The red-billed hornbills are a group of hornbills found in savanna and woodland of sub-Saharan Africa. They are now usually split into five species, the northern red-billed hornbill (T. erythrorhynchus), western red-billed hornbill (T. kempi), Tanzanian red-billed hornbill (T. ruahae), southern red-billed hornbill (T. rufirostris) and Damara red-billed hornbill (T. damarensis), but some authorities considered them all to be subspecies of a single species.
This group of conspicuous birds have mainly whitish underparts and head, grey upperparts, long tails, and a long and curved red bill which lacks a casque. The sexes are similar, but the female has a smaller bill. They are generally large, at 42 centimetres (17 in) long, but the entire group is considered as one of the smaller hornbills. source