Working for birds in Africa

Photospot: Ground-rollers of Madagascar

p 116-119
Crossley's Ground-roller, Madagascar
Frank Hawkins
Long-tailed Ground-roller, Madagascar
Pete Morris
Short-legged Ground-roller, Madagascar
Pete Morris

Africa and its islands have no shortage of near-mythical birds. Some, like Congo Peacock, Afropavo congensis, seem set to remain so for a good few years yet, but for others, the clouds of mystery are lifting. This process often starts with the realisation that it is possible for visitors to go and see the near-myth, but it is usually many more years before much gets learnt about the birds' ecology. The ground-rollers of Madagascar are a case in point. They are usually terrestrial, silent, shy, skulking and elusive. However, at times they are none of these things, and to the lucky observer in the right place at the right time, they are extremely beautiful birds. The rainforest species, lurking in deep shade, do not often reveal their true colours, but a close view, with eyes accustomed to the dim light, reveals an unexpected array of turquoises, indigoes, purples and reds, and even brightly coloured bare parts. Close encounters with these birds are among the most treasured ornithological experiences.

Most taxonomists place the five species of ground-rollers in their own family, Brachypteraciidae, endemic to Madagascar, although some lumpers have made them a subfamily of the rollers Coraciidae. In fact, no taxonomic study has rigorously examined the group; even Sibley and colleagues, lacking DNA from any species, could reach no firm conclusion. All do, however, agree that there are five species in three genera. Four species (in two genera) are restricted to humid evergreen forest, with the remaining monotypic genus in the arid, spiny forest of the south-west.

All species nest as solitary pairs in holes in the ground (usually in a slope or embankment), excavated by the birds, like bee-eaters and many kingfishers, but unlike the true rollers, whose nest cavities are rarely in the ground, and never excavated by the birds themselves. They are largely terrestrial, but often ascend to a horizontal branch to sing. Their songs consist of far-carrying hoots, which may reveal them to be common in areas where observers otherwise find no trace of their presence; they seem only to call in the breeding season, and searching for them during the southern winter is often fruitless. Food items are mostly invertebrates, small reptiles and frogs.

The Pitta-like Ground-roller, Atelornis pittoides, is the most widespread species, quite commonly seen and heard during November around the main trail system at Ranomafana National Park. It is the only species to have been found on Montagne d'Ambre, an isolated rainforest in the far north, and in the north-western Sambirano region, and has even occurred off the mainland, on Nosy Mangabe in the north-east. Its congener, the Rufous-headed (or Crossley's) Ground-roller, A. crossleyi, is absent from these outlying areas, but locally common in parts of Ranomafana National Park and at Maromiza, an area close to, but slightly higher than, the famous Périnet (Analamazaotra) Special Reserve. It has been claimed that it occurs at sea level, but all documented records seem to come from above about 900 m, suggesting that it is a montane species; any lowland records need to be reported in full (and the pages of Bull. ABC are available for such records).

The larger rainforest ground-rollers comprise the genus Brachypteracias. The Short-legged Ground-roller, B. leptosomus, has been widely recorded in recent surveys of eastern rainforest areas. It is often seen perched in a tree, but prey is usually picked from the ground. At Marojejy Strict Nature Reserve in August to October 1988, 27 sightings of this species were all at altitudes below 1,000 m, despite considerable effort above this level. This suggests a preference for low to mid altitudes, although the upper limit clearly varies geographically. Perhaps the most bizarre of the rainforest species is the Scaly Ground-roller, B. squamiger. Its superbly scaled pattern, with shades of bronze, green and rufous, contrasts quite unexpectedly with bright pink legs and (unfeathered) eye patch, and sky-blue tail tip. It is highly terrestrial, running and stopping, rummaging in leaf litter or pulling up earthworms, and disappearing with ease in tangled rainforest undergrowth. This, too, seems to be a lowland species, best known from the Masoala Peninsula, but it occurs patchily as far as the extreme south-east (and in Mantady National Park, close to Périnet).

The fifth species, the Long-tailed Ground-roller, Uratelornis chimaera, is restricted to a small portion of the south-western spiny forest, north of the town of Toliara. The bird behaves fairly like the Atelornis species, but is rather easier to see in its more open habitat, raising and lowering its tail like a gigantic prinia. Its habitat is unprotected and threatened with destruction and degradation, making this species and the equally extraordinary Subdesert Mesite, Monias benschi (restricted to the same area) among the highest priorities for bird conservation in the Afrotropics. Their best-known haunt, near Ifaty, is becoming terribly degraded by wood extraction, mainly for charcoal production. The extent of such degradation, and its effect on the birds, are urgent topics for investigation.

How rare and threatened are these birds? The rainforest species are increasingly widely recorded, but mostly in undisturbed forest. They certainly occur at high density in some places, but have not been found in others. Thus, they seem to be patchily distributed within their preferred habitat zone, as are many tropical forest birds. This makes risk assessment very difficult, but more surveys are being undertaken annually and casual observations can certainly add to knowledge. Here, therefore, are five good reasons to visit Madagascar; the visitor will find many more!

Acknowledgements

This article was inspired by the superb photographs taken by Pete Morris and Paul Thompson. The text is based on Langrand's Guide to the birds of Madagascar (Yale, 1990), Collar & Stuart's Threatened birds of Africa and related islands (ICBP, 1985), two papers in Bird Conservation International vol 2, no 3 (Evans et al, Marojejy Strict Nature Reserve, pp 201-220 and Thompson & Evans, Ambatovaky Special Reserve, pp 221-237), conversations with Frank Hawkins and Nigel Collar, and personal experience.

Note: photographs of all five Ground-rollers illustrate this article in Bulletin of the African Bird Club 2.2.

Roger Safford

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