The
White-bellied Sea Eagle (
Haliaeetus leucogaster), also known as the
White-breasted Sea Eagle, is a large diurnal
bird of preyBirds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....
in the family
AccipitridaeThe Accipitridae, one of the two major families within the order Accipitriformes , are a family of small to large birds with strongly hooked bills and variable morphology based on diet. They feed on a range of prey items from insects to medium-sized mammals, with a number feeding on carrion and a...
. Originally described by
Johann Friedrich GmelinJohann Friedrich Gmelin was a German naturalist, botanist, entomologist, herpetologist and malacologist.- Education :Johann Friedrich Gmelin was born as the eldest son of Philipp Friedrich Gmelin in 1748 in Tübingen...
in 1788, it is closely related to Sanford's Sea Eagle of the
Solomon IslandsSolomon Islands is a sovereign state in Oceania, east of Papua New Guinea, consisting of nearly one thousand islands. It covers a land mass of . The capital, Honiara, is located on the island of Guadalcanal...
, and the two are considered a
superspeciesA superspecies is a group of at least two more or less distinctive species with approximately parapatric distributions. Not all species complexes, whether cryptices or ring species are superspecies, and vice versa, but many are...
. A distinctive bird, the adult White-bellied Sea Eagle has a white head, breast, under-wing
covertsA covert feather on a bird is one of a set of feathers, called coverts, which as the name implies, cover other feathers. The coverts help to smooth airflow over the wings and tail.- 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
HaliaeetusSea eagle mainly refers to Sea eagle, birds of prey of the genus Haliaeetus.It may also refer to:-Aerospace:* Sea Eagle , British, anti-ship missile* Sea Eagle * Supermarine Sea Eagle, 1920s British passenger flying boat-Sports:...
speciesIn biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
. Like many raptors, the female is slightly larger than the male, and can measure up to 90 cm (36 in) long with a wingspan of up to 2.2 m (7 ft), and weigh 4.5 kg (10 lb). Immature birds have brown
plumagePlumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...
, which is gradually replaced by white until the age of five or six years. The call is a loud goose-like honking.
Resident from
IndiaIndia , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
and
Sri LankaSri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
through
southeast AsiaSoutheast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
to
AustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
on coasts and major waterways, the White-bellied Sea Eagle breeds and hunts near water, and fish form around half of its diet. Opportunistic, it consumes carrion and a wide variety of animals. Although rated of
Least Concern globally, it has declined in parts of southeast Asia such as Thailand, and southeastern Australia. It is ranked as
Threatened in
VictoriaVictoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....
and
Vulnerable in
South AustraliaSouth Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...
and
TasmaniaTasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
. Human disturbance to its habitat is the main threat, both from direct human activity near nests which impacts on breeding success, and from removal of suitable trees for nesting. The White-bellied Sea Eagle is revered by
indigenous peopleIndigenous Australians are the original inhabitants of the Australian continent and nearby islands. The Aboriginal Indigenous Australians migrated from the Indian continent around 75,000 to 100,000 years ago....
in many parts of Australia, and is the subject of various folk tales throughout its range.
Taxonomy
The White-bellied Sea Eagle was first described by the German naturalist
Johann Friedrich GmelinJohann Friedrich Gmelin was a German naturalist, botanist, entomologist, herpetologist and malacologist.- Education :Johann Friedrich Gmelin was born as the eldest son of Philipp Friedrich Gmelin in 1748 in Tübingen...
in 1788, although
John LathamJohn Latham was an English physician, naturalist and author. He was born at Eltham in Kent, and was the eldest son of John Latham, a surgeon there, and his mother was a descendant of the Sothebys, in Yorkshire....
had made notes on the species in 1781, from a specimen obtained in February 1780 at
Princes IslandPanaitan is an island in the Sunda Strait, between Java and Sumatra. It is the largest island in the strait, and is located near the westernmost tip of Java . Like the nearby Krakatoa, it too is volcanic in origin, although there are no known historic eruptions...
off the westernmost cape of
JavaJava is an island of Indonesia. With a population of 135 million , it is the world's most populous island, and one of the most densely populated regions in the world. It is home to 60% of Indonesia's population. The Indonesian capital city, Jakarta, is in west Java...
during
Captain Cook'sCaptain James Cook, FRS, RN was a British explorer, navigator and cartographer who ultimately rose to the rank of captain in the Royal Navy...
last voyage. Its specific name is derived from the
Ancient GreekAncient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
leuko- 'white', and
gaster 'belly'. Its closest relative is the little-known Sanford's Sea Eagle of the
Solomon IslandsSolomon Islands is a sovereign state in Oceania, east of Papua New Guinea, consisting of nearly one thousand islands. It covers a land mass of . The capital, Honiara, is located on the island of Guadalcanal...
. These form a
superspeciesA superspecies is a group of at least two more or less distinctive species with approximately parapatric distributions. Not all species complexes, whether cryptices or ring species are superspecies, and vice versa, but many are...
