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Sealed for safety – a Southern yellow-billed hornbill’s nest

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We were relaxing at our campsite at Palmwag, in the Damaraland area of Namibia, when we noticed a lone Southern yellow-billed hornbill (Tockus leucomelas) energetically flitting to-and-fro across the dry river bed that fronted our campsite.  It didn’t take long for us to realise that his attention was focussed on one particular tree on the far bank of the river and we watched his activity more carefully.  This closer attention revealed that the bird’s short forays followed a definite pattern – he would fly off in a fairly random direction, stay away for a few minutes and return to the same spot in the same tree, alighting on a branch for a moment or two before dropping down to the trunk of the tree.

Feeding through the tiny opening

During one of his excursions we nipped across the river to see the object of his attentions.  As we suspected, we found that his mate was walled up into a nest in a hollow section of the tree trunk.

Cleverly disguised nest entrance

The opening to the nest, just a narrow vertical slit through which the male could pass food to the female, was about one-and-a-half metres above the ground and although we didn’t want to interfere with the process by getting too close, we thought that we could see movement in the dark interior of the nest.

Male bringing food to nest

The male was tireless in his efforts to provide food and we wondered if there were fledglings in the nest, or if a very hungry female was still incubating the eggs.  We watched the male taking lizards or geckos to the nest, and in the early morning when there was a collection of grasshoppers enjoying the sun on the wall of the camp ablution block, he made several trips between this spot and the nest to make the most of the bonanza.  Although hornbills are largely fruit eaters, the male was clearly not averse to feeding his mate (and possibly her brood) on lizards and grasshoppers during this period.  His hunting prowess was admirable, and the trips were completed very quickly.

Collecting food is a never-ending job

Southern yellow-billed hornbills are monogamous birds, and, like the example described above, often nest in hollow trees, closing the female into the nest with a wall of mud mixed with their own faeces, for the duration of the incubation period.  The female lays a clutch of three or four eggs a few days after being walled in, and these take approximately 24 days to hatch.  The chicks are not ready to leave the nest for another 45 days or so, although the female will break out of the nest before this as the nest becomes too crowded.  During the time the femle is inside the sealed cavity, she will undergo a complete simultaneous moult, perhaps triggered by the darkness of her nest, and this is in contrast to the sequential moult of males and non-breeding females.

Southern yellow-billed hornbill

Unfortunately we didn’t stay at Palmwag long enough to find out the outcome of this breeding episode, but we were certainly impressed with the efforts that the male hornbill put into providing for his family.

Collecting food

Bird of the week – Week 15 : Southern yellow-billed hornbill

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The hornbills are a very distinctive and curious group of birds, with their enormous bills, often decorated by a casque. On the ground, they look as though they should have great difficulty in holding up their heads and when flying the large nose is quite witch-like. But, of course, the bill is a lot lighter than it looks.
Southern yellow-billed hornbill
The Southern yellow-billed hornbill is a common resident of the bushveld, arid thornveld and savanna of Southern Africa. It is classified as a near-endemic in the region, with its range extending northwards into Angola.
As hornbills go, the yellow-billed hornbill variety is medium in size, its length being about 45 cm. The massive, deep yellow bill gives the bird its rather expressive Afrikaans name of “Geelbekneushoringvoël” which can be translated at “Yellow-mouthed, horn-nosed bird”. Its eyes are yellow, surrounded by a patch of bare pink skin, and it has a white belly, grey neck, and black back decorated with numerous white spots and stripes, The sexes are alike in plumage, although the male is slightly bigger than the female and has a bigger bill.
Southern yellow-billed hornbill
The Southern yellow-billed hornbill is often a solitary bird, or may be found in pairs or small groups. It forages mostly on the ground for rodents, insects, centipedes and so forth, and also for seeds and fruit. It has a habit, delightful to watch, of picking up a piece of food in the tip of its large bill and then tossing it backwards towards its throat so that it can be swallowed.
Southern yellow-billed hornbill
The call of the Southern yellow-billed hornbill is a loud wuk, wuk, wuk, often while prominently perched at the top of a tree and it will sometimes call in chorus with another bird.
The breeding habits of the hornbill are well known, the nest being a natural hole in tree, lined with dry grass and leaves, into which the female is sealed by the male, often using his own faeces,  at breeding time. Three to five eggs are laid and they hatch after 24-26 days, but the female will remain sealed into the nest for a further three weeks or so before breaking out.
Southern yellow-billed hornbill
The scientific name for the Southern yellow-billed hornbill is Tockus leucomelas; “tockus” being onomatopoeic for the birds call and “leucomelas” from the two Greek words “leykos” meaning white or bright and “melas” meaning black. Thus a black and white bird that goes “tock”. Close enough!