The Ark Files - DIVERS, DIVERS, & DARTERS

Australia has some of the world's most remarkable waterbirds with clever ways of catching their prey. Some dive on it from above; others chase and catch it from behind. Some pluck their prey from the surface of the water while others stalk and then pounce. Some use their beaks to spear, stab or hook their prey, while others use them to dig and probe.

Shag on a Rock

Cormorants are diving birds which use their large, webbed feet, their long necks and long, sharp-hooked bills to help them with shallow water diving and underwater swimming. They can hunt for fish, crustaceans, yabbies and insects under water for up to 30 seconds at a time, diving with their eyes open, their wings clasped close to their bodies for steering and braking, and their feet beating powerfully. Sometimes they eat as much as one fifth of their own body weight.

After fishing you can see them standing with their wings stretched out to dry, as their feathers are not waterproof -- hence the expression "standing like a shag on a rock". Usually cormorants hunt on their own, but on the Amazon in Brazil they work in teams of up to 1000 birds, herding whole shoals of panic-stricken fish into the shallows where the birds then break ranks and dive for their catch.

Snake Bird

The darter is closely related to the cormorant and swims with much of its body under the water. With only its slender head and s-shaped neck showing, it looks like a snake rising from the water and is often called a snake-bird. As it dives, its wings are partly open and its large webbed feet help it to swim strongly in search of small tortoises, insects and plants.

A darter swims with its neck folded back, and when it reaches forward to catch its prey, two specially adapted neck vertebrae enable the neck to snap forward like a trigger. The bird then spears the prey on its sharp pointed bill before returning to the surface, flicking the fish off its bill and swallowing it.

Knives, Forks &...?

Wading on its long legs through the shallower waters of lagoons and marshes or along the shore is the spoonbill. Measuring about 20 centimetres long, the bill widens and flattens at the tip just like a spoon. The bird sweeps its bill backwards and forwards beneath the surface of shallow water, snapping shut within 25 milliseconds of a small fish, insect and crustacean touching the inside of the bill tip. Then, with an upward flick of its head, the food is thrown back and swallowed!

The teeth-like knobs inside the bill also help to crush food. More than 700 different items have been found in a spoonbill's stomach!

Fitting the Bill

The largest of the Australian wading birds, long-billed curlews prefer estuaries, mud flats and soft, sandy beaches where they feed either alone or in loose groups by probing for crabs, shellfish and worms with their long, down- curving beaks. The curlew's beak is four or five times the length of its head!

Built-in Toolbox

Oystercatchers are attractive birds that can be seen along quiet, deserted beaches, scratching around the rocks and on the shoreline. When the tide goes out you can see them digging for molluscs, cockles, worms and snails, thrusting their bills deep into the sand. As you approach they often run away a short distance, then fly in a circle over you and back to their original place.

The oystercatcher's long, straight, orange-red bill flattens at the end into a chisel shape which it uses first to remove shellfish from rocks and then to hammer a hole into the shells before prizing them open. The bill is also used to turn over seaweed and stones. Their beaks can actually change shape (depending on their diets) from thick and blunt to more slender and narrow. (Experts say that oyster-catchers in Australia eat few, if any, oysters!)

Baggy Bills

The most amazing thing about the pelican is its large bill which has an expanding front skin pouch capable of holding 10 litres of fish, crustaceans and water! The throat pouch varies in colour depending on whether it is courting, nesting or non-breeding time .Pelicans are at home on fresh or salt water mainly in lagoons, large lakes and billabongs. Sometimes they will group together in a squadron to feed, usually in shallow water, surrounding a school of fish and beating their wings. Then, with great precision, they all dip their heads into the water. If a fish swimming within their circle manages to escape one baggy bill, it is likely to swim straight into another.