The Relationship of the Southern Nigerian Avifauna to Those of Upper and Lower Guinea

Summary. The composition of the forest avifauna of Southern Nigeria is analysed in the light of the most recent work in the region. It is found that east of the Niger the affinities are with Lower Guinea: at Lagos with Upper Guinea; in the Ondo‐Benin area not definitely with either. A discussion of the barriers between the two sub‐regions follows, and it is claimed that, whereas the Lagos‐Accra savanna gap and the Cameroon montane area can each account for about one quarter of the total change, factors within Nigeria were almost twice as important in causing differentiation. It is suggested that these factors were a combination of climatic conditions and northward position of the coastline in late or post‐Pliocene times, giving rise to a condition similar to that we find today between Lagos and Accra.