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!"

We're still on the topic of the strange and unique inhabitants of the great island of Madagascar. Today we look at a Velvet Asity, Philepitta castanea. In Malagasy, the name is pronounced 'Ah-see-tee'. Asities are another group of birds entirely restricted to Madagascar. It has long been a puzzle what their closest relatives are. This species was first named as a species of thrush. Asities have also been considered to be starlings, sunbirds or even birds of paradise! After detailed study of their anatomy and genes, scientists now consider the group to be one of a handful of old-world suboscine birds. Those are songbirds that are not quite as 'advanced' in their voice boxes as the major group of songbirds, the oscines. Most suboscines live in South and Central America. The old-world representatives are the Broadbills and the Pittas. And, as it turns out, the asities.

Today asities number only four species: the velvet asity, Schlegel's asity, common sunbird-asity and yellow-bellied sunbird-asity. The sunbird-asities have in the past been considered actual members of the sunbird family, but when their vocal cords were studied, it became clear that they were suboscines, and they are now known to be quite closely related to the other asities. Being suboscines, they are only extremely remotely related to the sunbirds and to all other oscine songbirds. The asities seem closest to the broadbills, even in some classifications being considered a subfamily of the broadbills. It is possible that asities are descended from a broadbill or broadbill ancestor that landed on the island a couple of dozen million years ago. All asities are small birds, characterized by large and bright wattles around their eyes. These wattles are green and blue, and acquire their intense colour not through pigments but through an arrangement of collagen fibres, which is a unique method of coloration in the animal kingdom. It is a strange feature of Madagascan birds that many of them, in quite unrelated families, sport bright wattles or bright blue or green colours on their facial skin or on their bills.

The velvet asity is the best known of the asities. It is in technical ornithological terms a 'birb', being very cute, and also a 'borb', being quite round. It reaches a total length of 16.5 cm/6.5". It is a rainforest bird, occurring in the east of the island, at mid-altitudes, being rare both in low-lying forest and in high mountain forest. My picture shows an adult male in the breeding season. Females have a dull, olive-green and yellow plumage, with streaks on their breasts and bellies. The male outside the breeding season has yellow tips to his black body feathers. When the breeding season arrives, the yellow tips wear off, leaving the whole body deep, velvety black – except for a yellow patch on the underside of the wing and at the alula or 'bastard wing' at the 'wrist' of the wing. This yellow is usually not visible except when the bird displays. After the breeding season, he moults and his new plumage again is yellow-tipped.

The breeding male also has large, striking wattles on his face. They run from the base of the bill above his eye to his nape on each side, and are almost a glowing bright neon green, with a patch of blue right above each eye. When he is excited, the wattles engorge with blood and enlarge, so that the two 'horns' at the front touch each other. The wattles are lost, however, outside of the breeding season: they shrink down to a thin, barely-perceptible rings around the eye. Another interesting feature of the male is that he acquires his adult plumage late in his life. In his first two years of life, he looks just like the female, even when he is already sexually mature.

A feature that explains why asities were at a time considered relatives of the birds-of-paradise, is that they are polygynous. Males display in small territories, close to each other, similar to the 'leks' where other polygynous species like the ruffs and birds-of-paradise display. The territory is chosen not for the resources it contains, but for aesthetic features such as lighting and setting to allow the male to show off his wares to the max. His display includes calls, which are thin and sounds rather like a squeaky toy. He also produces a loud whirring sound in flight, which is made by special wing feathers. He stretches forward or upward, opens his mouth to show the bright yellow interior, spreads his wings to show the yellow patches on the wrist area, and may even perform acrobatics, swinging fully around his perch like a gymnast doing a giant swing. Some of these displays are intended for rival males in the vicinity, while others are directed at females. Females visit the territories as the males display, choose the one they like best, and mate. A very showy male may thus mate with several females. The male takes no further interest in the female or the chicks. She goes off and builds a nest. Asity nests are similar to those of the broadbills. They're constructed of fine moss and other plant fibres, somewhat untidily woven together, and hanging from a twig. She pushes her bill into this mass to make an opening. Above the nest opening is a shelf-like extension or canopy, perhaps to shelter the nest chamber from rain. She lays typically three eggs, incubates them and raises the chicks herself.

The reason that velvet asities can practice polygyny is that they are frugivores living in a rich, rainforest environment that provides food throughout the year. Thus, a female asity can without too much strain gather food for herself as well as for her chicks without male assistance. Asities are unusual in that they eat fruit mostly in the forest understory rather than in the canopy. The understory is dimly lit, and the fruit that are produced there are often red or orange to make them more conspicuous. Many of the food plants of the velvet asity are in the Rubiaceae or coffee family. It is an important seed distributor for several understory shrubs. After digesting the flesh, it passes out the seeds in its droppings. Having travelled through its digestive system, the seeds have their coats weakened and are primed to germinate.

In addition to fruits, velvet asities also feed on nectar. They're not as highly adapted to this as are the sunbird-asities. They use their tongues to probe into flowers; the tongues are forked and have brush-like tips to gather in dollops of nectar. Asities also on occasion eat small insects, as they find them in or around the plants they visit for fruit or nectar, but also sometimes hunting them specifically. They sometimes occur in small groups, perhaps family members, or may join mixed-species foraging flocks. They sometimes ascend to feed in the forest canopy.

The wildlife of Madagascar is in trouble. Environmental destruction continues, as forests are cut or burnt down to make way for farms and other human developments. Being strict rainforest specialists, asities cannot survive once their forest homes are destroyed. Fortunately, they occur in many of Madagascar's nature reserves, but their survival depends on these reserves being respected and their habitat being left alone.

Willem

06.11.23 Front Page

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