BITTERNS MAKE A COMEBACK
WHILE the ibis nesting colony at Reedy Lake on the lower reaches of the Barwon River was devastated by the floods that came through late last month, the rare Australasian bitterns that live there seem to have survived the inundation.
Various reports suggest that as many as 1000 straw-necked ibis, as well as some white ibis and spoonbills, had established a nesting colony among the reed beds in the centre of the lake before the flood came through.
The floodwater inundated the site resulting in the loss of any eggs or nestlings that were there. The waterbird species that nest on reeds or lignum in flood-prone areas are vulnerable to this sort of impact, and they quickly recover once the floodwater recedes.
At a far greater risk from the inundation were the Australasian bitterns that are known to frequent Reedy Lake and may also have been nesting there at the same time. However, recording devices set up to "listen" for the bitterns have recorded their calls since the floodwater receded.
Though large birds – they are slightly larger than white-faced herons – they are largely nocturnal, spending much of the day hiding among the dense reed beds.
If displaced by the flood, they would need to find a similar place to spend the days. Bitterns are notoriously cryptic and quickly adopt a pose with the beak point upwards so that this, combined with the brown plumage, makes them remarkably difficult to see when they
are among reeds. But at nightfall, they become active, hunting frogs, fish and similar food in the shallow water.
It is then that they may be heard, their booming call said to have given rise to the bunyip myths. By using sound recorders at night, their presence can be detected without the need for difficult daylight searches.