![]() ![]() However, the bold black-and-white patterns of many forest hornbills and the delicate gray pied patterns of many Tockus species are far from dull. Horn-bill plumage is described as "drab," lacking the brilliant colors of relatives such as the kingfishers (Alcedinidae) and rollers (Coraciidae). Males are always larger and stouter than females but the greatest dimorphism often occurs in bill length with males having up to 30% longer bills. Hornbills vary tremendously in size and shape, starting with the large, long-legged southern ground-hornbill ( Bucorvus leadbeateri) weighing up to 13.2 lb (6 kg), and going down to the 0.26 lb (120 g) red-billed dwarf hornbill ( Tockus camurus). The oversized, slightly decurved bills topped by sometimes outlandish casques shaped as bumps, ridges, or horns make hornbills an unforgettable component of any landscape. Hornbills are among the most flamboyant birds of their habitat. Finally, hornbills have unusual kidneys in that they are two-lobed instead of three, and the Z chromosome, one of a pair of sex chromosomes, is oversized. All hornbills lack carotid arteries as well as the short feathers under the wings that cover the primary and secondary flight feathers of other birds. ![]() These include being blessed with long, sweeping eyelashes on their upper lids and a fusion of the first two cervical vertebrae to provide support for large bills. They found that ground-hornbills were probably the earliest form.Īll 54 hornbill species display unique anatomical features that clearly identify their affinities. Huebner and colleagues conducted detailed molecular studies of the two groups. The distinction between Bucerotinae and Bucorvinae is based on unique feather lice and anatomical and behavioral differences such as a greater number of neck vertebrae and the lack of nest-sealing behavior in the Bucorvinae. ![]() The exceptions are the terrestrial ground-hornbills, which fall within the subfamily Bucorvinae. All but two species are classified within the subfamily Bucerotinae. All birds of these families nest in tree holes, but only hornbills seal the entrance to their cavities.Īs of 2001, science recognizes 54 species of hornbills grouped within 14 genera and two subfamilies. This classification is based primarily on similarity in foot and jaw morphology, and a prolonged retention of quills by nestlings, which gives them a prickly "pin-cushion" look. Most modern taxonomic treatments place hornbills within the order Coraciiformes together with their closest relatives: the hoopoe (Upupidae) and the woodhoopoes and scimitarbills (Phoeniculidae). In his classic work The Hornbills published in 1995, Alan Kemp wrote "Trying to decide what other groups of birds are most closely related to hornbills is not quite so easy." Time has not made that decision any easier the classification of these bizarre, large-billed birds is still debated. Sub-Saharan Africa, south and Southeast Asia, New Guinea, and the Solomon Islands Evolution and systematics Medium to large-sized, stocky, highly vocal birds with long, slightly decurved bills topped by casques of various shapes, sizes, and colorsġ1.8–47.3 in (30–120 cm) 0.22–13.2 lb (100g–6 kg)Įndangered: 2 species Critically Endangered: 2 species Vulnerable: 5 species Near Threatened: 12 species ![]()
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