|Australian Bush Birds|
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|Eastern Osprey - Pandion cristatus|
|Eastern Osprey at Broome, Western Australia|
The Eastern Osprey - Pandion cristatus - is a large hawk with long angular wings, heavy feet and long forearms. The wings are tapered like a large seabird; wing tips extend beyond the tail tip at rest. Adult has dark brown upper parts with white head and under parts; there is a dark streak through the eye and down the side of neck. A mottled brown breast band is narrow and faint in males and heavy in females. Legs are white. Underwing faintly barred, outermost flight feathers have black tips, underside is white, tail barred. Brown barring on the long, tapering wings, widest at the body, slightly kinked when soaring. Cere (above the beak) is grey, eyes pale yellow to orange-yellow, feet pale grey.
Grows 50 to 65 centimetres long with wingspan of 149 to 168 centimetres, females are larger.
Juveniles are similar to adults but rustier in colour, crown and nape are more streaked; under parts are spotted cream, breast-band is broad and heavy, eyes orange-yellow to orange.
Found around the Australian mainland except for Victoria and south-east South Australia, not found in Tasmania. In practice it is uncommon to rare or absent from closely settled parts of south-east Australia
Lives mainly in coastal waters and estuaries, beaches, islets and reefs; usually not far out to sea except on islets or exposed reefs. Follows major rivers and wetlands far inland from the coast; even to arid regions where large pools occur in gorges hundreds of kilometres inland. Hunts singly or in dispersed pairs along a feeding and breeding territory along five to 20 kilometres of coastline. A hunting osprey may soar high to spot schools of fish, then glide down folding the wings before plunging feet-first into the sea. In Australia Ospreys are a marine species, some overseas species hunt in fresh water.
Ospreys have dense plumage to reduce wetting when plunge-diving and a large oil-gland for waterproofing while preening. Flexible joints allow them to sweep the wings clear of the water and so take off almost vertically
Ospreys eat fish up to two kilograms and occasionally sea snakes. To take a fish, the Osprey plunges into water with the feet forward, submerging in a plume of spray with the wings raised. About 90 per cent of dives are successful and the bird emerges from the water with a fish in its talons aligned fore-and-aft - one description succintly describes the fish as slung "torpedo-fashion". One foot holds the fish near the head and the trailing foot grips the rear of the fish held with the head forward in the direction of flight. Reversible outer toes and rough surfaces permit the Osprey to grip slippery fish.
|Eastern Osprey - page 2|
|Eastern Osprey soaring at Brunswick Heads, New South Wales. Breast marking indicate this is a female.|
The fish is carried to a prominent perch or to the nest which is used as a feeding platform outside the breeding season.
Unlike the White-bellied Sea-Eagle, the Osprey readily submerges to at least 1 metre to get fish. At other times it snatches fish close to the surface while in flight immersing only the legs.
Builds large nests on prominent headlands, trees and communications towers. Nests are never in colonies in Australia. Breeding takes place from May to October in the south and April to July in the north. The nest is a large bowl of sticks and driftwood up to two metres across and two metres deep. The resident pair adds to the nest each year and while nesting. The nest is roughly lined with grass and seaweed. Male and female share nest building and repair. He brings the material while the female works it into the nest which can be up to 30 metres high on a rocky foreshore, on an island, on rocky cliff faces, in trees or on transmission towers. Some local authorities establish prominent nest platforms for Ospreys.
|Eastern Osprey on an artificial nesting platform at Pottsville, New South Wales. The resident pair add more sticks each year between seasons as well as while nesting.|
|Eastern Osprey - page 3|
Aerial displays are a conspicuous part of the breeding ritual involving spectacular diving and swooping at heights of 100 to 300 metres above the nest. The pair flies upward, the male hovers briefly at the top, then both plunge downward with wings closed and tail spread. They may also soar together, the male chasing the female.
Two or three, occasionally four eggs are laid; matt white to buff brown blotched with chocolate to purple-brown, sometimes with underlying purple-grey; oval, about 60 by 44 millimetres. Incubation mostly by the female, in about five weeks. The male feeds the female during incubation bringing her one to two fish per day.
Young birds do not grow feathers through their down for 30 days; until then the female looks after, and shades, them. She does all the brooding and feeding while the male does all the fishing, up to 3 to 5 fish a day depending on brood size. The female tears up fish delivered by the male and passes pieces to the young; up to ten pieces a minute have been recorded. Young remain dependant on their parents for two to three months after fledging; some then disperse widely (going up to 700 kilometres away), others remain around the parental territory until the next season then become breeding adults themselves.
The oldest banded bird recovered was alive 11 years after banding.
¶ Genus Pandion is in Family Accipitridae with the Sea-Eagle, Kites, Hawks, Harriers and Eagles.
¶ DNA studies, combined with small, but consistent, difference in plumage and morphology have led to recognising three Osprey species around the world. The Australian version is no longer a subspecies of Pandion haliaetus but is now a separate species:- Pandion cristatus.