Eastern Yellow-billed Hornbill (Tockus flavirostris) [XC215425]
by id from Afar Plains, Ethiopia (call)
Eastern Yellow-billed Hornbill (Tockus flavirostris) [XC172864]
by Andrew Spencer from Qori Jabley area, Woqooyi Galbeed, Somaliland, Somalia (call)
Subspecies
Sometimes considered to form a superspecies with Southern Yellow-billed Hornbill (Tockus leucomelas), and in past usually treated as conspecific, but differs in voice and bare-part colours. Both are closely related to Von der Decken's Hornbill (Tockus deckeni), and also, more distantly, to Monteiro's Hornbill (Tockus monteiri) and Red-billed Hornbill (Tockus erythrorhynchus), based on similar calls and behaviour, and DNA studies. Slightly smaller birds from north-eastern Somalia described as subspecies somaliensis, mainly on basis of orange markings on bill, but this character apparently variable. Further study is required.
BirdLife International Species Factsheet