White-bellied Sea Eagles
The White-bellied Sea Eagles (Haliaeetus leucogaster) also known as the White-bellied Fish-Eagle or White-breasted Sea Eagle, is a large bird of prey in the family Accipitridae.
Overview
It is closely related to other eagles, kites, hawks, harriers, and Old World vultures.
It is resident from India through southeast Asia to Australia on coasts and major waterways.
It is a distinctive bird. The adult has a white head, breast, under-wing coverts and tail. The upper parts are grey and the black under-wing flight feathers contrast with the white coverts. The tail is short and wedge-shaped as in all Haliaeetus species.
Distribution / Range
The White-bellied Sea-eagles are found from India and Sri Lanka, through all of coastal Southeast Asia including Burma, Thailand, Malaysia, Indonesia, Indochina, the Philippines and southern China including Hong Kong, and into New Guinea and northeast to the Bismarck Archipelago, and Australia. In the north Solomons, it is restricted to Nissan Island, and replaced elsewhere by Sanford’s Sea-eagle.
They are a common sight in coastal areas, but may also be seen well inland.
Birds are often seen perched high in a tree or soaring over waterways and adjacent land.
Birds form permanent pairs that inhabit territories throughout the year.
Description
The White-bellied sea eagle is one of the largest raptors in Southeast Asia, and the second largest bird of prey in Australia after the Wedge-tailed Eagle (Aquila audax) which stands up to 1 m.
The sea eagle is white on the head, rump, and underparts and dark grey on the 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 lead blue-grey with a darker tip, and the eye is dark brown. The cere is also lead grey. The legs and feet are yellow or grey, with long black talons (claws).
Males and females look alike. Males are 70–80 cm (28–32 in) and weigh 1.8–3 kg (4–6.6 lb). Females are slightly larger, at 80–90 cm (32–36 in) and 2.5–4.5 kg (5.5–10 lb). The wingspan ranges from 1.8 to 2.2 m (6–7 ft).
Young sea eagles in their first year are predominantly brown. Their plumage becomes more infiltrated with white until they acquire the complete adult plumage by their fourth or fifth year.
They soar on thermals holding their wings in a ‘V’ shape, unlike other raptors who hold them horizontally.
Calls / Vocalizations
The loud “goose-like” honking call is a familiar sound, particularly during the breeding season; pairs often honk in unison.
Diet / Feeding
They feed on fish and sea snakes, which they catch by skimming over the water and catching their prey with their talons. They do not dive underwater, however. They keep within 1 km of shores, as there are no thermals over water.
The White-bellied sea eagle hunts mainly aquatic animals, such as fish, turtles, and sea snakes, but it takes birds, such as Little Penguins, coots, and shearwaters, and mammals as well.
In the Bismarck Archipelago, it has been reported feeding on various species of possum. It is a skilled hunter and will attack prey up to the size of a swan. They also feed on carrion such as dead sheep, birds, and fish along the waterline, and may even raid fishing nets. They harass smaller birds such as Swamp Harriers, forcing them to drop any food that they are carrying.
Sea eagles feed alone, in pairs, or family groups.
Nesting / Breeding
The breeding season varies according to location—it has been recorded in the dry season in the Trans-Fly and Central Province of Papua New Guinea, and from June to August in Australia.
They chose the tallest tree to nest, and even sometimes man-made pylons. The nest is a large deep bowl constructed of sticks and branches, and generally sited in large trees overlooking bodies of water. Cliffs are also suitable nesting sites, while those nests built directly on the ground are located on islands. Normally two oval dull white eggs are laid, although one is often ejected or broken. They measure 73 x 55 mm.
Conservation status
The White-bellied Sea-eagles are listed as least concern by the IUCN. There are an estimated 10 to 100 thousand individuals, although there seems to be a decline in numbers.
Australia
White-bellied Sea-eagles are listed as marine and migratory under the Australian Environment Protection and Biodiversity Conservation Act 1999.
State of Victoria, Australia
- The White-bellied sea eagle is listed as threatened on the Victorian Flora and Fauna Guarantee Act (1988). Under this Act, an Action Statement for the recovery and future management of this species has been prepared.
- On the 2007 advisory list of threatened vertebrate fauna in Victoria, the White-bellied sea eagle is listed as vulnerable.
Cultural significance
Known as Manulab to the people of Nissan Island, the White-bellied Sea Eagle is considered special and forbidden to be killed.
Its calls at night are said to foretell danger, and seeing a group of eagles flying overhead calling is a sign that someone has died.
A local Sydney name was Gulbi, and the bird was the totem of the late 18th century indigenous leader Colebee, of the Cadigal people.
A Malay name is burung hamba “slave of the shellfish”, Malay tales told of the sea eagle screaming at the turning of tides to warn the shellfish. The White-bellied sea eagle is also the emblem of the state of Selangor.
It is also featured on the $10,000 Singapore note.
Taxonomy
The White-bellied Sea Eagle was first described by the German naturalist Johann Friedrich Gmelin in 1788.
Its species name is derived from the Ancient Greek leuko- ‘white’ and gaster ‘belly’. Its closest relative is the little-known Sanford’s Sea-eagle of the Solomon Islands. These form a species pair, and as usual in sea eagle species pairs, as opposed to the dark-headed Sanford’s, the White-bellied sea eagle has a white head.
Talons, bills, and eyes are dark as in all Gondwanan sea eagles. This species pair has at every age at least some dark colouration in its tail, though this may not always be visible in this species.
Although they differ much in appearance and ecology, their ancestors diverged less than one million years ago, the “2%” value used is too low, as the authors remark, possibly by nearly an order of magnitude.
