White-bellied Sea Eagle

Let’s fly across Australian Marine Parks to learn about the White-bellied Sea Eagle

   

 White-bellied sea eagles are powerful sea predators that fly, feed and nest across the coastline of South Australia. If you look in Australian Marine Parks you might even be able to spot one of these magical birds in action! 

 The white-bellied sea eagle is a bird of prey often called 'raptors' – a group of birds that feed on other animals and have a keen eyesight to spot prey from far away.  

 You probably won’t be surprised to hear that white-bellied sea eagles have a white underside and head, while their back and wings are dark grey and black. Their wingspan is huge – stretching more than two metres wide!   


Importance of Marine Parks

Australian marine parks provide a safe place for marine species, including the white-bellied sea eagle. This is particularly important regarding the feeding grounds that white-bellied sea eagles utilise. Protecting these marine areas means that fish and other food sources sea eagles need to survive can flourish.

 It is the protection of the prey items within marine parks that make them an essential component in maintaining the safety of magical and threatened birds such as the white-bellied sea eagle.  


Classification

White-bellied sea eagles are Aves, the class in which all bird species fall.

They are from the Accipitridae family, a group of birds that mostly feed on prey, and are well-known for having hooked bills. Many well-known hawks, eagles, and kites are also part of the Accipitridae family, and they are found on all continents excluding Antarctica.

White-bellied sea eagles are in the Haliaeetus genus, alongside all other sea eagle species.

 Kingdom – Animalia   

Phylum – Chordata 

Class – Aves

Order – Accipitriformes

Family – Accipitridae

Genus and Species – Haliaeetus leucogaster

 Where can you find the White-bellied Sea Eagle? 

Australian Distribution

In Australia, white-bellied sea eagles can be found in all coastal locations off the mainland and offshore islands. They can also travel far distances inland along the larger waterways, which occurs mostly in the eastern states. Australia is lucky enough to be home to 5,000 - 6,000 breeding pairs of the white-bellied sea eagle, making up around one-third of the global population. 1 

In South Australia, the latest surveys indicate there are around 70 to 80 breeding pairs of white-bellied sea eagles, with the local population currently in decline. 2  The pairs spread far across South Australia, with populations occurring west of Ceduna, utilising the Great Australian Bight Marine Park; and as far east as inland on the River Murray.

There are multiple sets of breeding pairs off the coast of Kangaroo Island (and in both the Southern and Western Marine Park), as well as off the coast of Eyre Peninsula. 2 

 More than 80% of the white-bellied sea eagle breeding population in South Australia occurs on offshore islands (including Kangaroo Island). These islands are crucial to the species' long-term conservation in South Australia. 3   

They have known territories in the Great Australian Bight marine park, Western Eyre marine park, and the Southern and Western Kangaroo Island marine parks of the south-west network. 2 


Distribution

Where can you find the white-bellied sea eagle globally?

The white-bellied sea eagle can be found far and wide across the southern hemisphere. They can be spotted across southern Asia, including from India to Sri Lanka, southern China and throughout south-east Asia, the Philippines, Papua New Guinea, and, of course, Australia.

 White-bellied sea eagles are considered relatively common in most of these regions, with estimations of global population exceeding 15,00020,000 breeding pairs .  1   

Habitat

White-bellied sea eagles love to live near bodies of open water, including large rivers, swamps, lakes, and of course the open ocean. They can often be spotted at sites in coastal regions, such as around bays and inlets, beaches, lagoons, estuaries, and in mangrove forests. Additionally, they can be present in freshwater lakes, dams, rivers, and water reservoirs.

 They rely on water for feeding and foraging, however nest in terrestrial habitats which are nearby to these bodies of water.  

These habitats can be in grasslands, tidal flats, cliffs, woodlands, or forests. Nesting trees are commonly large eucalyptus trees, with lots of dead branches which they can use to protect themselves.

In South Australia there is a lack of large trees on the coast, therefore the small population of white-bellied sea eagles is often seen on open coastal landscapes, building nests along cliffs, or rocky outcrops. 2  This commonly occurs on remote offshore islands, within close distance of feeding grounds in the ocean.

 These areas are particularly exposed to disturbances, which can cause sea eagles to abandon their nests, causing devastating effects for this already highly threatened species.  


Sea Country

White-bellied sea eagles occur throughout First Nations’ Sea Country. Sea Country includes all oceans, beaches, land, and freshwater coastline. It covers all plants and animals, including the white-bellied sea eagle.

Sea Country encompasses the weather, sky, and People. It includes all living things, beliefs, values, spirits, and cultural obligations from coastal areas.

White-bellied sea eagles can fly and hunt throughout all Sea Country. However many of their nesting sites occur in Wirangu, Barngarla, Nauo, and Narungga Sea Countries, as well as on Karta Island.