, and as is usual in other sea eagle superspecies, one (the White-bellied Sea Eagle) has a white head, as opposed to the other species' dark head. The bill and eyes are dark, and the talons are dark yellow as in all Southern Hemisphere sea eagles. Both these species have at least some dark colouration in their tails, though this may not always be clearly visible in the White-bellied Sea Eagle. The
nucleotideNucleotides are molecules that, when joined together, make up the structural units of RNA and DNA. In addition, nucleotides participate in cellular signaling , and are incorporated into important cofactors of enzymatic reactions...
sequences of the
cytochrome bCytochrome b/b6 is the main subunit of transmembrane cytochrome bc1 and b6f complexes. In addition, it commonly refers to a region of mtDNA used for population genetics and phylogenetics.- Function :...
geneA gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
of the two sea eagles were among those analysed in a 1996 study. Although they differ greatly in appearance and
ecologyEcology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
, their
genetic divergenceGenetic divergence is the process in which two or more populations of an ancestral species accumulate independent genetic changes through time, often after the populations have become reproductively isolated for some period of time...
of 0.3% indicates that the ancestors of the two forms might have diverged as recently as 150,000 years ago. 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.
MitochondrialMitochondrial DNA is the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert the chemical energy from food into a form that cells can use, adenosine triphosphate...
sequence of the cytochrome b locus differs very slightly from that of Sanford's Sea Eagle suggesting a relatively recent divergence after
New GuineaNew Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...
-based White-bellied Sea Eagles colonised the Solomon Islands.
The White-bellied Sea Eagle's affinities beyond the Sanford's Sea Eagle are a little less clear; molecular data indicate that it is one of four species of tropical sea eagle (along with the
African Fish EagleThe African Fish Eagle or – to distinguish it from the true fish eagles , the African Sea Eagle – is a large species of eagle that is found throughout sub-Saharan Africa wherever large bodies of open water occur that have an abundant food supply. As a result of its large range, it is known in many...
and the
Madagascar Fish EagleThe Madagascar Fish Eagle or Madagascar Sea-eagle is a large bird of prey in the family Accipitridae which also includes many other diurnal raptors such as kites, buzzards and harriers. The range of this eagle is within the Madagascar dry deciduous forests...
), while
allozymeVariant forms of an enzyme that are coded by different alleles at the same locus are called allozymes. These are opposed to isozymes, which are enzymes that perform the same function, but which are coded by genes located at different loci....
data indicate it might have a closer relationship with the sea eagles of the northern hemisphere. A further molecular study published in 2005 showed the White-bellied and Sanford's Sea Eagles to be
basalIn phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
to the four fish eagles (the two mentioned above plus the two hitherto untested species of the genus
IchthyophagaIchthyophaga is a genus of two species of eagles, closely related to the sea-eagles in the genus Haliaeetus. Both are native to southeastern Asia, from the Indian subcontinent southeast to Sulawesi. They are smaller than the Haliaeetus eagles, though overlapping in size with the smaller species of...
).
As well as White-bellied Sea Eagle and White-breasted Sea Eagle, other recorded names include White-bellied Fish-hawk, White-eagle, and Grey-backed Sea Eagle.
Description
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
wingA wing is an appendage with a surface that produces lift for flight or propulsion through the atmosphere, or through another gaseous or liquid fluid...
s 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
iridesThe iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupils and thus the amount of light reaching the retina. "Eye color" is the color of the iris, which can be green, blue, or brown. In some cases it can be hazel , grey, violet, or even pink...
are dark brown. The
cereThe Cère is a long river in south-western France, left tributary of the Dordogne River. Its source is in the south-western Massif Central, near the mountain Plomb du Cantal...
is also lead grey. The legs and feet are yellow or grey, with long black talons (claws). Unlike those of eagles of the genus
AquilaAquila is the genus of true eagles. It is often united with the buteos, sea eagles and other more heavyset Accipitridae, but more recently it appears as if they are less distinct from the more slender accipitrine hawks than believed...
, the legs are not feathered. The sexes are similar. Males are 70–80 cm (28–32 in) long 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
wingspanThe wingspan of an airplane or a bird, is the distance from one wingtip to the other wingtip. For example, the Boeing 777 has a wingspan of about ; and a Wandering Albatross caught in 1965 had a wingspan of , the official record for a living bird.The term wingspan, more technically extent, is...
ranges from 1.78 to 2.2 m (5.8 to 7.2 ft). A 2004 study on 37 birds from Australia and Papua New Guinea (3 °S to 50 °S) found that birds could be sexed reliably on size, and that birds from latitudes further south were larger than those from the north. There is no seasonal variation in
plumagePlumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...
. The moulting pattern of the White-bellied Sea Eagle is poorly known. It appears to take longer than a year to complete, and can be interrupted and later resumed from the point of interruption.
The wings are modified when gliding so that they rise from the body at an angle, but are closer to horizontal further along the wingspan. In silhouette, the comparatively long neck, head and beak stick out from the front almost as far as the tail does behind. For active flight, the White-bellied Sea Eagle alternates strong deep wing-beats with short periods of gliding.
