Although originally classified under CORACIFORMES, hornbills are now separated and placed in the ancient order BUCEROTIFORMES together with hoopoes and woodhoopes.
Current taxonomy listings recognise 61 species in total of which two are ground-hornbills in family Bucorvidae, and the remaining 59 species, that are classed as 'typical hornbills', in family Bucerotidae.
The ground-hornbills are the largest members of the group. Both species come from sub-Saharan Africa - the Abyssinian Ground-Hornbill [Bucorvus abyssinicus] from the north, and the Southern Ground-Hornbill [Bucorvus leadbeateri] not surprisingly from the south. As their name suggests, they are mainly terrestrial birds, although still very capable of flight.
Featured species listed in taxonomic order :
The 'typical hornbills' are quite different and, although unrelated, could be regarded as the ‘Old World’ equivalent of the superficially similar ‘New World’ toucans. Across southern Asia there are 32 species, from India and the Malay peninsula east to the Philippines and Solomon Islands. They are a varied group and, as such, are placed in no less than ten separate genera. Given that our main travel interests are primarily centred around Africa and the Neotropics I doubt that I’ll ever see any of these Asian Hornbills.
The remaining 27 species are found across tropical and sub-tropical Africa. Traditionally there were 23 species until the number of taxon increased when the Red-billed Hornbill [Tokus erythrorhynchus] complex was officially split following the discovery of a new form in Southern Tanzania. Research showed that, apart from their geographical range, all the subspecies, being the northern nominate [ssp.erythrorhynchus], western [ssp.kempi], two southern races [ssp.rufirostris] and Damara [ssp.damarensis], together with the new form [ssp.ruahae], were separable by their facial plumage, skin colour around the eye and colour of the iris and, as such, should be accepted as full species. Additionally Tockus was split to form a clade for the ‘whistlers’ [Lophoceros] and the ‘cluckers’ [Tockus] - a scientific separation based on more than just the vocal distinctions between the two groups.
There are now five genera for all the African Hornbills: Tockus, Lophoceros, Bycanistes, Ceratogymna and Horizocerus.
I’ve always found hornbills fascinating and somewhat exotic birds, which is why I wanted to write a bit about them, even though I’ve only seen and photographed ten species to date. I’m pleased that this total now includes both varieties of ground-hornbill following my brief encounter with the northern form in The Gambia. My main disappointment is that my one and only sighting of the Trumpeter Hornbill [Bycanistes bucinator] back in 2012 in Selous resulted in just a poor long-distant photo that can’t be used. This is rather annoying as this particular bird is one of the more unusual species. Similarly with the Abyssinian Ground-Hornbill and the African Pied Hornbill where again I’ve only had a single sighting although, in respect of the former, I have included a photo as I wanted to be able to feature both ground-hornbill species. Hopefully in time I’ll be able to expand the set to include new species and/or replace certain photos.
Abyssinian Ground-Hornbill [Bucorvus abyssinicus]
Also known as the Northern Ground-Hornbill, this sub-Saharan species is found north of the equator from southern Mauritania, Senegal, The Gambia and Guinea in the west, across the Sahel to Ethiopia, western Somalia, Uganda and northwestern Kenya.
Abyssinian Ground-Hornbill [Bucorvus abyssinicus] | Niamina West, The Gambia
Southern Ground-Hornbill [Bucorvus leadbeateri]
The above long-distant shot is of a female bird, easily distinguishable by its all blue fascial skin, whereas the larger male has an inflatable patch of red skin on its neck and throat.
The Southern Ground-Hornbill lives south of the equator from northern Namibia and Angola in the west, across northeastern Botswana and northern South Africa including Swaziland, and north through southern Zimbabwe, Mozambique, Malawi, Zambia and Tanzania up to Burundi and southern Kenya.
The species favours woodland or savanna habitat with short grass for foraging and suitable large trees for roosting and nesting. They live in small family groups where there will be a dominant alpha pair who will be the only birds that breed whilst the other members of the group act as helpers.
Southern Ground-Hornbill [Bucorvus leadbeateri] | Katavi NP, Tanzania
The males are larger than the females, weighing up to 6kgs, but despite their size they are very capable fliers. They eat all manner of insects, snails, frogs, rodents, reptiles and even small mammals.
Southern Ground-Hornbills are classified as a threatened species, listed as 'vulnerable' on the IUCN Red List, but regarded as 'endangered' in South Africa due to rapidly declining numbers as a result of persecution and loss of suitable nesting habitat - a situation that is not helped by the species being long-lived, but slow-breeding.
