Diversity and distribution of murid rodent populations between forest and derived savanna sites within south western Nigeria

Southward encroachment of the derived savanna zone with its attendant denudation of the rainforest in Nigeria adversely affects the diversity and distribution of mammals, particularly murid rodents. This study was carried out to establish the identities of murid rodent populations and to compare their diversity between forest and derived savanna sites within south western Nigeria. Identification of captured specimens was carried out by multivariate statistics of body and skull measurements, and also by analysis of certain discrete characters. Six species were identified: Praomys tullbergi, Hylomyscus stella, Mastomys natalensis, Arvicanthis rufinus, Lemniscomys striatus and Lophuromys sikapusi. Forest sites possessed a higher Shannon's diversity index (1.685) than the derived savanna sites (0.978), containing a higher number of taxa and larger abundance of murid rodents. This underscores the negative impact that encroachment of the derived savanna has upon diversity of animals in areas that were once forest.