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. The species breeds from around six years of age onwards. The lifespan is thought to be around 30 years.
The loud goose-like honking call is a familiar sound, particularly during the
breeding seasonThe breeding season is the most suitable season, usually with favourable conditions and abundant food and water, for breeding among some wild animals and birds . Species with a breeding season have naturally evolved to have sexual intercourse during a certain time of year in order to achieve the...
; 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. Australian naturalist
David FleayDavid Howells Fleay was an Australian naturalist who pioneered the captive breeding of endangered species, and was the first person to breed the platypus in captivity....
observed that the call is among the loudest and furthest-carrying of all Australian bird calls, in stark contrast to the relatively quiet calls of the
Wedge-tailed EagleThe Wedge-tailed Eagle , sometimes known as the Eaglehawk in its native range, is the largest bird of prey in Australia, but it is also found in southern New Guinea. It has long, fairly broad wings, fully feathered legs, and an unmistakable wedge-shaped tail...
.
Adult White-bellied Sea Eagles are unmistakable and unlikely to be confused with any other bird. Immature birds can be confused with Wedge-tailed Eagles. However, the plumage of the latter is darker, the tail longer, and the legs feathered. They might also be confused with the
Black-breasted BuzzardThe Black-breasted Buzzard , or Black-breasted Kite, is a large bird of prey in the family Accipitridae and the monotypic genus Hamirostra...
(
Hamirostra melanosternon), but this species is much smaller, has white patches on the wings, and has a more undulating flight. In India, the
Egyptian VultureThe Egyptian Vulture is a small Old World vulture, found widely distributed from southwestern Europe and northern Africa to southern Asia. It is the only living member of the genus Neophron. It has sometimes also been known as the White Scavenger Vulture or Pharaoh's Chicken...
has white plumage, but is smaller and has a whiter back and wings. The white tail of the White-bellied Sea Eagle in flight distinguishes it from other species of large eagles. In the Philippines, it can be confused with the
Philippine EagleThe Philippine Eagle , also known as the Monkey-eating Eagle, is an eagle of the family Accipitridae that is endemic to forests in the Philippines. It has brown and white-coloured plumage, and a shaggy crest, and generally measures in length and weighs...
, which can be distinguished by its crest; immature White-bellied Sea Eagles resemble immature
Grey-headed Fish EagleThe Grey-headed Fish Eagle is a bird of prey. Like all eagles, it is in the family Accipitridae.Grey-headed Fish Eagle breeds in southern Asia from India and Sri Lanka to Southeast asia...
s, but can be identified by their more wholly dark brown underparts and flight feathers, and wedge-shaped tail.
Distribution and habitat
The White-bellied Sea Eagle is found from regularly from
MumbaiMumbai , formerly known as Bombay in English, is the capital of the Indian state of Maharashtra. It is the most populous city in India, and the fourth most populous city in the world, with a total metropolitan area population of approximately 20.5 million...
(sometimes north to
Gujarat, and in the past in the
LakshadweepLakshadweep , formerly known as the Laccadive, Minicoy, and Amindivi Islands, is a group of islands in the Laccadive Sea, 200 to 440 km off the coast of the South West Indian state of Kerala...
Islands) eastwards in India, Bangladesh, and Sri Lanka in southern Asia, through all of coastal
Southeast AsiaSoutheast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
including Burma, Thailand, Malaysia, Indonesia,
IndochinaThe Indochinese peninsula, is a region in Southeast Asia. It lies roughly southwest of China, and east of India. The name has its origins in the French, Indochine, as a combination of the names of "China" and "India", and was adopted when French colonizers in Vietnam began expanding their territory...
, the main and offshore islands of the Philippines, and southern China including
Hong KongHong Kong is one of two Special Administrative Regions of the People's Republic of China , the other being Macau. A city-state situated on China's south coast and enclosed by the Pearl River Delta and South China Sea, it is renowned for its expansive skyline and deep natural harbour...
,
HainanHainan is the smallest province of the People's Republic of China . Although the province comprises some two hundred islands scattered among three archipelagos off the southern coast, of its land mass is Hainan Island , from which the province takes its name...
and
FuzhouFuzhou is the capital and one of the largest cities in Fujian Province, People's Republic of China. Along with the many counties of Ningde, those of Fuzhou are considered to constitute the Mindong linguistic and cultural area....
, eastwards through
New GuineaNew Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...
and the
Bismarck ArchipelagoThe Bismarck Archipelago is a group of islands off the northeastern coast of New Guinea in the western Pacific Ocean and is part of the Islands Region of Papua New Guinea.-History:...
, and Australia. In the northern Solomons it is restricted to
Nissan IslandNissan Island is the largest of the Green Islands of Papua New Guinea. It is located at , about 200 km east of Rabaul on New Britain and about 200 km northwest of Bougainville....
, and replaced elsewhere by Sanford's Sea Eagle. In
VictoriaVictoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....
