| Black-and-white-casqued Hornbill | |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Bucerotiformes |
| Family: | Bucerotidae |
| Genus: | Bycanistes |
| Species: | Bycanistes subcylindricus |
The Black-and-white-casqued Hornbill or Grey-cheeked Hornbill (Bycanistes subcylindricus) is a large bird in the family Bucerotidae.
Taxonomy[]
The Grey-cheeked Hornbill is part of the genus Bycanistes, a genus of sub-Saharan hornbills that currently includes a total of six known species that all share black and white plumage and are mostly frugivores. According to recent genetic data, this genus is a sister taxon to the genus Bucorvus, also known as "ground hornbills". Most of the species of this genus have a casque on the beak, much larger in the males than in the females. The closest relative of the Black-and-white-casqued Hornbill is the Brown-cheeked Hornbill (Bycanistes cylindricus) which inhabits similar habitats.
The species is divided into two subspecies:
- B. s. subcylindricus, found in the strip of territory that goes from Sierra Leone, north-eastern Liberia and Ivory Coast to the Niger delta (western Nigeria).
- B. s. subquadratus, found in Nigeria (east of the Niger River), Cameroon, Central African Republic, Southern South Sudan, Northern and Eastern Democratic Republic of Congo, Uganda, southwestern Kenya and northwestern Tanzania; a disjoint population is also present in north-eastern Angola.
Description[]
The Black-and-white-casqued Hornbill is a large bird with black and white plumage, approximately 70 centimeters (28 inches) long. The weight varies from 1078 to 1525 g in males, and between 1000 and 1250 g in females. Like most hornbills, it has a gray-blackish beak, large for its size, with a big casque on top. Females are slightly smaller than males and have a significantly smaller casque.
In the subspecies subcylindricus, the casque is lower and completely dark brown. grooved on the sides. The rump, the outer tail feathers, the belly, the trailing edge of the wings and even the tip of the large coverts form a large white zone. The color of these light parts contrasts with the black one with green metallic reflections of the head, cape, coverts, neck and chest. The pair of central tail feathers is entirely black. A large black band covers the base of the external tail feathers. The cap feathers are bristly and form a noticeable crest. Those of the cheeks have an ash gray tip, which gives this area a very characteristic scaly appearance. The bare skin around the eyes is flesh-colored. The female is smaller, with a blackish beak and casque. The juveniles have a smaller beak and no casque.
In the subspecies subquadratus, the casque is higher, at the level of the feathers of the crest, and forms a slight curve that covers two thirds of the beak. It is black in color, except for a large ivory spot that covers almost the entire top. The beak, dark gray, has a very thin light yellow band at the base. The rest of the plumage is identical to that of the nominal subspecies. Both subspecies have very mobile eyes, a very rare trait in birds. This means that their eyes can move in their own orbit, while other birds tend to have to keep moving their heads to look around. The crest of feathers on the head are movable and are used to show emotions, which allows the bird to communicate its emotional state.
Behaviour[]
These hornbills are sedentary, but this does not prevent them from making local trips in search of fruit. Most of the time they are spotted in pairs. Very rarely, they congregate in small flocks when feeding and when roosting. These birds almost always look for food in the canopy, pecking at the fruit. They will also capture small animal prey of all kinds that they pluck from the foliage, chase in flight or find on the ground. Sometimes several individuals hunt together. They often associate with monkeys or squirrels.
Feeding[]
The Black-and-white-casqued Hornbill's diet consists primarily of fruits from at least 41 plant species. The species feeds mainly on figs, but also on small animals, such as insects, a large number of millipedes, snails, lizards, bats, nestlings plundered from other nests and small galagons. The vegetable part of the diet constitutes almost 80% of the total; the remaining 20% is made up of animal prey. These hornbills do not consume water directly and instead seem to hydrate themselves from the water contained in the fruits that make up the majority of their diet.
Breeding[]
There is probably no actual nesting season. In Central Africa the species reproduces from January to May, while in East Africa the reproduction takes place mainly from August to March. The Black-and-white-casqued Hornbill is monogamous and lives in pairs. The nest consists of a natural cavity in the trunk of a large tree at a height ranging from 9 to 30 meters. Sometimes it is found in the crevasse of a rock face. The two parents work together to close the entrance, mainly with mud balls brought by the male. The brood includes two eggs, the incubation of which lasts 42 days. The chicks are born naked, with pink skin rapidly turning dark gray. The male feeds the brood regurgitating up to 200 fruits per visit. The female does not always moult the flight feathers during the brooding period. Usually only one of the two chicks survives, as the other dies due to food shortages. The surviving chick leaves the nest between 70 and 79 days after hatching.
Distribution and habitat[]
These birds do not actually frequent a specific habitat, but rather are found in areas between evergreen tree forests and regenerating secondary woodlands. They are also present in wooded areas consisting of large deciduous trees or plantations, up to an altitude that can reach 2600 meters. The species is native to western, central and eastern Africa. Its range is divided into two main regions which roughly correspond to the distribution of the two subspecies. Its range includes mainly the Ivory Coast, with smaller populations in the surrounding countries for the populations of West Africa. Central African populations are mainly located in Uganda and Kenya, as well as in Cameroon with smaller populations in Gabon, Tanzania and Central Africa.
Conservation[]
Although it is uncommon or rare in most of West Africa and northern Angola, the species is not actually endangered. It is still quite common in central and eastern Africa, particularly along the Congo River. Its predilection for ecotones or transition zones between two habitats mitigates the consequences of deforestation, but leads to the fragmentation of the range and the establishment of isolated populations.