Hoopoes and hornbills | Bucerotiformes

Families in this order

• Hornbills | Bucerotidae15 speciesMedium-sized to very large birds with a long, downcurved bill topped in many species by a horny structure, the casque, which ranges from a low keel to a hollow crest and is kept light by internal air spaces. The head is narrow, so that the bird can see its own bill tip; the first two neck vertebrae are fused and the neck muscles and collarbones are reinforced to carry the weight of the bill, and the eyelids bear long, stiff lashes. The bill tip works as a pair of forceps: food is held between the mandibles, tossed into the air with a short jerk of the head and so delivered to the throat, the tongue being too short to work it back. In the tree-dwelling species the female walls herself into a cavity with a mixture of mud, droppings and fruit pulp until only a narrow vertical slit remains, through which the male feeds her and later the young; she stays there for weeks to months and in some genera moults flight and tail feathers all at once during that time. The ground hornbills depart from this: they do not seal the nest, forage on foot on the ground and breed in groups with helpers. The flight is heavy and in the larger species loudly whooshing, because the wing coverts do not fully close over the upper arm and the air beats through between the flight feathers.
• Hoopoes | Upupidae1 speciesA long, thin, slightly downcurved bill is driven into the soil to the hilt; the bird can force the two halves apart while they are still buried, to seize a beetle grub or a mole cricket, working at the same time with strong, short-clawed feet. The crest is a row of black-tipped feathers that can be raised into a fan and otherwise lies flat along the head. The broad rounded wings are boldly barred black and white and give an undulating, flopping flight that suggests a large butterfly more than a bird. Breeding is in an unlined cavity; the sitting female and the young give off a foul liquid from the preen gland that smells of rotting meat, and the young also squirt their droppings at an intruder.
• Wood-hoopoes and Scimitarbills | Phoeniculidae4 speciesNine species in two genera make up this exclusively African family, four of which occur in this region. Wood-hoopoes and scimitarbills are slender and long-tailed, with black plumage that shimmers violet, blue or green depending on the light. Their long, graduated tails are often marked with white. The thin bill is moderately decurved in Phoeniculus and sharply sickle-shaped in the scimitarbills (Rhinopomastus). It is a probing tool, worked into bark crevices, under loose bark and into rotten wood for insect larvae, beetles and spiders. The birds hitch and clamber along trunks and branches on strong, curved toes, and often hang upside down. Wood-hoopoes travel through woodland in noisy family parties. The group proclaims its territory with a rising chorus of cackling calls, which is often rocked back and forth on a branch as a display. Scimitarbills are quieter and usually seen alone or in pairs. Nests are in tree cavities, usually old woodpecker or barbet holes. The female incubates two to four eggs alone. In the Green Wood-hoopoe, which is well studied, helpers from earlier broods feed her and the nestlings. Groups roost together in cavities to save heat on cold nights. A pungent secretion from the preen gland, strongest in nestlings, gives the nest a rank smell that is thought to deter predators, hence the local name 'stink bird'.