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Haliaeetus leucogasterwhite-bellied sea eagle(Also: white-bellied sea-eagle)

By Stephen Zahm

Geographic Range

White-bellied sea eagles are found throughout southeast Asia. They range north to south from southern China to Australia and Tasmania, and west to east from India to New Guinea. Their range includes the islands of Southeast Asia, such as Singapore, Indonesia, and the Philippines. ("Breeding Ecology of White-bellied Sea Eagle (Haliaeetus leucogaster) in Hong Kong - A Review and Update", 2010; Ferguson-Lees and Christie, 2001)

Habitat

White-bellied sea eagles live primarily in terrestrial habitats near the ocean, especially coasts, islands, and estuaries, but also live in forested areas with access to smaller bodies of water, such as lakes, ponds, and rivers. Most white-bellied sea eagles live at elevations around 900 m, with the highest elevation recorded at 1,700 m. ("Breeding Ecology of White-bellied Sea Eagle (Haliaeetus leucogaster) in Hong Kong - A Review and Update", 2010; Ferguson-Lees and Christie, 2001; "Wildlife Fact Sheet: White Bellied Sea-Eagle Haliaeetus leucogaster", 2011)

  • Range elevation
    30 to 1700 m
    98.43 to 5577.43 ft
  • Average elevation
    900 m
    2952.76 ft

Physical Description

White-bellied sea eagles average 75 to 84 cm long, have a 1.78 to 2.2 meter wingspan, and weigh 2.2 to 3.0 kg, as adults. The head, neck, belly, thighs and distal tail-feathers are white, while the back, wing coverts, primary wing, and proximal tail-feathers can be dark gray to black. All white-bellied sea eagles have dark-brown to black eyes. White-bellied sea eagles have large, gray, hooked beaks, which originate from a gray cere and end with a black hook. The relatively short legs and feet of these eagles are scaled and featherless, and can be light-gray to cream in color with large black talons. White-bellied sea eagle tails are short and wedge-shaped.

White-bellied sea eagles exhibit sexual dimorphism, with females being slightly larger than males. The average male eagle is 66 to 80 cm long, has a wingspan of 1.6 to 2.1 m, and weighs 1.8 to 2.9 kg, while the average female is 80 to 90 cm long, has a 2.0 to 2.3 m wingspan, and weighs 2.5 to 3.9 kg.

Juveniles have different coloration than adults, with the head having cream-colored feathers, except for a brown streak behind the eyes. The rest of the feathers are dark-brown in color with cream at the tip, except for the white feathers at the base of the tail. Adult plumage develops at about five years of age.

White-bellied sea eagles can sometimes be confused with the brahminy kites or Egyptian vultures. However, they can easily be distinguished because these species are much smaller than white-bellied sea eagles. Wedge-tailed eagles can also be mistaken for white-bellied sea eagles, but wedge-tailed eagles have feathered legs and more dark coloration than these sea eagles. (Einoder and Richardson, 2007; Ferguson-Lees and Christie, 2001; Shephard, et al., 2004; "Wildlife Fact Sheet: White Bellied Sea-Eagle Haliaeetus leucogaster", 2011)

  • Sexual Dimorphism
  • female larger
  • Range mass
    2.2 to 3.0 kg
    4.85 to 6.61 lb
  • Range length
    75 to 84 cm
    29.53 to 33.07 in
  • Range wingspan
    1.78 to 2.2 m
    5.84 to 7.22 ft

Reproduction

Courtship for white-bellied sea eagles begins with the male and female vocalizing in a duet. This is followed by aerial displays – including circling, chasing, diving, somersaulting, and cartwheeling with the talons locked. This behavior occurs throughout the year, but increases in frequency once breeding season arrives. Once white-bellied sea eagles have found a mate, they stay with that mate for life. However, if that mate dies, another is found. (Dennis, et al., 2011; Ferguson-Lees and Christie, 2001; "Wildlife Fact Sheet: White Bellied Sea-Eagle Haliaeetus leucogaster", 2011)

White-bellied sea eagles have a clutch size of one to three eggs, with the average clutch size being two eggs. In clutches of more than one egg, the first nestling that hatches usually kills its sibling(s). The incubation period is 35 to 44 days. Eggs are incubated by both the male and female parent. White-bellied sea eagles are nestlings for the first 65 to 95 days of life, after which time they become fledglings. Juveniles will remain with their parents for another one to four months, and will become independent by the time they are three to six months old. White-bellied sea eagles take three to seven years to mature after hatching.