, where it is otherwise scarce, it is locally more common at
Corner InletCorner Inlet is a 600 km2 bay, 200 km south-east of Melbourne, in South Gippsland, Victoria, Australia. Of Victoria’s large bays it is both the easternmost and the warmest...
and
Gippsland LakesThe Gippsland Lakes are a network of lakes, marshes and lagoons in east Gippsland, Victoria, Australia covering an area of about 600 km2. The largest of the lakes are Lake Wellington , Lake King and Lake Victoria. They are fed by the Avon, Thomson, Latrobe, Mitchell, Nicholson and Tambo...
. Similarly in South Australia, it is most abundant along the north coast of
Kangaroo IslandKangaroo Island is Australia's third-largest island after Tasmania and Melville Island. It is southwest of Adelaide at the entrance of Gulf St Vincent. Its closest point to the mainland is off Cape Jervis, on the tip of the Fleurieu Peninsula in the state of South Australia. The island is long...
. The range extends to the islands of
Bass StraitBass Strait is a sea strait separating Tasmania from the south of the Australian mainland, specifically the state of Victoria.-Extent:The International Hydrographic Organization defines the limits of the Bass Strait as follows:...
and
TasmaniaTasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
, and it is thought able to move between the islands and the mainland. There is one unconfirmed record from
Lord Howe IslandLord Howe Island is an irregularly crescent-shaped volcanic remnant in the Tasman Sea between Australia and New Zealand, directly east of mainland Port Macquarie, and about from Norfolk Island. The island is about 11 km long and between 2.8 km and 0.6 km wide with an area of...
and several from New Zealand.
They are a common sight in coastal areas, but may also be seen well inland. The White-bellied Sea Eagle is generally sedentary and
territorialIn ethology the term territory refers to any sociographical area that an animal of a particular species consistently defends against conspecifics...
, although it may travel long distances. They have been reported travelling upriver to hunt for flying foxes (
PteropusBats of the genus Pteropus, belonging to the megabat or Megachiroptera sub-order, are the largest bats in the world. They are commonly known as the fruit bats or flying foxes among other colloquial names...
). Populations in inland Australia move around as inland bodies of water appear and then dry up. In one instance, a pair came to breed at Lake Albacutya in northwestern Victoria after the lake had been empty for 30 years. The species is easily disturbed by humans, especially when nesting, and may desert nesting sites as a result. It is found in greater numbers in areas with little or no human impact or interference.
Behaviour
The White-bellied Sea Eagle is territorial; some birds form permanent pairs that inhabit territories throughout the year, while others are nomadic. The species is monogamous, with pairs remaining together until one bird dies, after which the surviving bird quickly seeks a new mate. This can lead to some nest sites being continuously occupied for many years (one site in
Mallacoota
was occupied for over fifty years). Immature birds are generally dispersive, with many moving over 50 km (30 mi) away from the area they were raised. One juvenile raised in
Cowell, South AustraliaCowell is a coastal town on Franklin Harbour on the eastern side of the Eyre Peninsula, in South Australia on the Lincoln Highway 111 km south from the major town of Whyalla...
was reported 3000 km (1800 mi) away at Fraser Island in Queensland. A study of the species in
Jervis BayJervis Bay is a large bay bounded by the state of New South Wales, the Jervis Bay Territory, and a detached enclave of the Australian Capital Territory. HMAS Creswell is located between Jervis Bay Village and Greenpatch in the Jervis Bay Territory.-History:...
showed increases in the numbers of immature and subadult birds in autumn, although it was unclear whether these were locally-fledged or (as was considered more likely) an influx of young birds born and raised elsewhere in Australia. Birds are often seen perched high in a tree, or soaring over waterways and adjacent land. They are most commonly encountered 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. Much of the White-bellied Sea Eagle's behaviour, particularly breeding, remains poorly known.
Feeding
The White-bellied Sea Eagle is an opportunistic carnivore and consumes a wide variety of animal prey, including
carrionCarrion refers to the carcass of a dead animal. Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters include vultures, hawks, eagles, hyenas, Virginia Opossum, Tasmanian Devils, coyotes, Komodo dragons, and burying beetles...
. It often catches a fish by flying low over the water and grasping it in its talons. It prepares for the strike by holding its feet far forward (almost under its chin) and then strikes backwards while simultaneously beating its wings to lift upwards. Generally only one foot is used to seize prey. 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. While hunting over water on sunny days, it often flies directly into the sun or at right angles to it, seemingly to avoid casting shadows over the water and hence alerting potential prey.
