The Black- and- White -casqued hornbill

The Black- and- White -casqued hornbill

The Black-and-White-casqued hornbill : also known as the Grey-cheeked hornbill (Bycanistes subcylindricus) are fairly large and mainly black hornbills with white lower backs and rumps, upper and under tail-covers, thighs, bellies and vents. The central pair of the flight feathers on the tail is all black (rectrices), while the rest of the tail feathers are basically black and extensively white distally. The secondaries and inner primaries are mostly white with bases being black. The bird has a Grey-tipped facial feathering, which derives its other common name “Grey-cheeked Hornbills”. Movements and dispersion of these hornbills vary seasonally and this specie is also diurnal and usually travel in pairs or small groups.

Physical description

It is recognized by its black plumage for the higher body and wings alongside and white plumage on the lower body and wings with black feathers amongst the white feathers of the tail, specifically the top tail feathers. It has a broad creamy-brownish bill and flattened casque, which are enlarged in males. Males have red eyes, blackish facial skin and a dark brown bill with a high ridged, laterally flattened casque.   Females have pink facial skin and brown eyes and have much smaller all-blackish bills, the casque is decreased to a lower rounded ridge on the basal upper mandible. In males, the purpose of the casque is not clearly known although it is suggested to be for sexual characterization. The specie has mobile eyes something not common in birds meaning that their eyes move themselves in their socket whilst other birds have to move their heads to see around. The bird is also capable of displaying emotions through the feathers at the top of the head, which allows it to communicate out its emotional state. Juveniles emerging from the nest have small bills lacking casques. Birds less than a year of age have brown feathers on the forehead and around the base of the bill. Sub adults have a high degree of vascularization in the area of the future casqued. The facial feathers turn from brown to grey by the age of 10 months

Feeding

The black-and-white-casqued hornbills are mainly frugivorous, with fruit comprising 90% of their diet, 56% belonging to Ficus species. They forage by hopping from one branch to another in the forests reaching out for fruits with its tip of the bill which they then swallow wholly. They are also frequently seen foraging alongside monkeys and squirrels and the bird is well known to consume over 41 plant species in general. In addition, the species also consumes other bird’s eggs, insects, bats, snails, mollusks, lizards and other small animals. Mosses, fungi and lichens are also comprised in their diet. In this species, the carnivorous component of the diet is increased during the breeding period. The bird does not consume water directly and seems to instead hydrate itself from the water contained in the fruits that represent most of its diet. During the dry season, this species does not nest, they are nomadic, sometimes travelling over 6km to visit fruiting trees.

Reproduction

Black-and-white-casqued hornbills are monogamous (having one mate at a time) and they breed seasonally from January to May in Central Africa and August to March in eastern Africa. Their breeding season coincides with local rainy seasons, so that they can take advantage of the abundance of fruit and arthropods at this time. Black-and-white-casqued hornbill individuals nest in naturally formed cavities 9 to 30m high in large forest trees. Due to the rarity of the nesting cavities, there is an increased degree of intraspecific competition for nesting sites. As a way of protecting their nests, pairs plaster and seal the cavity or nest-hole with mud pellets collected by the male so that only a slit was left. The female does most of the work and the material is brought to her by the male. When nesting, the birds keep the material in the tips of their bills and make rapid sideways vibrating movements of their bills. Inside, the female lays a clutch of 2 eggs, which are white in color with pitted shells. The eggs are incubated for 42 days while the male delivers food to the female hourly through a small slit, regurgitating numerous fruits, mammals and insects and the male can bring up to 200 fruits per visit. Normally only one offspring is reared, with the chick from the second laid egg dying of starvation. Newly hatched chicks have pink skins and open their eyes at the age of approximately 20 days. The offspring fledge at the age of nearly 70 to 79 days and can feed themselves by 40 to 72 days after fledging.  These birds make continuous and repetitive “long-calls” and “high-pitched screams” whilst perched on tree tops.

Communication

The black-and-white-casqued hornbills are absolutely vocal, with a large collection of calls one of which can be heard from a distance of 2km. They make repetitive “long-calls” and “high-pitched screams” while perched at tree tops. It is theorized that the casque on the bill of this specie acts as a vibrating chamber to make their voice sound more powerful.

Where to find them

The black-and-white casqued hornbill is found mostly in Ivory-Coast, with smaller populations in its surrounding countries for West-African populations. The Central-African populations are mostly in Uganda and Kenya as well as Cameron with smaller populations in Gabon, Tanzania and Central Africa.