Tanzanian Red-billed Hornbill [Tockus ruahae]
The Tanzanian Red-billed Hornbill is the new taxon that I referred to in the introduction and is effectively the species that was responsible for the reclassification of all the various forms. This particular species is restricted to central and southern Tanzania with Ruaha National Park being at the centre of its range, such that when the bird was first recognised as a new form it was called the Ruaha Hornbill, hence its scientific name Tockus ruahae.
Tanzanian Red-billed Hornbill [Tockus ruahae] | Ruaha NP, Tanzania
Western Red-billed Hornbill [Tockus kempi]
Whilst the Tanzanian bird has a yellow eye the same as the Southern form, it is surrounded by black rather than pale skin.
A hornbill's dominant feature is, of course, its impressive, long, down-curved bill that incorporates a ridge on the upper mandible called a casque - in some species, such as the Trumpeter Hornbill, the casque is very pronounced and serves an additional purpose in amplifying its calls, whereas with other species, notably the Red-billed Hornbills, it is barely visible with no real purpose other than strengthening the bill. To help support their large bills, all hornbills have powerful neck muscles and fused first and second neck vertebrae.
Red-billed Hornbills spend much of the day foraging on the ground whereas most of the other species are tree dwellers.
The western form of the Red-billed Hornbill is found in south Mauritania, Senegal, The Gambia and western Mali.
Western Red-billed Hornbill [Tockus kempi] | Kotu Rice Fields, The Gambia
This variant has similar black facial skin around its eye as the Tanzanian, but has a brown rather than yellow eye. All the other forms of Red-billed Hornbill - Northern, Southern and Damara - have pale facial skin.
Southern Red-billed Hornbill [Tockus rufirostris]
The Southern Red-billed Hornbill can be found from south Angola and northeastern Namibia in the west, east through Zambia and Botswana, northern South Africa, Zimbabwe and Malawi.
Southern Red-billed Hornbill [Tockus rufirostris] | South Luangwa, Zambia
Von der Decken's Hornbill [Tockus deckeni]
This form is distinguishable from other Red-billed Hornbills by the combination of yellow iris and pale, pink to greyish, orbital skin. Unfortunately I haven't photographed the remaining forms but, for the record, both the Northern [Tokus erythrorhynchus] bird and the southern Damara [Tokus damarensis] species have a brown eye and pink facial skin.
Named after the German explorer Baron Karl Klaus von der Decken, this species of hornbill is found in East Africa, mainly east of the East African Rift from Ethiopia and Somalia south to central Tanzania. It is similar in appearance to the Red-billed Hornbills except for the colour of its mandibles and the lack of spotting on its wing coverts.
Von der Decken's Hornbill [Tockus deckeni] male | Ruaha NP, Tanzania
The species has clear sexual dimorphism in that the sexes can be easily identified by the colour of their bill. The bird in the above photo is a male - it has a predominantly red bill with a varying amount of cream towards the tip. The female's bill is black as can be seen in the following photo.
Von der Decken's Hornbill [Tockus deckeni] female | Ruaha NP, Tanzania
The Von der Decken's Hornbill favours areas of dry thorn scrub or similar arid habitats.
Crowned Hornbill [Lophoceros alboterminatus]
The Crowned Hornbill can be found in the coastal and riverine forests of East Africa. It spends much of its time foraging in trees. Like most hornbills, the species is omnivorous and will take advantage of almost anything it can find to eat.
Crowned Hornbill [Lophoceros alboterminatus] | Masai Mara, Kenya
I've spent a fair bit of time watching hornbills whilst in Africa and the one thing that has always struck me is the way they use their large bills. As previously mentioned, the Red-billed Hornbills are often found on the ground where they look for small insects, which they manage to pick up and then deftly toss and catch before eating. The above photo of a Crowned Hornbill shows how delicately it can pick the smallest fruit. They can do this because they possess a special type of binocular vision that enables them to see the tips of their mandibles.
African Grey Hornbill [Lophoceros nasutus]
The African Grey Hornbill is a widespread species that can be found across much of sub-Saharan Africa. There are two recognised subspecies - the nominate [ssp.nasutus] found from Senegal and The Gambia in the west across to Ethiopia and central Kenya, and another race [ssp.epirhinus] found in East Africa from southern Kenya, south to South Africa.
African Grey Hornbill [Lophoceros nasutus] | Bansang Quarry, The Gambia
I've photographed both subspecies. The above image, taken in The Gambia, is the nominate race - a female bird identifiable by the purplish-red colouring towards the tip of its bill. The following picture is of a male bird, ssp.epirhinus. Now the interesting thing is that if you look closely you'll see that the bird in the first photo has a short casque, whereas the subspecies photographed in Zambia has a much longer and far more pronounced casque that ends in a slim raised tube.
African Grey Hornbill [Lophoceros nasutus] | South Luangwa, Zambia
Although not evident from these two photos, the southern subspecies is also a bit smaller than the nominate bird.