The White-bellied sea eagle (Haliaeetus leucogaster) is a large diurnal bird of prey. Originally described by Johann Friedrich Gmelin in 1788, it is closely related to Sanford's sea eagle of the Solomon Islands, and the two are considered superspecies. The White-bellied sea eagle is revered by indigenous people in many parts of Australia, and is the subject of various folk tales throughout its range.
The White-bellied sea eagle has a white head, rump and underparts, and dark or slate-grey back and wings. In flight, the black flight feathers on the wings are easily seen when the bird is viewed from below. The large, hooked bill is a leaden blue-grey with a darker tip, and the irides are dark brown. The cere is also lead grey. The legs and feet are yellow or grey, with long black talons (claws). Unlike those of eagles of the genus Aquila, the legs are not feathered. The sexes are similar but like many raptors, the female is larger than the male. A young White-bellied sea eagle in its first year is predominantly brown, with pale cream-streaked plumage on their head, neck, nape, and rump areas. The plumage becomes more infiltrated with white until it acquires the complete adult plumage by the fourth or fifth year.
White-bellied sea eagles are found regularly from Mumbai eastwards in India, Bangladesh, and Sri Lanka in southern Asia, through all of coastal Southeast Asia including Burma, Thailand, Malaysia, Indonesia, Indochina, the main and offshore islands of the Philippines, and southern China including Hong Kong, Hainan, and Fuzhou, eastwards through New Guinea and the Bismarck Archipelago, and Australia. In the northern Solomons, they are restricted to Nissan Island. These birds occur mainly in coastal areas, islands, and estuaries but also in large inland water bodies, lakes, rivers, and wetlands. They usually breed near the water with some forest cover or in rocky areas.
White-bellied sea eagles are generally territorial; some birds form permanent pairs that inhabit territories throughout the year, while others are nomadic. Immature birds are generally dispersive, with many moving over 50 km (31 mi) away from the area they were raised. These birds are diurnal and often seen perched high in a tree or soaring over waterways and adjacent land. They spend time singly or in pairs. Small groups of White-bellied sea eagles sometimes gather if there is a plentiful source of food such as a carcass or fish offal on a ship. A pair may cooperate to hunt. During hunting the bird prepares for the strike by holding its feet far forward (almost under its chin) and then strikes backward while simultaneously beating its wings to lift upwards. They often catch a fish by flying low over the water and grasping it in its talons. Generally, only one foot is used to seize prey. White-bellied sea eagles may also dive at a 45-degree angle from their perch and briefly submerge to catch fish near the water's surface. These large birds of prey have a loud goose-like honking call which is heard particularly during the breeding season; pairs often honk in unison and often carry on for some time when perched. The male's call is higher-pitched and more rapid than that of the female.
