Despite this, there are major differences between the habitat and climates in the core areas of the subspecies' distributions, and it is likely that each has specific genetic or behavioral adaptations to its environment. For this reason, conservationists sometimes refer to the black rhino subspecies as ecotypes, but in this Action Plan the term subspecies is used. This is the rarest and most endangered subspecies of black rhino. Once ranging through the savannah zones of central-west Africa, only a few scattered animals now remain in northern Cameroon. A few western black rhinos may remain in Chad, although this is unlikely, and is yet to be confirmed.
Numbers continue to decline and the subspecies is threatened with extinction in the near future.
Most of the remaining animals appear to live in small groups that are widely scattered and may not be in breeding contact. This subspecies has longer, more slender and more curved horns than the two southern subspecies, and is reputedly more aggressive. Historically this subspecies was distributed from southern Sudan, Ethiopia, and Somalia through Kenya into northern-central Tanzania. Its current stronghold is Kenya. Small numbers are still to be found in Rwanda and Tanzania, but its presence in Ethiopia needs confirmation.