The White-bellied Sea Eagle hunts mainly aquatic animals, such as fish, turtles and sea snakes, but it takes birds, such as
Little PenguinThe Little Penguin is the smallest species of penguin. The penguin, which usually grows to an average of in height and in length , is found on the coastlines of southern Australia and New Zealand, with possible records from Chile.Apart from Little Penguins, they have several common names...
s,
Eurasian CootThe Eurasian Coot, Fulica atra, also known as Coot, is a member of the rail and crake bird family, the Rallidae. The Australian subspecies is known as the Australian Coot.-Distribution:...
s and
shearwaterShearwaters are medium-sized long-winged seabirds. There are more than 30 species of shearwaters, a few larger ones in the genus Calonectris and many smaller species in the genus Puffinus...
s, and mammals as well. In the
Bismarck ArchipelagoThe Bismarck Archipelago is a group of islands off the northeastern coast of New Guinea in the western Pacific Ocean and is part of the Islands Region of Papua New Guinea.-History:...
it has been reported feeding on two possum species, the
Northern Common CuscusThe Northern Common Cuscus , also known as the Grey Cuscus, is a species of marsupial in the Phalangeridae family. It is native to northern New Guinea and adjacent smaller islands, but is now also found in the Bismarck Archipelago, south-east and central Moluccas, the Solomons and Timor, where it...
and
Common Spotted CuscusThe Common Spotted Cuscus is a cuscus, a marsupial that lives in the Cape York region of Australia, New Guinea, and nearby smaller islands.- Description :...
. It is a skilled hunter, and will attack prey up to the size of a
swanSwans, genus Cygnus, are birds of the family Anatidae, which also includes geese and ducks. Swans are grouped with the closely related geese in the subfamily Anserinae where they form the tribe Cygnini. Sometimes, they are considered a distinct subfamily, Cygninae...
. They also feed on carrion such as dead sheep, birds and fish found along the waterline, as well as raiding fishing nets and following cane harvesters.
They harass smaller raptors such as
Swamp HarrierThe Swamp Harrier also known as the Marsh Harrier, Australasian Harrier, Kāhu, Swamp-hawk or New Zealand Hawk is a large, slim bird of prey in the family Accipitridae.-Description:...
s,
Whistling KiteThe Whistling Kite is a medium-sized diurnal raptor found throughout Australia , New Caledonia and much of New Guinea . Also called the Whistling Eagle or Whistling Hawk, it is named for its loud whistling call, which it often gives in flight...
s,
Brahminy KiteThe Brahminy Kite , also known as the Red-backed Sea-eagle, is a medium-sized bird of prey in the family Accipitridae, which also includes many other diurnal raptors such as eagles, buzzards and harriers. They are found in the Indian subcontinent, Southeast Asia and Australia...
s and
OspreyThe Osprey , sometimes known as the sea hawk or fish eagle, is a diurnal, fish-eating bird of prey. It is a large raptor, reaching more than in length and across the wings...
s, forcing them to drop any food that they are carrying. Other birds victimised include
SilverThe Silver Gull also known simply as "seagull" in Australia, is the most common gull seen in Australia. It has been found throughout the continent, but particularly coastal areas. The South African Hartlaub's Gull and the New Zealand Red-billed Gull The Silver Gull (Chroicocephalus...
and
Pacific GullThe Pacific Gull is a very large gull, native to the coasts of Australia. It is moderately common between Carnarvon in the west, and Sydney in the east, although it has become scarce in some parts of the south-east, as a result of competition from the Kelp Gull, which has "self-introduced" since...
s,
cormorantThe bird family Phalacrocoracidae is represented by some 40 species of cormorants and shags. Several different classifications of the family have been proposed recently, and the number of genera is disputed.- Names :...
s and Australasian Gannets. There is one record of a White-bellied Sea Eagle seizing a gannet when unsuccessful in obtaining its prey. They may even steal food from their own species, including their mates. 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. Southern Fur Seals have also been targeted for their fish.
White-bellied Sea Eagles feed alone, in pairs, or in family groups. A pair may cooperate to hunt. Prey can be eaten while the bird is flying or when it lands on a raised platform such as its nest. The White-bellied Sea Eagle skins the victim as it eats it. It is exceptionally efficient at digesting its food, and disgorges only tiny pellets of fragmented bone, fur and feathers.
A 2006 study of inland bodies of water around Canberra where Wedge-tailed Eagles and White-bellied Sea Eagles share territories showed little overlap in the range of prey taken. Wedge-tailed Eagles took rabbits, various macropods, terrestrial birds such as cockatoos and parrots, and various passerines including
magpieThe Australian Magpie is a medium-sized black and white passerine bird native to Australia and southern New Guinea. A member of the Artamidae, it is closely related to the butcherbirds...
s and
starlingThe Common Starling , also known as the European Starling or just Starling, is a passerine bird in the family Sturnidae.This species of starling is native to most of temperate Europe and western Asia...
s. White-bellied Sea Eagles caught fish, water-dwelling reptiles such as the eastern long-necked turtle and
Australian water dragonThe Australian Water Dragon , which includes the Eastern Water Dragon and the Gippsland Water Dragon The Australian Water Dragon (Physignathus lesueurii), which includes the Eastern Water Dragon (P. l. lesueurii) and the Gippsland Water Dragon The Australian Water Dragon (Physignathus lesueurii),...
, and waterbirds such as ducks,
grebeA grebe is a member of the Podicipediformes order, a widely distributed order of freshwater diving birds, some of which visit the sea when migrating and in winter...
s and
cootThe Eurasian Coot, Fulica atra, also known as Coot, is a member of the rail and crake bird family, the Rallidae. The Australian subspecies is known as the Australian Coot.-Distribution:...
s. Both species preyed on the Maned Duck. Rabbits constituted only a small fraction of the White-bellied Sea Eagle's diet. Despite nesting near each other, the two species seldom interacted, as the Wedge-tailed Eagles hunted away from water and the White-bellied Sea Eagles foraged along the lake shores. However, conflict with Wedge-tailed Eagles over nesting sites in remnant trees has been recorded in Tasmania.