The breeding season varies among localities for the species. It occurs from: October to March in India, May to November in New Guinea, June to December in Australia, and December to May throughout Southeast Asia. In each of these locations, the breeding season lasts around seven months and occurs at least partially during the spring and/or summer. This is because the breeding season of white-bellied sea eagles can be negatively affected by cold temperatures that decrease the success of breeding adults, the survival rate of juvenile eagles, and the availability of prey.

White-bellied sea eagles are most vulnerable to disturbance at the beginning of the breeding season. If disturbed, thery may abandon their nest and have a lower breeding success rate for the rest of the season.

The large nest of the species ranges in size from an average 1.2 to 1.5 m wide and 0.5 to 1.8 m deep, and is composed of sticks, leaves, grass, and seaweed. Males do most of the nest-building. Nests are reused and added onto every year, so some nests can be as large as 2.5 m wide and 4.5 m deep. White-bellied sea eagle nests are found in tall trees, high on cliffs, or in low bushes. ("Breeding Ecology of White-bellied Sea Eagle (Haliaeetus leucogaster) in Hong Kong - A Review and Update", 2010; Corbett and Hertog, 2011; Debus, 2008; Dennis, et al., 2011; Ferguson-Lees and Christie, 2001; O'Donnell and Debus, 2012; Schlacher, et al., 2013; "Wildlife Fact Sheet: White Bellied Sea-Eagle Haliaeetus leucogaster", 2011)

  • Breeding interval
    White-bellied sea eagles breed once yearly.
  • Breeding season
    The breeding season varies between regions, but is typically during the spring and summer months.
  • Range eggs per season
    1 to 3
  • Range time to hatching
    35 to 44 days
  • Range fledging age
    100 to 139 days
  • Range time to independence
    3 to 6 months
  • Range age at sexual or reproductive maturity (female)
    3 to 7 years
  • Range age at sexual or reproductive maturity (male)
    3 to 7 years

White-bellied sea eagles invest significantly in their offspring. Eggs are incubated by both the male and female parent. After hatching, both parents will brood over the nestlings for the first two weeks, and then will transition to guarding the nest from nearby. By the time nestlings become fledglings, parents will no longer guard the nest. As part of brooding, the eagles spread their wings to shield the nestlings from the sun.

The parents take brooding in shifts. While one parent is attending the nest, the other parent will hunt for prey to return to the nest. The parents will feed the nestlings bill to bill, but only for the first six weeks of life. After this time, the chicks are able to feed themselves on anything the parents bring to the nest. White-bellied sea eagle parents have different feeding styles. The female parent tends to feed all nestlings at the same time, while the male parent tends to feed the older or stronger chick first before feeding the other(s). (Debus, 2008; Ferguson-Lees and Christie, 2001; "Wildlife Fact Sheet: White Bellied Sea-Eagle Haliaeetus leucogaster", 2011)

  • Parental Investment
  • precocial
  • male parental care
  • female parental care
  • pre-fertilization
    • protecting
      • male
      • female
  • pre-hatching/birth
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • protecting
      • male
      • female

Lifespan/Longevity

In the wild, if white-bellied sea eagles survive to adulthood, they have an expected lifespan of about 30 years. Beyond this, little is known about the lifespan of white-bellied sea eagles and their lifespan in captivity has not been measured. ("Wildlife Fact Sheet: White Bellied Sea-Eagle Haliaeetus leucogaster", 2011)

  • Average lifespan
    Status: wild
    30 years

Behavior

As adults, white-bellied sea eagles are sedentary and only leave their current habitat when all resources are depleted. Juvenile white-bellied sea eagles emigrate to find their own territory once they are independent. The flight of these eagles consists of slow flaps, followed by periods of gliding with the wings in a shallow V-shape. White-bellied sea eagles attack their prey by either swooping down from a perch or swooping in after circling it from above. Smaller prey items (less than half of white-bellied sea eagle mass) are consumed in-flight, whereas larger sized prey are carried back to a perch to be consumed, except in the case of carrion, which is consumed on the ground. White-bellied sea eagles hunt in pairs (usually breeding pairs), most actively between 9:00 a.m. and 3:00 p.m. (Ferguson-Lees and Christie, 2001; O'Donnell and Debus, 2012; "Wildlife Fact Sheet: White Bellied Sea-Eagle Haliaeetus leucogaster", 2011; Wiersma and Richardson, 2008)

