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Australasian Darter

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Habitat: Wetland, Coastal

Habitat

The Darter is found in wetlands and sheltered coastal waters. It prefers smooth, open waters, for feeding, with tree trunks, branches, stumps or posts fringing the water, for resting and drying its wings. Most often seen inland, around permanent and temporary water bodies at least half a metre deep, but may be seen in calm seas near shore, fishing. The Darter is not affected by salinity or murky waters but does need waters with sparse vegetation that allow it to swim and dive easily. It builds its nests in trees standing in water and will move to deeper waters if the waters begin to dry up.

Behaviour

Because of its long and slender neck, the Australasian Darter is sometimes called the snakebird. Usually inhabiting freshwater wetlands, darters swim with their bodies submerged beneath the water’s surface, with only the curved neck protruding above the water, enhancing its serpentine qualities. Darters forage by diving to depths of about 60 centimetres, and impaling fish with its sharp, spear-like beak. Small fish are swallowed underwater, but larger ones are brought to the surface, flicked off the bill (sometimes into the air) and then swallowed head-first.

Feeding

The Darter catches fish with its sharp bill partly open while diving in water deeper than 60 cm. The fish is pierced from underneath, flicked onto the water’s surface and then swallowed head first. Smaller items are eaten underwater and large items may be carried to a convenient perch and then swallowed. Insects and other aquatic animals, including tortoises, may also be eaten, as well as some vegetable matter. In hot weather, adult birds may pour water from their bills into the gullets of their young chicks when they are still in the nest.

Breeding

The Darter is usually a solitary bird, forming pairs only while breeding. Breeding is erratic, happening whenever water levels and food supplies are suitable, but most often occurs in spring and summer. Nests are usually solitary, but Darters may nest within loose colonies with other water birds that nest in trees, such as cormorants, spoonbills and ibis. The male decorates a nest site with green leafy twigs and displays to attract a mate, with elaborate wing-waving and twig-grasping movements. The male carries most of the nest material to the nest site, generally in the fork of a tree standing in water, usually about 3.5 m above the water’s surface. Both sexes complete the nest, incubate the eggs (for 28 days) and raise the young. The clutch size is usually four. Chicks are kept warm by brooding continuously (or cooled down by shading with spread wings) for up to a week after hatching and both adults stay in the nest with the chicks overnight. In hot weather, the adults will even shake water over the chicks after a swim. Chicks can swim after about four weeks in the nest and start to fly at about 50 days.