Bucerotiformes share many characteristics with Coraciiformes from which they are now separated.

Classification As originally defined, the Coraciiforme order did not respect monophyly (i.e., property of a clade comprising all descendants of a common ancestor and only these), since phylogenomic analysis showed that Piciformes were included in it. Monophyly was restored by recognizing Bucerotiformes, Piciformes and the remaining Coraciiformes as separate orders.

Upupidae (Hoopoes) are pictured in ancient egyptian and cretan toombs. They take insects and other small invertebrates by probing the ground with their long, downcurved bill. They are well known for their foul, smelly nests and for the musty odor that is produced by the female preen gland. In addition to the eurasian species, one other species (U. africana), found from Ethiopia to South Africa, has recently been recognized.

Pheniculidae (Woodhoopoes) get their food mostly from tree trunks. Like the hoopoes, they have smelly nests and the musty body odor during the breeding season.

Bucerotidae (Hornbills) have developped a unique nesting behaviour.The female enters the nest cavity before laying starts; the male brings mud and debris, which the female takes and plasters around the entrance until only a slit is left. The male passes food to the female through the slit until after the young are more or less grown. At that time she breaks out of the nest, and then both parents feed the young.

There is a regular association between hornbills and bands of monkeys in the treetops of African forests, with the birds seeking the insects stirred into activity by the fruit-eating monkeys.  Hornbills do not occur in the Americas where a similar ecological niche of medium-sized species is filled by Toucans.

Bucorvidae (Ground Hornbills), unlike the other hornbills, do not wall the female when nesting. They live in groups of 5 to 10 individuals including adults and juveniles. Often, neighbouring groups are engaged in aerial pursuits. They forage on the ground, where they feed on reptiles, frogs, snails, insects and mammals up to the size of hares. 

Hackett SJ et al (2008): Phylogenomic Study of Birds



coraciiforme (2011). Encyclopędia Britannica UltimateReference Suite Chicago,: Encyclopędia Britannica. Note that the above families were members of the older Coraciiforme order.