  • Average territory size
    3 km^2

Home Range

White-bellied sea eagles defend a territory of approximately 3 square kilometers around the nest. White-bellied sea eagles live exclusively in breeding pairs, with nests about 2 to 3 km apart. However, up to seven pairs have been recorded living in the same territory. While this is unusual, it is common for white-bellied sea eagles to share hunting ranges, as most eagles have a range of 150 km^2 for hunting, so some overlap is expected. This hunting range decreases during breeding seasons. (Ferguson-Lees and Christie, 2001; O'Donnell and Debus, 2012; "Wildlife Fact Sheet: White Bellied Sea-Eagle Haliaeetus leucogaster", 2011; Wiersma and Richardson, 2008)

Communication and Perception

The primary form of communication in white-bellied sea eagles are vocalizations, which consist of loud, goose-like honks and duck-like cries. White-bellied sea eagles have also been known to make croaking sounds when alarmed. Vocalizations are a key part of attracting mates and courtship behavior. Like most birds of prey, white-bellied sea eagles have sharp senses of sight, allowing them to spot prey from large distances. (Ferguson-Lees and Christie, 2001; "Wildlife Fact Sheet: White Bellied Sea-Eagle Haliaeetus leucogaster", 2011)

Food Habits

White-bellied sea eagles are carnivorous. They primarily prey on aquatic animals, especially fish, eels, and crustaceans, but also turtles, sea-snakes, and birds, including gulls, waterfowl, and young herons. White-bellied sea eagles have also been observed preying on mammals, such as grey-headed flying-foxes and short-eared rock-wallabies. Their large talons are what allow them to grasp such large prey items. White-bellied sea eagles are opportunistic feeders and have even been known to steal food items from other birds of prey. (Corbett and Hertog, 2011; Debus, 2008; Einoder and Richardson, 2007; Ferguson-Lees and Christie, 2001; Klose, et al., 2008; O'Donnell and Debus, 2012; "Wildlife Fact Sheet: White Bellied Sea-Eagle Haliaeetus leucogaster", 2011; Telfer and Garde, 2006; Wiersma and Richardson, 2008)

  • Animal Foods
  • birds
  • mammals
  • reptiles
  • fish
  • carrion
  • aquatic crustaceans

Predation

Adult white-bellied sea eagles have no predators. However, juveniles are preyed upon by monitor lizards, snakes (such as pythons), and birds (such as crows). The only defense they have against these predators is the protection of their parents. (Corbett and Hertog, 2011)

  • Known Predators
    • monitor lizards (Varanus species)
    • snakes (Serpentes)
    • crows (Corvus species)

Ecosystem Roles

White-bellied sea eagles are apex predators, preying on many species of fish, reptiles, birds, and mammals. White-bellied sea eagles are also kleptoparasitic, meaning that they steal prey from competing raptors. One of their strongest competitors are wedge-tailed eagles, both for food and for territory. Another competitor are osprey. Because they often capture their prey in the water and carries it to land, white-bellied sea eagles are important for transferring nutrients from a marine system to a terrestrial system. (Corbett and Hertog, 2011; Dennis, et al., 2012; Ferguson-Lees and Christie, 2001; Schlacher, et al., 2013; "Wildlife Fact Sheet: White Bellied Sea-Eagle Haliaeetus leucogaster", 2011)

Economic Importance for Humans: Positive

There are no known positive effects of white-bellied sea eagles on humans.

Economic Importance for Humans: Negative

There are no known adverse effects of white-bellied sea eagles on humans.

Conservation Status

White-bellied sea eagles are designated as a species of Least Concern by the IUCN and has no special status from CITES. However, this species is protected by law in Tasmania. The global population number of white-bellied sea eagles is difficult to estimate, but believed to be between 1,000 and 10,000 individuals. The population is in decline and the species is on the verge of becoming Vulnerable. To combat this, measures are being taken to create buffer zones around white-bellied sea eagle territories to prevent them from being disturbed by humans, who are the biggest cause of the population decline. ("CITES", 2015; Dennis, et al., 2011; "Haliaeetus leucogaster", 2014a; "Wildlife Fact Sheet: White Bellied Sea-Eagle Haliaeetus leucogaster", 2011)

Other Comments

The genus name comes from the Greek hali – meaning “at sea” – and aetos – meaning “eagle”. The specific epithet comes from the Greek leuko – meaning “white” – and gaster – meaning “belly”. Other common names for white-bellied sea eagles include white-breasted sea eagles and white-bellied fish eagles. White-bellied sea eagles are not considered “true” eagles because they lack the feathered legs characteristic of the group. ("Haliaeetus leucogaster", 2014b; Ferguson-Lees and Christie, 2001; "Wildlife Fact Sheet: White Bellied Sea-Eagle Haliaeetus leucogaster", 2011)

Contributors

Stephen Zahm (author), Indiana University - Purdue University Fort Wayne, Mark Jordan (editor), Indiana University-Purdue University Fort Wayne.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

acoustic

uses sound to communicate

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

carrion

flesh of dead animals.

chemical

uses smells or other chemicals to communicate

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

estuarine

an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

male parental care

parental care is carried out by males

marsh

marshes are wetland areas often dominated by grasses and reeds.

