The northern red-billed hornbill (Tockus erythrorhynchus) is a species of hornbill in the family Bucerotidae. It is found from southern Mauritania through Somalia and northeast Tanzania. There are five species of red-billed hornbills recognized, but all five were once considered conspecific and some authorities still classify the others as subspecies of Tockus erythrorhynchus.[2]
^"Red-billed Hornbill". www.hbw.com. Handbook of Birds of the World online. Retrieved 12 May 2018.
Kemp, A.C. and W. Delport. 2002. Comments on the status of subspecies in the red-billed hornbill (Tockus erythrorhynchus) complex (Aves: Bucerotidae), with the description of a new taxon endemic to Tanzania. Annals of the Transvaal Museum 39: 1–8.
Delport, W., A.C. Kemp, and J.W.H. Ferguson. 2004. Structure of an African Red-billed Hornbill (Tockus erythrorhynchus rufirostris and T. e. damarensis) hybrid zone as revealed by morphology, behavior, and breeding biology. Auk 121: 565–586.
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