The Silvery-cheeked Hornbill (Bycanistes brevis), sometimes put in the genus Ceratogymna, is a raven-sized, boldly black and white-patterned bird found in the tropical and subtropical forests of eastern Africa, from Ethiopia to South Africa. It is still common in some areas, but has experienced significant declines in others, mainly from deforestation. They are bold, noisy birds who can sometimes occur in fairly large flocks.
Hornbills belong to a family of birds found in warm climates of Africa and Melanesia. They all have large beaks, and many, like the Silvery-cheeked, have “casques” on top of the beak, some quite elaborate. They look heavy, but the walls of the beak and the casque are supported by an interior fretwork of supportive solid tissue, so that the beak is surprisingly lightweight. The color of the beak, casque and un-feathered facial features of this species are quite variable.
Most species of bird have an uropygial gland, also called an oil gland, which is a sebaceous (secreting) bi-lobed gland located on top of the base of the tail, usually hidden by overlaying feathers. Birds can frequently be seen reaching their beaks to the base of the tail and then preening. They do this to pick up a small amount of oily secretion the nature and properties of which vary among different species. For some birds, like ducks and grebes, it provides waterproofing, but it may also help control parasites, reduce feather wear, and may even be anti-microbial in at least some species. The duct through which the secretion reaches the beak (and in some species, the foot) to be distributed, through preening and head-rubbing among the feathers, opens at the top of a papilla. That is a nipple-like structure visible to an onlooker only at close range. My research including standing next to a hornbill as he preened. Like toucans, hornbills have amazingly fine-tuned beak-dexterity and can squeeze the oil out gently enough so as not to cause any damage, as I have tried to show in this painting.
When it is time to nest, the male will swallow lumps of soil which mix with saliva to form pellets in the gullet. They are then regurgitated out for the female to take and apply to the edges of the hole in a tree (or sometimes a hole among rocks) in which she will nest, with three to 48 pellets vomited at time, and then stuck in place to dry, like adobe. It may take months to create a proper seal across most of the nest with just a small slit for the female and young to be fed by the attentive male. Amazingly the male can hold swallowed fruit in the gullet for over half an hour without any digestion occurring. The chick (almost always only one, rarely two) and mom only break out of the sealed entrance when the youngster is ready to fly, although if necessary, the female can break out at any time.
The painting is 30 X 14 inches, in oils on compressed hardboard.
Barry Kent MacKay
Bird Artist, Illustrator
Studio: (905) 472 9731
31 Colonel Butler Drive
Markham, ON L3P 6B6 Canada