Role in the ecosystem

What do White-bellied Sea Eagles eat?

White-bellied sea eagles generally hunt from a perch, or whilst in flight, where they pounce and swoop up the prey in their feet!

Prey is then usually carried back to their nest or land to be consumed, or if small it can be swallowed mid-flight. White-bellied sea eagles are opportunistic feeders – the definition of a non-fussy eater. They feed on a wide variety of prey, adapting to whatever is available!

They often hunt in marine waters, eating a variety of fish species, water birds, and aquatic reptiles. 1  At times they hunt on land, eating reptiles and small mammals - as well as carrion, the decaying parts of already dead animals (delicious).


Reproduction

White-bellied sea eagles are true romantics – once they choose a life partner, they are together forever!

They first begin breeding when they are around six years old, and they mate in solitary and monogamous pairs that are together for life. In southern Australia, the breeding season occurs from May to January, with eggs being laid from June to September. 5 

The white-bellied sea eagle’s nest acts as their house and breeding location to raise their young. The nests are large and are made up of sticks, leaves, grass, and seaweed. They are commonly built in tall eucalyptus trees, but can also be made in bushes, mangroves, caves, on the ground, or as is particularly common in South Australia, on rocky outcrops or cliffs. 4 

 Pairs of the white-bellied sea eagle usually return to the same breeding area each breeding season, with separation from other breeding pairs.  

The white-bellied sea eagle's eggs are a dull white colour, and each sea eagle pair usually lays two eggs each season (although this can vary from one to three eggs). For six weeks the females mostly incubate the egg, which includes keeping them warm and protecting them from predators.

After six weeks, the eggs are hatched and both parents feed their young hatchlings for around twelve weeks. After this stage, the white-bellied sea eagle young become ‘fledglings’ and are still fed for up to three months by their parents after they have learnt to fly. Around four months after fledging, the sea eagles are driven out of their nest by their parents – and left to fend for themselves.


Tourism

The threatened nature of white-bellied sea eagles in South Australia makes them a tricky species to spot when out and about and it is highly recommended that we do not disturb sea eagles, especially their nesting sites. 

However,  Big Duck Boat Tours  in Victor Harbor often sight sea eagles soaring over the water for a feed on their boat tours in Wirrina Cove. You might also spot the white-bellied sea eagle when out on a tour with  Kangaroo Island Ocean Safari  or  Kangaroo Island Marine Adventures .


Environmental Threats

The white-bellied sea eagle is listed as ‘Least Concern’ on the. Global Status IUCN Red List of Threatened Species, so globally it is suggested that their population is stable. However, locally here in South Australia, they are listed as Endangered. This means that our local populations are shrinking at a concerning rate, and we need to take action to ensure they do not become extinct in this region.

Habitat destruction and other threats

The main threat posed to white-bellied sea eagles is habitat loss, likely due to land development, as well as disturbance of nesting pairs by human activity. Clearing land reduces the amount of appropriate habitat available for sea eagles to nest in, causing birds to move to areas that are not ideal, and hence their breeding success is reduced.

If the sea eagles are approached by humans or human-related activities occur near their breeding grounds during the breeding season, there is a chance they may abandon their young, causing populations to decline. Examples of this have occurred locally in South Australia, particularly on the Eyre Peninsula and the far south-west coast where areas have been developed for tourism, and there has been an increase in human activity and vehicles.

Climate change is also an increasing threat, as longer periods of drought will become more common, and sea eagles' freshwater and estuarine habitats will shrink. Some nest sites may be at risk of damage due to increased storm intensity and sea level rise impacts. Furthermore, there have been examples of sea eagles becoming caught in ocean plastic pollution, such as fishing nets and lines.

 This factsheet is part of the University of Adelaide's Fab Five project, focused on raising awareness of five fabulous species and the marine parks that help protect them. This 'Our Marine Parks Grants' project received grant funding from the Australian Government. 


References

1. Debus, S., Australasian eagles and eagle-like birds. 2017, Calyton South, VIC: CSIRO Publishing.

2. Dennis, T.E. and S.A. Detmar, A review of White-bellied Sea Eagle distribution and population stability over time in South Australia. South Australian Ornithologist, 2018. 43(1-2): p. 55-72.

3. Dennis, T.E., S. Detmar, and A. Brooks. Distribution and status of White-bellied Sea-Eagle, Haliaeetus leucogaster, and Eastern Osprey, Pandion cristatus, populations in South Australia. South Australian Ornithologist, 2011. 37: p.1-16.

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

5. Dennis, T.E., S. Detmar, and C. Paterson, The White-bellied Sea Eagle as a key indicator species by which to measure the health and stability of coastal biodiversity in South Australia., W.a.E. Department of Land, South Australian Government Editor. 2015: South Australia.