Haliaeetus leucogaster

Written by on November 19, 2010 in Indonesia Bird with 0 Comments

Haliaeetus leucogaster, White-bellied Fish Eagle, Elang laut perut putih

The WhiHaliaeetus-leucogaster, White-bellied Fish Eaglete-bellied Fish Eagle has a wingspan of 50cm and body length of 70cm.

White-bellied Fish Eagles are more commonly seen on warm early mornings riding the coastal thermals, holding their wings in a V-shape (other raptors hold them horizontally).

White-bellied Fish Eagles hunt prey that are found near the water surface mainly sea snakes, and fish. But other prey include birds, turtles, swimming crabs and even bats. They may also scavenge on refuse; a few haunt harbours for this purpose.

A White-bellied Sea Eagle was once observed dropping large crabs onto rocks 30-40 m below, but this is not common behaviour. If they are not feeding young, they eat their catch on the wing. They usually forage in pairs.

Like other raptors, they have excellent eyesight. To forage, they circle on a thermal to gain height, then glide over water usually low and within 1 km from the shore.

They catch their prey by skimming the water surface then snagging the prey in their talons with a backward slash. They don’t plunge into the water like Osprey do.

White-bellied Fish Eagles don’t appear to be highly territorial towards others of their kind. But they make loud harsh cries near important spots like a perch or nest. These can be heard up to 1 km away, perhaps helping to space out the birds and avoid confrontations.
White-bellied Fish Eagles are found mainly on the coast, wooded rocky shores and mangroves. Sometimes also near inland reservoirs or rivers.

Breeding: White-bellied Fish Eagles appear to pair for life. Pairs may perform aerial displays which include locking talons and tumbling together through the air to the accompaniment of loud goose-like honking.

In choosing a nest site, White-bellied Fish Eagles go for height, choosing the tallest objects near coasts or other large bodies of water (e.g., reservoirs).

These include tall emergent trees in mangroves, and man-made pylons; when a taller pylon is built nearby, they often shift to the taller one! They may also nest on islands, sometimes on a small tree growing on a cliff face. The nest can be huge (1.5 m across and 2 m tall) and is made of sticks, lined with green vegetation. The same nest is reused every breeding season and built up until it becomes a giant pile of sticks. If the original pair do not return, another pair soon takes over the old nest.

2 bluish white eggs are laid. The female incubates while the male feeds her and defends the nest from other birds and intruders.

Migration? White-bellied Fish Eagles are sedentary and don’t migrate. But immatures and unpaired adults may wander over a large area. Mated pairs tend to stay near their nesting site.

Status and threats: Although White-bellied Fish Eagles appear quite tolerant of humans and are conspicuous, they are not present in large numbers in their range, and their numbers appear to be declining. They are threatened by habitat loss which removes suitable nesting sites and prey.

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