Breeding
The breeding season varies according to location—it has been recorded in the dry season in the
Trans-Fly regionThe Trans Fly savanna and grasslands are a lowland ecoregion on the south coast of the island of New Guinea in both the Indonesian and Papua New Guinean sides of the island...
and
Central ProvinceCentral Province is a province in Papua New Guinea located on the southern coast of the country. It has a population of 183,983 people and is in size. The seat of government of Central Province, which is located within the National Capital District outside the province, is the Port Moresby suburb...
of Papua New Guinea, and from June to August in Australia. A pair of White-bellied Sea Eagles performs skilful displays of flying before copulation: diving, gliding and chasing each other while calling loudly. They may mirror each other, flying 2–3 m (7–10 ft) apart and copying each other swooping and swerving. A talon-grappling display has been recorded where the pair will fly high before one flips upside down and tries to grapple the other's talons with its own. If successful, the two then plunge cartwheeling before separating as they approach the ground. This behaviour has also been recorded as an aggressive display against a Wedge-tailed Eagle.
The White-bellied Sea Eagle usually chooses tall trees or man-made pylons to nest in. One pair were recorded using a cable tower in
Tin WanTin Wan is a place at the south of Hong Kong Island, Hong Kong. It is at the west of Aberdeen and the east of Kellett Bay .A public housing estate in there, Tin Wan Estate , is also named from Tin Wan....
in Hong Kong. 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, which is generally a low-lying locale near water with some forest cover. The perch becomes covered in faeces and pellets and animal remains litter the immediate surrounding area. The
nestA bird nest is the spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the American Robin or Eurasian Blackbird, or the elaborately woven hanging nest of the...
is a large deep bowl constructed of sticks and branches, and lined with such materials as grass or seaweed. Yearly renovations result in nests getting gradually bigger. Nests are generally sited in the forks of large trees overlooking bodies of water. Old nests of Wedge-tailed Eagles or
Whistling KiteThe Whistling Kite is a medium-sized diurnal raptor found throughout Australia , New Caledonia and much of New Guinea . Also called the Whistling Eagle or Whistling Hawk, it is named for its loud whistling call, which it often gives in flight...
s have been renovated and used. Cliffs are also suitable nesting sites, and on islands nests are sometimes built directly on the ground. A breeding pair, with the male being more active, spends three to six weeks building or renovating the nest before laying eggs. Normally a
clutchA clutch of eggs refers to all the eggs produced by birds or reptiles, often at a single time, particularly those laid in a nest.In birds, destruction of a clutch by predators, , results in double-clutching...
of two dull, white, oval eggs are laid. Measuring 73 x 55 mm, they are
incubatedIncubation refers to the process by which certain oviparous animals hatch their eggs, and to the development of the embryo within the egg. The most vital factor of incubation is the constant temperature required for its development over a specific period. Especially in domestic fowl, the act of...
over six weeks before hatching. The young are semi-
altricialAltricial, meaning "requiring nourishment", refers to a pattern of growth and development in organisms which are incapable of moving around on their own soon after hatching or being born...
, and covered in white down when they emerge from the egg. Initially, the male brings food and the female feeds the chicks, but both parents feed the chicks as they grow larger. Although two eggs are laid, it is unusual for two young to be reared successfully to
fledgingFledge is the stage in a young bird's life when the feathers and wing muscles are sufficiently developed for flight. It also describes the act of a chick's parents raising it to a fully grown state...
(leaving the nest). One egg may be infertile, or the second chick may die in the nest. If the first clutch is lost, the parents may attempt a second brood. Nestlings have been recorded fledging when 70 to 80 days old, and remaining around the parents' territory for up to six months or until the following breeding season.
Conservation status
The White-bellied Sea Eagle is listed as being of
Least Concern by the IUCN. There are an estimated 10 to 100 thousand individuals, although there seems to be a decline in numbers. They have become rare in Thailand and some other parts of southeast Asia. They are relatively abundant in Hong Kong, where the population increased from 39 to 57 birds between 2002 and 2009. A field study on Kangaroo Island in South Australia showed that nesting pairs in areas of high human disturbance (as defined by clearing of landscape and high human activity) had lower breeding success rates. In the
Eyre PeninsulaEyre Peninsula is a triangular peninsula in South Australia. It is bounded on the east by Spencer Gulf, the west by the Great Australian Bight, and the north by the Gawler Ranges. It is named after explorer Edward John Eyre who explored some of it in 1839-1841. The coastline was first explored by...
in South Australia, nests have been vacated as human activities have encroached on the eagles' territories. Elsewhere, the clearing of trees suitable for nesting has seen it largely disappear locally, such as the removal of stands of
Casuarina equisetifoliaCasuarina equisetifolia is a she-oak species of the genus Casuarina. The native range extends from Burma and Vietnam throughout Malesia east to French Polynesia, New Caledonia, and Vanuatu, and south to Australia...