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

piscivore

an animal that mainly eats fish

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

scavenger

an animal that mainly eats dead animals

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

visual

uses sight to communicate

young precocial

young are relatively well-developed when born

References

Hong Kong Biodiversity. Breeding Ecology of White-bellied Sea Eagle (Haliaeetus leucogaster) in Hong Kong - A Review and Update. 18. Hong Kong: Hong Kong Biodiversity. 2010. Accessed February 23, 2015 at http://www.afcd.gov.hk/tc_chi/publications/publications_con/files/IssueNo18.pdf.

2015. "CITES" (On-line). Accessed March 09, 2015 at http://cites.org/.

2014. "Haliaeetus leucogaster" (On-line). Encyclopedia of Life. Accessed February 23, 2015 at http://eol.org/pages/914514/details#CITEREFLiddellScott1980.

International Union for Conservation of Nature and Natural Resources. 2014. "Haliaeetus leucogaster" (On-line). The IUCN Red List of Threatened Species. Accessed February 23, 2015 at http://www.iucnredlist.org/details/22695097/0.

State of Tasmania. 2011. "Wildlife Fact Sheet: White Bellied Sea-Eagle Haliaeetus leucogaster" (On-line). Parks & Wildlife Service Tasmania. Accessed May 19, 2015 at http://www.parks.tas.gov.au/file.aspx?id=6914.

Corbett, L., T. Hertog. 2011. Diet and Breeding of White-bellied Sea-Eagles Haliaeetus leucogaster in Subtropical River Habitats in the Northern Territory, Australia. Corella, Vol.35(2): 41-48.

Debus, S. 2008. Biology and Diet of the White-bellied Sea Eagle Haliaeetus leucogaster Breeding in Northern Inland New South Wales. Australian Field Ornithology, Vol.25(4): 165-193.

Dennis, T., S. Detmar, A. Brooks, H. Dennis. 2011. Distribution and Status of the White-bellied Sea Eagle, Haliaeetus leucogaster, and Eastern Osprey, Pandion cristatus, Populations in South Australia. South Australian Ornithologist, Vol.37(1): 1-16.

Dennis, T., G. Fitzpatrick, R. Brittain. 2012. Phases and Duration of the White-bellied Sea Eagle Haliaeetus leucogaster Breeding Season in South Australia and the Implications for Habitat Management. Corella, Vol.36(3): 63-68.

Einoder, L., A. Richardson. 2007. Aspects of the Hindlimb Morphology of Some Australian Birds of Prey: A Comparative and Quantitative Study. The Auk, Vol.124(3): 773-788.

Ferguson-Lees, J., D. Christie. 2001. Raptors of the World. Great Britain: A & C Black Ltd.. Accessed February 23, 2015 at http://books.google.com/books?id=hlIztc05HTQC&pg=PA390#v=onepage&q&f=false.

Klose, S., J. Welbergen, A. Goldizen, E. Kalko. 2008. Spatio-temporal Vigilance Architecture of an Australian Flying-Fox Colony. Behavior Ecology and Sociobiology, Vol.63: 371-380.

O'Donnell, W., S. Debus. 2012. Nest-sites and Foraging of the White-bellied Sea Eagle Haliaeetus leucogaster on the Subtropical Eastern Coast of Australia. Australian Field Ornithology, Vol.29(3): 149-159.

Schlacher, T., S. Strydom, R. Connolly, D. Schoeman. 2013. Donor-Control of Scavenging Food Webs at the Land-Ocean Interface. PLoS One, 8/6: e68221.

Shephard, J., C. Catterall, J. Hughes. 2004. Discrimination of Sex in the White-bellied Sea-Eagle, Haliaeetus leucogaster, using Genetic and Morphometric Techniques. Emu, Vol.104(1): 83-87.

Telfer, W., M. Garde. 2006. Indigenous Knowledge of Rock Kangaroo Ecology in Western Arnhem Land, Australia. Human Ecology, Vol.34(3): 379-406.

Wiersma, J., A. Richardson. 2008. "Foraging of White-Bellied Sea Eagle Haliaeetus leucogaster in Relation to Marine Fish Farms in Tasmania" (On-line). Accessed February 23, 2015 at http://fpop.fpa.tas.gov.au/staffPublications/58791_V33_3_P71_79_Wiersma.pdf.

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