Patterns of diversity, species richness and community structure in West African small mammals (rodents and shrews).

Tropical savannah ecosystems are characterized by extensive grasslands withmore or less sparse trees and thickets, and are threatened globally by anthropogenicforces. These grassland habitats house a rich and diversified fauna assemblage, withsome of its conspicuous elements (for instance, small mammals) that have not beensufficiently investigated so far. In this paper, we meta-analyze the literature data availableon the community structure and diversity patterns of shrews and rodents in West Africansavannahs. Overall, 10,197 small mammal individuals belonging to 111 species ofRodentia and 55 species of Soricomorpha were found in the various studies carried outin the countries covered by the present study. Studies using a combination of methods(e.g., live trapping, pitfalls, cover boards, visual encounter) detected more species inboth Soricomorpha and Rodentia, and there was a positive survey (= trap / night) efforteffect on the species richness in rodents. GLM models showed (i) that there was also noeffect of trapping design (transect versus grid) on species richness per site, (ii) in bothrodents and soricomorphs, the number of savannah species by country depended on thetotal species richness of that given country, but there was no effect of the relative surfacecovered by savannahs in that country. The number of sympatric species per site was2.73±1.7 (range = 1-7) in Soricomorpha and 6.33±3.8 (range = 1-15) in Rodentia.Dominance index was significantly different among countries, with Nigeria having lowervalues than all other countries and Ghana, Benin and Sierra Leone had significantlyhigher values. The conservation implications of the observed patterns are discussed.