White-crested Hornbill (Horizocerus albocristatus) [XC531739]
by Marc Languy from Ouesso, Sangha, Congo (Brazzaville) (song)
White-crested Hornbill (Horizocerus albocristatus) [XC671644]
by \u00c9tienne Leroy from Bakoumba, Lekoko, Haut-Ogooue, Gabon (uncertain)
Subspecies
Often placed in genus Tockus, or occasionally in Berenicornis, but appears to be sufficiently distinct in behaviour and voice, as well as in some aspects of morphology, to merit treatment in monospecific genus.
The following 3 subspecies are recognised:
albocristatus (Cassin, 1848) - Southern Sierra Leone, southern Guinea, Liberia and western Ivory Coast.
macrourus (Bonaparte, 1850) - Eastern Ivory Coast to Benin.
cassini (Finsch, 1903) - Nigeria east to western Uganda, south to northern Angola. Considered by some authors to be a distinct species, Eastern Long-tailed Hornbill (Horizocerus cassini).