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 a superspecies.

A distinctive bird, the adult white-bellied sea eagle has a white head, breast, under-wing coverts and tail.

Like many raptors, the female is larger than the male, and can measure up to 90 cm (35 in) long with a wingspan of up to 2.2 m (7.2 ft), and weigh 4.5 kg (9.9 lb).

Resident from India and Sri Lanka through Southeast Asia to Australia on coasts and major waterways, the white-bellied sea eagle breeds and hunts near water, and fish form around half of its diet.

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 was formally described by the German naturalist Johann Friedrich Gmelin in 1788 under the binomial name Falco leucogaster.

[3] Gmelin based his account on the "white-bellied eagle" that had been described in 1781 by John Latham from a specimen in the Leverian collection that had been obtained in February 1780 at Princes Island off the westernmost cape of Java during Captain Cook's last voyage.

The study authors conclude that although the genetic divergence is more consistent with subspecies, the distinctness in appearance and behaviour warrants the two being retained as separate species.

For active flight, the white-bellied sea eagle alternates strong deep wing-beats with short periods of gliding.

[20] A young white-bellied sea eagle in its first year is predominantly brown,[16] with pale cream-streaked plumage on their head, neck, nape and rump areas.

They might also be confused with the black-breasted buzzard (Hamirostra melanosternon), but this species is much smaller, has white patches on the wings, and has a more undulating flight.

[28] The white-bellied sea eagle is found regularly from Mumbai (sometimes north to Gujarat,[29] and in the past in the Lakshadweep Islands) eastwards in India,[30][31] Bangladesh, and Sri Lanka in southern Asia, through all of coastal Southeast Asia including Burma, Thailand, Malaysia, Indonesia, Indochina,[24] the main and offshore islands of the Philippines,[28] and southern China including Hong Kong,[24] Hainan and Fuzhou,[15] eastwards through New Guinea and the Bismarck Archipelago,[32] and Australia.

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.

[46] A pair of white-bellied sea eagles performs skillful displays of flying before copulation: diving, gliding, and chasing each other while calling loudly.

[26] Often, locations are sought where there is a tall dead tree or high branch with good visibility which can be used as a perch to survey the surrounding area,[26] which is generally a low-lying locale near water with some forest cover.

[44] The white-bellied sea eagle is an opportunistic carnivore and consumes a wide variety of animal prey, including carrion.

[42] The white-bellied sea eagle may also dive at a 45-degree angle from its perch and briefly submerge to catch fish near the water surface.

The white-bellied sea eagle attacks these birds by striking them with outstretched talons from above or by flying upside down underneath the smaller predator and snatching the prey, all the while screeching shrilly.

Wedge-tailed eagles took rabbits, various macropods, terrestrial birds such as cockatoos and parrots, and various passerines including magpies and starlings.

White-bellied sea eagles caught fish, water-dwelling reptiles such as the eastern long-necked turtle and Australian water dragon, and waterbirds such as ducks, grebes and coots.

[66] Elsewhere, the clearing of trees suitable for nesting has seen it largely disappear locally, such as the removal of stands of Casuarina equisetifolia in Visakhapatnam district in Andhra Pradesh in India.

[72] DDT was a widely used pesticide in agriculture that was found to have significant adverse effects on wildlife, particularly egg thinning and subsequent breakage in birds of prey.

The white-bellied sea eagle was one of the more affected species, probably due to its feeding in areas heavily treated with pesticide such as swamps.

However, there may have been an increase in population inland, secondary to the creation of reservoirs, dams and weirs, and the spread of the introduced common carp (Cyprinus carpio).

[41] It is also listed as Threatened under Victoria's Flora and Fauna Guarantee Act (1988), with possibly fewer than 100 breeding pairs remaining in the state.

[75] white-bellied sea eagles have been observed to increase their hunting ranges to include salmon fish farms, but the effect of this on breeding success is unknown.

[14] A local Sydney name was gulbi, and the bird was the totem of Colebee, the late 18th century indigenous leader of the Cadigal people.

[83] Called Kaulo in the recently extinct Aka-Bo language, the white-bellied sea eagle was held to be the ancestor of all birds in one Andaman Islands folk tale.

[83] Malay magnate Loke Wan Tho had a 40-metre-high (130 ft) tower built for the sole purpose of observing a white-bellied sea eagle nest in the palace gardens of Istana Bukit Serene in Johor Bahru.

[88] From 2010, a nesting pair of white-bellied sea eagles have had their attempts at raising chicks filmed live on "EagleCam", with footage on display at the nearby Birds Australia Discovery Centre in Sydney Olympic Park, New South Wales.