The Australasian Grebe Tachybaptus novaehollandiae is sometimes known as the Little Grebe, but that bird belongs to another, mainly northern hemisphere, species which sometimes wanders to Australia. It is definitely not a duck.
This is one of two bird species that can bewilder or infuriate an observer by diving silently and disappearing for about half a minute, silently reappearing a long way from where it was originally seen. Grebes are diving birds that collect small animal prey — in this case, water insects, shrimps and other invertebrates — by chasing them underwater. They are different from ducks (that almost never chase their prey, especially not underwater) by having feet that are not webbed. Instead they have toes with lobes on them. These lobes act a bit like webs, but allow much greater flexibility by still being separate from each other. Grebes also have their legs so far back that they have difficulty walking on land, which they seldom do except during breeding. This leg position greatly increases their ability to dive and swim underwater very quickly.
There are three species of grebes commonly found in Australia: the Great Crested Grebe, a large bird found on la
rge lakes, the Hoary-headed
Grebe, found on large water bodies of any sort and the Australasian Grebe, which is found on smaller dams and pools. As a result, this is a common bird on farms in the Goulburn area, where it will breed readily. Australasian Grebes prefer to nest on mounds of green water ribbons that are floating or even that are attached to the bottom but last long enough to act as islands during breeding.
The baby grebes leave the nest as soon as they can and are carried about on the backs of their parents when they need rest or shelter. They are fluffy and striped to start with before growing to adult size. They remain striped for a while longer, then take on non-breeding colours. As with many wetland birds, the greater the numbers of water plants, such as water ribbons and knot weed, the greater the number of insects and other small animals.
Australasian grebes are small for waterfowl, about the size of peewees or Indian mynas. In w
armer months, when they are breeding, they are dark grey/brown birds with black heads with a chestnut side stripe, bright yellow eyes and a diagonal yellow mark at the base of their short, white-tipped, dagger-like beaks. Their undercarriage is fluffy and brown, fading to a very fluffy white rear with a small to invisible tail. We often call them Fluffy-bums as they move around the wetlands alone or in the company of ducks, moorhens and coots. They have been observed following coots and snatching up water life disturbed by the larger birds.
When not breeding, in the cooler months, Australasian grebes lose their bright colours and their lower faces and necks become white, giving them an overall rather sombre grey/brown and white appearance. The territorial pairs become more sociable and may join in larger groups until the next breeding season.