Widespread, Spectacular, Fish eaters… Ospreys

By Keith Hutton on July 19, 2012 in Other

Ospreys are birds of prey that occur as migrants, winter visitors or breeding birds in all continents of the world except Antarctica. Until recently it was accepted that the same single species was present worldwide. However, DNA analyses published within the last 10 years suggest there are in fact three very similar but distinct species. The Eastern Osprey occurs in Australia, Indonesia, PNG, Solomon Islands and New Caledonia, a second species occurs in North, Central and South America, and the other ranges across Europe and Asia.

An adult osprey is a graceful fish hawk with a white head and underparts, brown back and wings, and a relatively short brown tail. The head appears small and prominent, particularly in flight. Ospreys have a bold dark mark through the eye and down the neck; a broad brown necklace is most obvious in female and juvenile birds, less so in adult males. Juveniles are generally similar to adults but with buff white feather tips. Ospreys are usually seen singly, or in pairs and family groups patrolling over open water with long, arched wings, and often perched on dead branches or other good vantage points.

Ospreys in Australia are most common on northern coasts and islands, moderately common in the southwest, thinly scattered elsewhere and uncommon to rare on southeast and southern coasts. Beaches, tidal sand flats and mud flats, estuaries, mangroves, harbours and coastal islands are preferred habitats. In the Sydney region, ospreys recently nested successfully at Narrabeen and have been regularly seen south of Sydney for nearly 30 years. They have recently attempted to breed near Ulladulla on the NSW south coast too. I’d not heard of any in the Eastern Suburbs before, but there were two hanging around Bronte a couple of months back, in the week after Easter. They were seen flying close to the shore about 30 – 50 metres above the ocean, moving south towards Maroubra, mobbed by a couple of magpies, before turning around and heading back north towards Bondi.

Ospreys feed almost exclusively on fish and occasional small birds, reptiles and crustaceans. They hunt over clear water on angled bowed wings, regularly hovering until they come across suitable prey, then plunging spectacularly from 10 – 50 metres, feet first into the water. When they emerge with a fish in their talons they shake off the excess water in flight and carry their prey, with its head pointing forward like a torpedo, to a perch close by, where they select small pieces to eat rather than swallowing it whole.

Ospreys in Australia are generally considered sedentary but immature birds are known to be dispersive after they leave their parents. At such times they have been seen well inland along major rivers, more commonly in the north of the country. This behaviour is probably responsible for most of the observations around Sydney and on the NSW south coast. There is no evidence of recent population changes in Australia where ospreys appear to be doing pretty well and may be expanding their breeding range. Over one hundred pairs nest in NSW and most of these are still located close to the coast in the north of the state.