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Osprey
Pandion haliaetus

Fish Eagle/Hawk, Lang Siput/Tiram (Malay)

The Osprey is a unique bird, the only member of its genus. It is believed that Ospreys followed a different evolutionary path quite early on, so that they are quite different from other raptors.

Ospreys usually forage on the wing, although some may perch-and-wait. They often hover, but may also glide or circle to look for prey. Once the prey is located, they dive, sometimes from a great height, entering the water feet first. They may take off straightaway or lie on the water and rest for a while. More rarely, they snatch prey by skimming the water. To fly more smoothly after catching a fish, the bird will re-arrange the fish in its talons so the fish faces head first, thus presenting a more streamlined profile.

Ospreys eat mainly live fish. Although they are not above eating any dead fish they come across, they are not scavengers. They occasionally also take other small prey such as snakes, rodents, other aquatic prey and even other birds.
Mangrove and wetland wildlife at
Sungei Buloh Nature Park
Main features: Large (54-64cm); wings long narrow; tail short dark faintly banded. White head, crest with eye-stripe broad black; underparts white with breast band brownish; upperparts dark brown; bill black; feet grey.

Females: Brown spots on the chest like a necklace; larger, heavier.
osprey in flight
Photo from Strange
and Jeyarajasingam
Juvenile: Upperparts and wings light brown edged with buff, breast band broader.

Call: Usually a quiet bird, but may make loud piercing whistles tiong.

In flight: Narrow wings held kinked at carpals giving a droopy appearance, when soaring wings shallowly arched. Wing beats shallow and rapid. From below: white underwing contrasting with black carpal patch and flight feathers blackish; undertail has 5 black bands, broadest at tip.

Status in Singapore: Common winter visitor throughout, including North and South offshore islands.

World distribution: Worldwide, except Antarctica.

Classification: Family Accipitridae. World 240 species, Singapore 27 species.
Like other raptors, Ospreys have strong hooked talons and beaks. But Ospreys have additional unique adaptations. Their feet have two toes pointing backwards (most birds only have at most one toe facing backwards), and the underside of their feet are covered with especially rough, short spines to provide a firm grip. Their feathers are also very oily for extra waterproofing as they plunge into the water. However, this makes them buoyant, so they cannot go deeper than 1m below the surface. Their nostrils can close as they dive underwater.

Ospreys usually hunt in the early morning or late afternoon perhaps because the light is best for sighting underwater prey. They rarely hunt over open sea, preferring to focus on calm shallow waters with trees or structures to provide perches (trees, poles). Favourite haunts include estuaries, mangroves, freshwater wetlands and man-made habitats such as reservoirs, rice fields, irrigation canals. They avoid mountainous regions.

Ospreys are solitary creatures, hunting and even migrating alone. But where fishing is good, several can coexist peacefully.

Breeding: Ospreys do not breed in our part of the world. They generally pair for life. The male selects the nesting site, which ideally should be located near a good source of food (3-5 km from shallow water), free of predators (e.g., near or over water, on islands) and surrounded by open area for easy take off and landing and easy sight approaching of predators. Sites are usually tall dead trees with flat tops or even man-made structures such as pylons and towers (3-18m off the ground); sometimes also on cliffs. Some ospreys nest in colonies.

The male courts with aerial acrobatics and by presenting his mate with food or nesting material, accompanied by a courtship call. The male will feed the female even before she lays and often throughout the rest of the breeding season, while the female stays in the nest to look after the young and fend off predators. How well the male feeds the female determines the strength of the pair bond.

The nest is a platform of coarse sticks, other bits and pieces. It is reused every season. Both parents build or refurbish the nest. 2-4, usually 3, creamy eggs with reddish-brown spots are laid. But there is sibling rivalry among the young so it is rare for more than 1-2 offspring to survive. The female does most of the incubation, which takes about 5-6 weeks, relying on the male to feed her. Although both parents feed the young, the males take the lead, often eating the head and tail only, leaving the more nutritious parts of the fish for his mate and their young. The young fledge in about 6 weeks. Ospreys are able to breed at 3-5 years old and can live for 13-18 years.

Migration: One population of Osprey breeds in the north in a circle covering Russia, North America and Europe. While those that breed far north migrate to the subtropics and tropics in winter, others are resident in northern subtropical regions (e.g., Florida) and breed in winter (December-January, the babies fledge in April-May). Ospreys seen in Singapore are northern breeders; which arrive mainly in October-March. Ospreys, however, can be seen year-round in Singapore. These are probably immatures or non-breeders who stayed over. Another Osprey population breeds in the south, in Australia and eastern Indonesia. These lack the masks of the northern population and winter in the Philippines and possibly Borneo. Ospreys migration in flocks of 8-10.

Status and threats: As a top predator, Ospreys are considered a good indicator of the health of their environment. Ospreys were widely hunted as a pest on game fishing and fish farms (in reality, their catch is negligible; Ospreys can only eat about 300gm at one sitting and will stop hunting once they have their fill). Hunting them is now illegal in many parts of their distribution. Habitat destruction also removes suitable nesting sites and prey. Pesticide poisoning of prey (e.g., DDT) not only reduced the number of prey but also weakens their egg shells and makes the eggs less permeable to oxygen and causes the eggs to break as the parents incubate them. Efforts to conserve Ospreys include building special nesting platforms for them.


LINKS REFERENCES
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  • Morten Strange, "A Photographic Guide to Birds of Malaysia and Singapore: including Southeast Asia, the Philippines and Borneo", Periplus, 2000 (p. 70: description, voice, habits, distribution, status, photo).
  • David R Wells, "The Birds of the Thai-Malay Peninsula: Vol. 1 (Non-Passarines)", Academic Press, 1999 (p. 121-122: identification, distribution map, habits, habitat, migration, conservation).
  • Lim Kim Seng, "Pocket Checklist of the Birds of the Republic of Singapore", Nature Society (Singapore), 1999 (Abundance, status, Chinese and Malay names).
  • Lim Kim Seng and Dana Gardner, "Birds: An Illustrated Field Guide to the Birds of Singapore", Sun Tree Publishing Ltd., 1997 (p. 71: identification, status in Singapore, distribution, diagram, number of species).
  • G W H Davison and Chew Yen Fook, "A Photographic Guide to Birds of Peninsular Malaysia and Singapore", New Holland Publishers Ltd., 1995 (p. 22: identification, status in Singapore, distribution, photo).
  • Morten Strange and Allen Jeyarajasingam, "Birds: A Photographic Guide to the Birds of Peninsular Malaysia and Singapore", Sun Tree Publishing, 1993 (p. 113: description, distribution, habits, habitat, photo).
  • Clive Briffett, "A Guide to the Common Birds of Singapore", BP Science Centre,1992 (p. 49,50: identification, habits, habitat).
  • Christopher Hails, "Birds of Singapore" illustrated by Frank Jarvis, Times Editions, 1987 reprinted 1995 (p. 58: habits, description, status in Singapore, and lovely drawings of the birds).
  • G C Madoc, "An Introduction to Malayan Birds", Malayan Nature Society, 1947 (p. 64: description, habits, habitat).
  • Sir John A S Bucknill and E N Chasen, " Birds of Singapore and South-East Asia", Tynron Press, 1927, edition 1990 (p. 103: field notes on habits).
  • Dr. Harold G Cogger (et. al), "Encyclopedia of Animals"; Raptors by Penny Olsen, Weldon Owen, 1993 (p. 296: snippets).
 
By Ria Tan, 2001