African Hornbills will not win any beauty contests, but their odd anatomy and behavior makes them quite interesting.
But the upper mandible is actually hollow and relatively light-weight. Nevertheless, to strengthen the appendage for its intended uses (nest building, fighting, catching prey), the hornbills’ first two neck vertebrae are fused and their neck muscles greatly strengthened. Strangely, Hornbill tongues are much shorter than their elongate bill, so the birds deftly pick up food bits with the tip of the bill and toss it back into their mouth with a backward flick of their head.
A close relative of the Yellow-billed Hornbill, the Red-billed Hornbill, has been immortalized as the character Zazu, in the Lion King movie.
Both Red- and Yellow-billed Hornbills were common in the acacia scrub-desert environment of Southern Africa, and they share, along with other Hornbill species, similar eating habits (omnivores that eat whatever they can find) and nesting habits.
After the pair excavate a suitable roost in the tree, the female climbs in, molts all of her feathers, seals herself in with her feces and mud brought by the male, leaving only a tiny slit through which he will feed her for the next few weeks as she incubates the eggs and broods the chicks. It must get pretty hot and stuffy in there, but the chicks are well protected from predation.
There are 55 species of Hornbills spread over Africa and the Indian sub-continent, all sharing the hollow casque structure of the upper mandible and unusual nesting behavior of the female (sealed into her little tree prison). The largest, and probably ugliest of them all, is the Ground Hornbill, a species endemic to sub-Saharan Africa.
They are very long lived, reaching 60 years, and only breed every couple of years, depending on the conditions. Two eggs are laid In a burrow (they can’t dig themselves) but only one chick is usually reared, because they hatch many days apart, and the older one usually eats the younger chick.