Colours of Wildlife: Southern Ground Hornbill
Created | Updated Jun 3, 2012
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!"
Southern Ground Hornbill
This is a painting of a Southern Ground Hornbill, Bucorvus leadbeateri. This big bird is a relative of the Sulawesi Wrinkled Hornbill and the Southern Yellowbilled Hornbill, but much larger than both. It is fairly rare overall, but easy to see in the Kruger National Park, where I've seen and photographed a few. This picture is based on several photographs; it's difficult to get a good, clear picture because these birds are mostly seen in long grass, concealing much of their bodies. I have managed to photograph them clearly on roads, but that's not a very aesthetic background!
Ground hornbills are very large birds, sometimes exceeding 6 kg/13 lbs and standing about a metre/yard tall on tiptoe. With their glossy black bodies and bright red, bare facial skin, coupled with a bold and fearless demeanor, they are conspicuous wherever they occur. But many people who see them don't know what they are, to the extent that in the Kruger National Park they now have an accepted secondary name, 'Turkey Buzzards'. This comes from American tourists, who might be thinking as much of turkeys as of actual 'turkey buzzards' which is what many Americans call the Turkey Vulture, Cathartes aurea, a species that does not occur in Africa. Most tourists are quite ignorant of African wildlife apart from obvious things like lions, rhinos, elephants and so forth. I hope that, at least for the readers of this series, I am doing something to remedy that situation!
Although related to other hornbills, Ground Hornbills are distinct enough to be placed in their own family, the Bucorvidae, alongside all the other hornbills that are in the Bucerotidae. The two families together are placed either in the order Coraciiformes along with Rollers, Kingfishers, hoopoes and bee–eaters, or placed in an order of their own, the Bucerotiformes. Apart from the Southern Ground Hornbill, there's a second species, the Northern Ground Hornbill, Bucorvus abyssinicus, that replaces it in similar habitat north of the Equator. It has a large, open casque on top of the bill, a yellow patch on the side of the bill, and blue and red (male) or entirely blue (female) facial skin. Unique features of the ground hornbills include not having carotid (neck) arteries, and walking on their toe–tips. They also have very long, dense, impressive eyelashes, used to screen their eyes from the bright African sun.
Ground hornbills, as the name indicates, spend most of their time on the ground, preferring open savannah grassland regions. They can fly up into trees, in which case they display their startlingly white primary wing feathers, that are usually hidden beneath the overlying black feathers, but most of the time they walk around with stiff–legged steps. Their legs are much longer than those of other hornbills, together with their long necks enabling them to peer over quite tall grass. They walk on their toes to boot, with the 'sole' of the foot lifted high off the ground. The result is a stately step, that gives an impression of justified pride.
They are formidable predators, going out in hunting parties of up to 11 birds. Their long, curved bills are very strong; the gap that opens from behind the bill tip to about the middle of the bill, even when it is closed, gives the tip of the bill a more favourable angle for pinching and exerting pressure. Their prey varies from termites to big tortoises and even mammals like hares. When they hunt large, fast or dangerous prey, they co–operate. To catch a snake they spread their wings out sideways and form a circle around it. The length of the bill then enables them to peck the snake to death without it being easily able to wound their heads. They also use their bills to dig around in the ground in search of invertebrates, frogs, or the honey, combs and larvae of ground–nesting bees and wasps. They also regularly probe around in dung, especially elephant dung, to look for dung beetles or their larvae. Sometimes ground hornbills eat carrion.
Unlike many other hornbill species, this one does not have a large hollow casque on top of the bill, but just a raised ridge. The function of amplifying its call is carried out by the big throat pouch instead. In the male this is entirely red; in the female it has a deep blue central patch. These colours emerge only on maturity; in chicks and juveniles, the bare facial skin is grayish. The inflatable throat pouch enables the birds to give a particularly deep, booming 'hoom hoom hoom hoom' call, from which they get their Afrikaans name 'Bromvoël' (roughly translated as 'Boom Bird'). This call sounds thinner and tinnier from close than from afar – it carries up to five kilometers/three miles, although it is not very loud. It is the deepness of the sound that gives it its carrying power. From a distance the call sounds rather like the roar of a lion. To mistake a hornbill for a lion is not as big a mistake is the opposite – as a bird lover realised to his shock when, under the impression that he was approaching a hornbill, he stumbled upon a lioness!
