent nictitating membrane is pale blue. The bill is black, with a blue cere, and the feet are white with black talons.[26] On the underside of the wings the wrists are black, which serves as a field mark.[30] A short tail and long, narrow wings with four long, finger-like feathers, and a shorter fifth, give it a very distinctive appearance.[31]
The sexes appear fairly similar, but the adult male can be distinguished from the female by its slimmer body and narrower wings. The breast band of the male is also weaker than that of the female or is non-existent, and the underwing coverts of the male are more uniformly pale. It is straightforward to determine the sex in a breeding pair, but harder with individual birds.[31]
The juvenile osprey may be identified by buff fringes to the plumage of the upperparts, a buff tone to the underparts, and streaked feathers on the head. During spring, barring on the underwings and flight feathers is a better indicator of a young bird, due to wear on the upperparts.[29]
In flight, the osprey has arched wings and drooping "hands", giving it a gull-like appearance. The call is a series of sharp whistles, described as cheep, cheep, or yewk, yewk. If disturbed by activity near the nest, the call is a frenzied cheereek![32]
The osprey is the second most widely distributed raptor species, after the peregrine falcon, and is one of only six land-birds with a worldwide distribution.[33] It is found in temperate and tropical regions of all continents, except Antarctica. In North America it breeds from Alaska and Newfoundland south to the Gulf Coast and Florida, wintering further south from the southern United States through to Argentina.[34] It is found in summer throughout Europe north into Ireland, Scandinavia, Finland and Great Britain though not Iceland, and winters in North Africa.[35] In Australia it is mainly sedentary and found patchily around the coastline, though it is a non-breeding visitor to eastern Victoria and Tasmania.[36]
There is a 1,000 km (620 mi) gap, corresponding with the coast of the Nullarbor Plain, between its westernmost breeding site in South Australia and the nearest breeding sites to the west in Western Australia.[37] In the islands of the Pacific it is found in the Bismarck Islands, Solomon Islands and New Caledonia, and fossil remains of adults and juveniles have been found in Tonga, where it probably was wiped out by arriving humans.[38] It is possible it may once have ranged across Vanuatu and Fiji as well. It is an uncommon to fairly common winter visitor to all parts of South Asia,[39] and Southeast Asia from Myanmar through to