in
Visakhapatnam districtVisakhapatnam district , also known as Visakha Zilla, is an administrative division of Andhra Pradesh, India. The administrative headquarters of the Visakhapatnam District is Visakhapatnam.-Post-Independence:...
in
Andhra PradeshAndhra Pradesh , is one of the 28 states of India, situated on the southeastern coast of India. It is India's fourth largest state by area and fifth largest by population. Its capital and largest city by population is Hyderabad.The total GDP of Andhra Pradesh is $100 billion and is ranked third...
in India. In India, nest densities of about one per 4.32 km have been noted in
SindhudurgSindhudurg is an administrative district in the state of Maharashtra in India, which was carved out of the erstwhile Ratnagiri District. The district headquarters are located at Oros . The district occupies an area of 5207 km² and has a population of 868,825 of which 9.47% were urban...
and one per 3.57 km (45 nests along 161 km) in
Ratnagiri districtRatnagiri district is one of the 35 districts of Maharashtra state in western India. Ratnagiri is the district headquarters of the district. The district is 11.33% urban. The district is bounded by the Arabian Sea to the west, Sindhudurg district to the south, Raigad district to the north and...
of
MaharashtraMaharashtra is a state located in India. It is the second most populous after Uttar Pradesh and third largest state by area in India...
. They also nest on Netrani Island where they are disturbed by torpedo-firing exercises conducted by the Indian navy. Nearly 100 nests have been noted on this island.
DDTDDT is one of the most well-known synthetic insecticides. It is a chemical with a long, unique, and controversial history....
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. A review of DDT's impact on Australian raptors between 1947 and 1993 found that the average egg-shell thickness had decreased by 6%. This average level of thinning was not thought likely to result in significantly more breakage overall, however individual clutches that had been even thinner might have broken. 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. DDT use peaked in 1973, but was no longer approved after 1987 and its use had effectively ceased by 1989.
Australia
The White-bellied Sea Eagle is listed under the
marine and
migratory categories which give it protected status under Australia's federal
Environment Protection and Biodiversity Conservation Act 1999The Environment Protection and Biodiversity Conservation Act 1999 is an Act of the Parliament of Australia that provides a framework for protection of the Australian environment, including its biodiversity and its natural and culturally significant places...
. As a mainly coastal species, it is vulnerable to habitat destruction in Australia's increasingly populated and urbanised coastal areas, particularly in the south and east of the country, where it appears to have declined in numbers. 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 carpThe Common carp is a widespread freshwater fish of eutrophic waters in lakes and large rivers in Europe and Asia. The wild populations are considered vulnerable to extinction, but the species has also been domesticated and introduced into environments worldwide, and is often considered an invasive...
(
Cyprinus carpio). However, it is rare along the
Murray RiverThe Murray River is Australia's longest river. At in length, the Murray rises in the Australian Alps, draining the western side of Australia's highest mountains and, for most of its length, meanders across Australia's inland plains, forming the border between New South Wales and Victoria as it...
where it was once common. It is also listed as
Threatened under
Victoria'sVictoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....
Flora and Fauna Guarantee Act (1988), with possibly fewer than 100 breeding pairs remaining in the state. On the 2007 advisory list of threatened vertebrate fauna in Victoria, the White-bellied Sea-eagle is listed as
vulnerableOn 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
.
There are fewer than 1000 adult birds in Tasmania, where the species is listed as
Vulnerable under Schedule 3.1 of the Tasmanian
Threatened Species Protection Act 1995The Threatened Species Protection Act 1995, is an act of the Parliament of Tasmania that provides the statute relating to conservation of flora and fauna. Its long title is An Act to provide for the protection and management of threatened native flora and fauna and to enable and promote the...
. In Tasmania it is threatened by nest disturbance, loss of suitable nesting habitat, shooting, poisoning, trapping, and collision with power lines and wind turbines, as well as entanglement and environmental pollution. Estuaries are a favoured habitat, and these are often subject to environmental disturbance. 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.
Cultural significance
The White-bellied Sea Eagle was important to different tribes of indigenous people across Australia. The guardian animal of the
Wreck BayWreck Bay Village is a town in the Jervis Bay Territory Australia. It forms part of the Jervis Bay Village Council. It is a largely Aboriginal community.-Geography:* coordinates: * elevation: ~30 m, 106 ft...
aboriginal community, it is also the official emblem of the
Booderee National Park and Botanic GardensBooderee National Park and Botanic Gardens are located in the Jervis Bay Territory of Australia. The reserve is composed of two sections:* the Bherwerre Peninsula, on the southern foreshore of Jervis Bay, Bowen Island and the waters of the south of the bay...
in the
Jervis Bay TerritoryThe Jervis Bay Territory is a territory of the Commonwealth of Australia. It was surrendered by the state of New South Wales to the Commonwealth Government in 1915 so that the Federal capital at Canberra would have "access to the sea"....