Although they inhabit open land, these hornbills do need trees. They roost up in the branches at night, and also nest in trees. Unlike other hornbill species, they do not imprison their females while incubating eggs. Instead the nest is a large, open cavity or hollow, often at the top of a Baobab Tree. Thus these birds need ample open ground in addition to very large trees, a particular habitat requirement that makes them vulnerable to human disturbance like the felling of trees for wood or for clearing agricultural lands. But they will adapt and can live in open farm fields provided there are big trees nearby.
Ground hornbills roost as well as hunt in pairs or small groups. To maintain group bonds they call, preen each other and exchange food items. They start hunting at dawn, and can cover 11 km/about 7 miles per day. They sometimes make use of bush fires, catching small animals as they flee from the flames. They will also catch small creatures disturbed by large animals like elephants, buffaloes or rhinos, and can often be found close to them.
Other interesting behaviours include sunbathing with spread wings, or bathing by rubbing themselves against wet leaves and grass after rains. Sometimes they accidentally step in thorns, which they pull out with the precision grasp of the bill tip. Immature birds will play with each other at the roosts, doing a kind of jousting with the bill–tips, chasing each other or jumping on each other. The birds typically fly to and from their roosts while it is still dark, so as to try and keep their roosting places secret from potential predators.
Other than baobabs, ground hornbills will also nest in large specimens of trees like Marula, Boer–Bean, Thorn (the larger species), Yellowwood, Jackal–Berry, Sausage, Fig, Bushwillow or Star–Chestnut Trees. They rarely use cavities in rock faces or earth banks. Although the female is not sealed in, she broods her eggs alone. But she has help! Her husband, as well as other members of the group, regularly bring food to her while she incubates. This is the largest bird species in the world that breeds co–operatively. Sometimes the female leaves her nest briefly for the sake of personal hygiene, leg–stretching, and to find some food for herself.
Although ground hornbill mothers always lay two eggs, it also always happens in nature that only one chick survives. The chick stays in the nest for about three months, after which it joins the group. It stays in the group until is is adult, at about the age of 4 to 6 years. We still don't know how long they live, but everything indicates that it is potentially quite long. They proliferate slowly – aside from the fact that they take long to mature, and that there's usually only one breeding female per group, and that she only raises one chick per breeding attempt, groups don't even necessarily breed every year. Chicks are also threatened by a number of predators, including cat– and snake species. On average it takes every group a bit over nine years to successfully raise
a single chick to maturity.
Many Africans living traditionally respect this bird. Some hunters use the head and neck of a ground hornbill, as well as a big black cloak or animal skin to cover their bodies, to disguise themselves as ground hornbills so as to be able to sneak up close to game! But with more modern lifestyles and habitat destruction the future for these hornbills is uncertain. Many of them die from eating poisoned bait farmers put out for jackals, caracals or other predators. In areas with buildings they are sometimes directly persecuted by humans because they attack house windows – they see their own reflections and peck the panes to pieces under the impression that it is another, strange bird. This behaviour can be prevented by painting the windows, or by putting wire netting in front of them. A final problem under which also the ground hornbills suffer is the warfare in Africa. Because they peck deeply into the ground with their sturdy bills,
they are at risk of being blown up by buried land mines. These still exist in large numbers in countries like Angola and Mozambique, remnants of wars that are technically over but still killing people and wildlife.
At least there are a few projects in motion for boosting the numbers of the ground hornbills. As I said, they usually lay two eggs, but only raise a single chick. By removing one of the eggs from the nest and raising the chick by hand, while the mother raises the other chick, conservationists can help assure that more chicks reach adulthood. For that the hand–raised chicks need to be raised as naturally as possible so that they will not have adaptation problems when they are released into the bushveld to fend for themselves. This project, mainly in South Africa, is still in its beginning phase and it is not clear how successful it will be, but it does offer a ray of hope.
