A common sighting on telephone poles next to the road, the southern pale chanting goshawk has a fascinating secret life, revealed by Gerard Malan.
In the late 1700s, the French collector and ornithologist François Le Vaillant was gathering plants and animals in the Cape when he encountered a raptor with long bright-orange legs, an orange beak, dark eyes and a slate-grey body. Because this bird had a melodious and chanting ‘kleeu-kleeu-kleeu’ call, he named it the ‘singing falcon’.
Today we know this caller as the southern pale chanting goshawk. To find this raptor in Southern Africa is not a difficult task if you are in the arid parts of the region. A common and resident bird, it has a habit of perching on telephone poles next to the road, which makes it easy to see.
During the 12 years I studied a population of southern pale chanting goshawks in the Klein Karoo, I made some interesting discoveries. It is a perchand-wait hunter, so spends long periods sitting on poles and trees looking for prey. When the bird spots a rodent running across the road, it will fly gently down to the ground. Its grey colour helps it to blend into the background and the soft wing feathers allow it to fly in near silence.
After a smooth landing, the action really starts. The southern pale chanting goshawk is blisteringly fast as it runs with those long legs to catch the prey. These birds are so fast on foot they can easily catch a sunspider! They also use their long legs with great effect to poke in woody shrubs to catch a poor mouse trying to hide.
Southern pale chanting goshawks feed predominantly on rodents and, in the Klein Karoo, the bush vlei rat, Brant’s whistling rat and the four-striped grass mouse are the preferred species. The rats are large enough to supply the bird with sufficient food to last a day. But the typical rapacious chanting goshawks will eat just about anything they can catch on the ground, up to the size of game birds and hares. Other preferred items include small birds and reptiles, as well as some invertebrates. Interesting is that they feed on one- to two-weekold leopard tortoise hatchlings. They swallow these small animals whole and can do so only when the carapace (outer shell) is still soft.
They also like to eat harvester termites and will sit at the nest entrance pecking the termites as they leave the nest. Of course, the soldiers in the termite colony are quickly alerted and the southern pale chanting goshawk is then attacked. I’ve often seen the scenario where the bird, still trying to eat termites, stands on one leg while shaking the other to get rid of the termites hanging on to it. When the afflicted hunter cannot stand the biting any more, it flies to the next termite nest entrance to continue feeding.
Sometimes they forage in family groups, catching animals flushed by group members. Once you spend time with them, you will notice that throughout their range they also follow honey badgers, as well as other small carnivores and reptiles, in an effort to catch the prey they disturb.
Nests of silks and socks
The nest of the southern pale chanting goshawk is typically built of sticks in the top third of a shrub or tree. Because of the general scarcity of tall trees in the Klein Karoo, nests are placed not higher than three or four metres from the ground. The record low, as far as I know, is a nest placed on top of a thorny ground creeper on a sand dune in the Namib Naukluft Park. One problem these birds have is that predators such as caracals and genets can easily climb their nest trees. To prevent their eggs and nestlings being eaten, they often select a nest tree that grows in a thorny shrub to hinder predators climbing the tree or a tree festooned with plant creepers to hide the nest from the ground.
Southern pale chanting goshawks belong to a group of raptors that use pale-coloured insulating material such as wool to line their stick nest. In Levaillant’s days, dead woolly animals were abundant, so nesting material for chanting goshawks was abundant too. Nowadays, sheep wool has taken this role, but in areas where sheep are not farmed, such as the Klein Karoo, the birds have a second nesting problem. Here they convert to using fabricated material such as cloth, hessian, toilet paper, nappies and materials that cannot be mentioned in a family magazine. More than once I’ve seen a recognisable piece of material, such as a sock, being moved from nest to nest.
Noteworthy is that they also use the silk nests of social spiders (Stegodyphus sp.) to line their own nests. When the chanting goshawks collect spider nests to line their own nests, the tiny spiders inside the nest are transported for relatively long distances (that is, for the spiders – Ed.). Since the tiny social spiders are unable to move between areas as ants attack and eat them, they get a free flight with the southern pale chanting goshawk and, in the process, the colony travels a few hundred metres.
In the ecological network of the goshawk, members not only interact, but are also dependent on each other. You too will be mesmerised if you make time to listen for its melodious call next time you are in the Karoo or Kalahari at sunset. Le Vaillant himself was so impressed that in 1799 he wrote it was second in beauty only to the ringing call of the African fish eagle.
What’s in a name?
The scientific name for the southern pale chanting goshawk is Melierax canorus, the Melierax meaning ‘melodious hawk’ (from Greek) and the canorus, ‘to be musical and to sing’ (from Latin). The southern part in the common name is to distinguish it from its first close relative, the eastern pale chanting goshawk from East Africa. The pale part in the name separates it from the second chanting goshawk, the dark chanting goshawk found in the woodlands of Southern Africa. The Afrikaans name is bleeksingvalk.
*Professor Gerard Malan of the Tshwane University of Technology is a raptorphile with a research interest in the southern pale chanting goshawk.
This article first appeared in Wild Spring 2010.