Colours of Wildlife: Giant Coua
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Giant Coua
Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours. . . but actually many media including 'digital' paintings with the computer!"
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Today we look at yet another group of birds restricted to the amazing island of Madagascar. Our present representative is the Giant Coua, Coua gigas. Now first of all, what is a coua? A coua is a member of the Cuckoo Family, the Cuculidae. But like most members of that family, it is not a brood parasite. Only a bit under half of the cuckoo species, including the well-known Eurasian Cuckoo, lay their eggs in other birds' nests. The couas are not like that; they make their own nests and raise their own chicks. Couas are predominantly ground-living, although a couple of species will frequent trees. It has been hard to select a representative species of the group, but I decided on the giant coua because it is the most impressive. It is not the largest member of the cuckoo family (a few of the coucals, the channel-billed cuckoo, and the coral-billed ground cuckoo, equal or exceed it) but it is by far the largest of the surviving couas. It reaches 62 cm/24.5" in length and in shape is somewhat reminiscent of a pheasant. It has a long tail and strong, stout legs. It occurs in the drier, more open forests of the west of Madagascar.
Other couas are similar but smaller. Most have brownish, greenish or greyish plumage, and are similar in general shape. All of them have extensive bare skin around their eyes, which is usually mainly bright blue, but with additional red-pink patches in a couple of species including the giant. I remarked on my entry about the Asities that many Madagascan birds have bright blue colours on their faces and/or bills. A few species have patches of brighter colours in their plumage, and the blue coua is entirely dark blackish-blue. Three species have conspicuous crests. Couas have strong, decurved bills, that of the giant couas being the largest. They have short, rounded wings and can't fly well. About ten species survive to the present day. They likely all evolved from a coucal or malkoha-like species (malkohas being mid-sized non-parasitic cuckoos found in Asia and Africa) that made it to Madagascar a dozen or so million years ago, and subsequently diversified into many species. They differ enough from other cuckoos that they are put in either a tribe or a sub-family of their own.
One species, Delalande's Coua (also known as the Snail-eating Coua) went extinct in historic times. It was (at the time Europeans discovered Madagascar) restricted to a small island off the coast. It rapidly went extinct mainly due to the forest of its tiny island home being completely destroyed, and today its sole remains are a few specimens that were sent to museums. It was one of the largest and most attractively coloured of the couas, being mostly bluish in the body, with a white throat and breast, and a rufous belly. It used stones as anvils to beat its snail prey against to rid them of their shells. Several likely 'coua stones' still survive as tragic reminders of this vanished species.
Another coua, Coua berthae, was truly gigantic, about twice the dimensions of the present-day giant, which would have made it by far the largest of the couas as well as the largest member of the cuckoo family. Sadly this species went extinct before Europeans first visited the island, so we have no idea of its plumage and bare skin colours.
The largest survivor, the giant coua, leads a mostly terrestrial life, frequenting the leaf litter of the floor of the drier, more open forests of western Madagascar. It usually dwells alone, in pairs or small family groups. It starts its day by seeking sunny spots in the understory, ruffling its feathers so the sunlight can penetrate to its skin to warm it up rapidly. It then starts walking and looking for prey amidst the dry leaves. It eats mostly invertebrates, such as the grubs or adults of beetles and moths. It also eats a small amount of plant food such as seeds or fruits.
Like most of the cuckoo family, it is quite vocal. Either from the ground or from low in a tree, it utters a deep 'wok-wok-wok�' call. Another call is described as a guttural 'ayoo-ew'; yet another as a resonant 'kookookookoogogo', with the 'gogo' part being lower in pitch than the 'kookoo's. It also makes short grunting sounds. Cuckoos all over the world often have names that reflect the kind of 'coo' sounds of their calls: apart from cuckoos, there are coucals, koels, and couas.
Giant couas nest in trees, typically at a height of 3-10 m/10'-33'. The nest is made of twigs, leaves and bark, in the form of a bowl, and lined with leaf petioles (stems). The clutch is typically 3 eggs. Not much more seems to be known about its breeding habits.
Because giant couas have a wide distribution in Madagascar, and utilize a variety of forest, woodland and scrub types, they are not considered endangered at the present time. But, as with everything else, they are dependent on their habitat being preserved and maintained in fairly healthy condition.
