Dawn Chorus

27May
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The Cape Robin was for many years always the first to greet the dawn in our garden. Then quite recently a pair of Hadedas took up residence in a nearby coral tree, and we are now very often woken by their strident calls first thing in the morning. Last summer they successfully raised two chicks that have since joined their parents on early morning forays into the surrounding veld, so we are even more aware of their presence. Despite their noisy ways we are fond of the Hadedas, and being early risers are not inconvenienced by their cacophony.

The other morning we were woken neither by the Hadedas nor even the Robin, but by a complete orchestra of bird-calls. Behaviour of this sort usually indicates that a snake, mongoose or some similar threat has been located and we at first presumed that our local mongoose family was on the prowl. When the calls continued unabated, we decided that a snake, possibly a boomslang – tree snake - was investigating the Weavers’ nests.

It was Caryl who first spotted the reason for the uproar: a Spotted Eagle Owl, well-hidden by the surrounding foliage, was perched at the top of the tree outside our living-room windows. The upper branches of the tree were filled with an avian army of singing and chanting protestors, to which the owl paid not the slightest heed. Only occasionally did it deign to open an eye, otherwise showing every sign of settling down for a well earned rest after a busy night’s hunting. For the rest of the day the owl, other than for a brief departure on some unknown errand that was soon accomplished, remained where Caryl had first found him (or was it her?). If we walked in the vicinity it would half open a yellow eye and follow our movements, but otherwise remained almost immobile, and after some time the demonstrators dispersed to go about their own business, and the owl settled down for a good day’s sleep.

Having discovered its exact whereabouts it was now easy, despite its grey and white camouflage, to pick out its form from our bedroom window, the tufted ‘ears’ being a giveaway. The purpose of the apparent ears on various species of owl is unknown, but they appear to be linked with habitat and behaviour, and it is possible that they may facilitate communication, to warn predators or, as in our case, to alarm the gathering ‘protestors’ intent on moving the owl from their territory. The actual ears are hidden, but are remarkably acute, and it is believed that the hearing of an owl is hundreds of times better than that of most diurnal birds. Hearing is used to pinpoint the position of prey, the rustle of leaves providing the equivalent of the GPS co-ordinates of a scuttling rodent. In some species the ears are placed asymmetrically, and it is thought that this helps the owl more accurately to ‘fix’ the position of a noise.

Spotted Eagle Owls prey largely on rodents, but also on frogs, reptiles and other birds (hence the vigorous early morning protests). After a veld-fire cleared surrounding bush we once came across an area above which owls had roosted for a considerable period. The ground was covered to a depth of some centimetres with disintegrating pellets containing bones and insect parts encased in rodent fur. As owls do not, of course, have teeth they cannot chew their food and have to swallow it whole. Comparatively large pieces of bone or insect chitin that remain undigested collect in the gizzard and have to be regurgitated. Wrapped in fur and with a covering of mucous, these pellets slide easily up the gullet. The collection that we found must have been produced by generations of owls, for in the deepest layers there was no longer any trace of fur, merely a myriad of small bones.

Towards dusk we kept a constant watch on our visitor. The ‘ears’ remained visible until well after the sun had set, but after dark, when I went out with a torch, the owl had flown on silent wings.

Cape Robin – Cossypha caffra. (Afrikaans - Gewone Janfrederik. Xhosa - Ugaga.)

Hadeda – Bostrychia hagedash. (Afrikaans - Hadeda. Xhosa - Ing’ang’ane.)

Spotted Eagle Owl – Bubo africanus. (Afrikaans - Gevlekte Ooruil. Xhosa - Ifubesi.)

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