Hornbill mothers wall themselves into nest holes
Tropical Africa, Asia, and Melanesia host about sixty-two living Bucerotidae species defined by massive down-curved bills, often topped by a hollow casque. Breeding females of most species seal themselves inside tree cavities, accepting food only through a slit until the chicks grow.
Size spans the black dwarf hornbill at roughly 99 grams and 32 centimetres to the southern ground hornbill among the heaviest. Toucans fill a similar niche in the Neotropics by convergent evolution, not close kinship. No genus spans both Africa and Asia. Indonesia holds thirteen species by IUCN counts; the Philippines' eleven endemics are among the most threatened. Roosts can gather as many as about 2,400 birds. Hornbills see binocularly past their own bill tip, aiding precise food handling.
They are omnivores that toss food from bill tip to throat because tongues are too short to rake it back. Forest fruit specialists disperse seeds; some favour strychnine-tree fruits despite the poison. Before laying up to about six white eggs, Bucerotinae females—sometimes helped by males—plaster nest entrances with mud, droppings, and fruit pulp until only a feeding slit remains. Inside, the female undergoes a complete simultaneous moult. When space runs out she breaks free; chicks may rebuild the wall. Ground hornbills skip the sealing ritual.
African species sometimes forage with dwarf mongooses, trading mutual alarm calls, or trail monkeys for flushed insects. Family name Bucerotidae traces to Linnaeus's Buceros—'ox horn'—formalised by Rafinesque in 1815. Genetics hint that ground hornbills and Bycanistes form an early African clade while most other lineages diversified in Asia. Fossil hornbills from late Miocene Morocco and Bulgaria show a once wider African-European range; the oldest known fossil is from Early Miocene Uganda about nineteen million years ago.
Source: Hornbill
