Shrieking gulls wheeling high in the sky broadcast there was tension in the air. Looking about me, I noticed the flotillas of Pacific black ducks and coots were behaving strangely on the open waters of the smaller of the two reservoirs at the Waterworks Reserve.
The ducks and coots were huddled together in a tight circle, whereas usually they are spread out across the expansive waters.
I soon discovered what was causing concern on a beautiful spring day – a white-bellied sea eagle perched on an outer branch of a towering stringy-bark at the water’s edge.
The eagle proved a magnificent sight. Standing upright on its perch, the plumage on the eagle’s breast shone a dazzling white in the early-morning sunlight. To the unease of the other birds, the eagle stayed in the same spot for about 10 minutes, bending its head occasionally to preen its feathers, balancing its body on giant talons gripping the branch.
On rare occasions, I had seen sea eagles at the reserve in the past but these were always juveniles in grey-brown plumage. Presumably, these were young birds spreading their wings after leaving their parents, scouting the Waterworks reservoirs as a possible hunting spot. They have aways moved on, however.
The reservoirs appear unsuitable for sea eagles, possibly because they lack the shallows in which fish are found close to the surface. Large fish are the sea eagles’ main prey which is snatched from the water’s surface as the birds swoop down from above. Along the coastline, the eagles also feed on beached and sea-washed carrion which forms an important component of their diet.
The white-bellied sea eagle has a wide range, occurring throughout south-east Asia, and the entire coastline of Australia.
It is, however, listed as vulnerable in Tasmania and South Australia and classed as threatened in Victoria due to the extensive development of coastal areas. They breed in a large nest on rocky headlands or cliffs or in large trees near the coast and along estuaries like the Derwent, and are sensitive to human disturbance during the breeding season.
Breeding pairs hold large territories of a few kilometres in diameter, and are resident in these territories year-round, defending them from other white-bellied sea eagles.
Normally a clutch of two off-white, oval eggs are laid. Initially, the male brings food and the female feeds the chicks, but both parents feed the chicks as they grow larger. Nestlings are ready to leave the nest when about two and half months old, remaining around the parents’ territory for up to six months or until the following breeding season.
The sea eagle at the Waterworks moved position momentarily, shuffled its feathers and dropped from its perch. In languid flight it was on its way, flying east towards the Derwent. And now the gulls and ducks could breathe easy once again.