Differences in abundance and species richness between shrews and rodents along an elevational gradient in the Udzungwa Mountains, Tanzania

Small mammals (shrews and rodents) were surveyed along an elevational transect in the Udzungwa Scarp Forest Reserve, in the Udzungwa Mountains, Tanzania. Trap lines and pitfall lines were installed at 600, 910, 1460, and 2000 m a.s.l. In a total of 10341 sample nights (7448 trap-nights and 2893 bucket-nights) 343 specimens (148 shrews, 205 rodents) were captured representing 9 shrew and 14 rodent species for a total of 23 species. While overall species diversity generally increased with elevation, this pattern was not constant for each group sampled. For rodents, both species richness and abundance were lowest at 600 m and greatest at 2000 m a.s.l., and were significantly correlated with elevation. While the highest species number and abundance for shrews was at 2000 m, there was no correlation of these two values with elevation. Rainfall appears to have affected the capture of shrews, but not rodents, and capture success of individual buckets and traps indicated a lack of capture independence. Eastern Arc endemics such asCrocidura desperata Hutterer, Jenkins and Verheyen, 1991 andMyosorex kihaulei Stanley and Hutterer, 2000 were more abundant at 2000 m a.s.l., than at lower elevations. Implications of results of this survey for analyses of future biotic surveys are discussed.