. The community considered localities around Booderee National Park to be connected with it. A local Sydney name was
gulbi, and the bird was the
totemA totem is a stipulated ancestor of a group of people, such as a family, clan, group, lineage, or tribe.Totems support larger groups than the individual person. In kinship and descent, if the apical ancestor of a clan is nonhuman, it is called a totem...
of Colebee, the late 18th century indigenous leader of the
CadigalThe Cadigal, also spelled as Gadigal, are a group of Aboriginal Australians who originally inhabited the area that they called 'Cadi', part of which later became known as the Marrickville Local Government Area of Sydney. Cadigal territory lies south of Port Jackson and stretches from South Head to...
people. The White-bellied Sea Eagle is important to the Mak Mak people of the floodplains to the southwest of
DarwinDarwin is the capital city of the Northern Territory, Australia. Situated on the Timor Sea, Darwin has a population of 127,500, making it by far the largest and most populated city in the sparsely populated Northern Territory, but the least populous of all Australia's capital cities...
in the Northern Territory, who recognised its connection with "good country". It is their totem and integrally connected to their land. The term
Mak Mak is their name for both the species and themselves. The
Umbrawarra Gorge Nature ParkUmbrawarra Gorge Nature Park is a nature park located 245 km south of Darwin and 115 km west of Katherine in the Northern Territory.-External links:**...
was a
DreamingThe Dreaming is a common term within the animist creation narrative of indigenous Australians for a personal, or group, creation and for what may be understood as the "timeless time" of formative creation and perpetual creating....
site of the bird, in this area known as
Kuna-ngarrk-ngarrk. It was similarly symbolic to the Tasmanian indigenous people—
Nairanaa was one name used there.
Known as
Manulab to the people of
Nissan IslandNissan Island is the largest of the Green Islands of Papua New Guinea. It is located at , about 200 km east of Rabaul on New Britain and about 200 km northwest of Bougainville....
, the White-bellied Sea Eagle is considered special and killing it is forbidden. Its calls at night are said to foretell danger, and seeing a group of calling eagles flying overhead is a sign that someone has died. Local Malay folk tales tell of the White-bellied Sea Eagle screaming to warn the shellfish of the turning of tides, and a local name
burung hamba siput translates as "slave of the shellfish". Called
Kaulo in the recently extinct
Aka-Bo languageThe Bo language, Aka-Bo , is an extinct Great Andamanese language, of the Northern group. It was spoken on the west central coast of North Andaman and on North Reef Island of the Andaman Islands in India...
, the White-bellied Sea Eagle was held to be the ancestor of all birds in one
Andaman IslandsThe Andaman Islands are a group of Indian Ocean archipelagic islands in the Bay of Bengal between India to the west, and Burma , to the north and east...
folk tale. On the Maharashtra coast, their name is
kakan and its call is said to indicate the presence of fish in the sea. They sometimes nest on coconut trees. Owners of the trees destroy the nest to avoid attacks when harvesting the coconuts.
The White-bellied Sea Eagle is featured on the $
10,000 SingaporeThe Bird Series of currency notes is the second set of notes to be issued for circulation in Singapore. Issued in the years 1976 to 1984, it has nine denominations, the same number as in the Orchid Series, albeit the $25 note was replaced by the $20 note....
note, which was introduced into circulation on 1 February 1980. It is the emblem of the Malaysian state of
SelangorSelangor also known by its Arabic honorific, Darul Ehsan, or "Abode of Sincerity") is one of the 13 states of Malaysia. It is on the west coast of Peninsular Malaysia and is bordered by Perak to the north, Pahang to the east, Negeri Sembilan to the south and the Strait of Malacca to the west...
. Malay magnate
Loke Wan ThoLoke Wan Tho born in Kuala Lumpur , was a cinema magnate, ornithologist, and photographer. He was the founder of Cathay Organisation in Singapore and Malaysia, and Motion Picture and General Investments Limited in Hong Kong....
had a 40 m (130 ft) high tower built for the sole purpose of observing a White-bellied Sea Eagle nest in the palace gardens of
Istana Bukit SereneIstana Bukit Serene is the royal palace and official residence of the Sultan of Johor, located in Johor Bahru, Malaysia. The palace faces the Straits of Johor and has a bird's eye view of Singapore, a former possession of the Sultanate....
in
Johor BahruJohor Bahru is the capital city of Johor in southern Malaysia. Johor Bahru is the southernmost city of the Eurasian mainland...
. Taken in February 1949, the resulting photographs appeared in
The Illustrated London News in 1954. The bird is the emblem of the
Manly-Warringah Sea EaglesThe Manly-Warringah Sea Eagles are an Australian professional rugby league club based on the Northern Beaches of Sydney. They compete in the National Rugby League's Telstra Premiership, the premier rugby league competition of Australasia...
rugby league team, chosen at the club's inception in 1947. 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. After raising one brood, however, their nest collapsed in February 2011. The story attracted statewide attention. A new nest was constructed nearby, two eggs laid, and one chick raised to fledging in late 2011.