The effect of habitat type on rodent, shrew and sengi species abundance, richness, diversity and composition at farm Karachas, Outjo, Namibia

Natural habitats have been fragmented by many human activities including farming, hence affecting vegetation structure. Despite being very dry, Namibia has many farms in which game, livestock and crop farming are practiced. Yet such activities affect populations of many other organisms including small mammals such as rodents, shrews and sengis. The present study investigated the effect of habitat type on rodent, shrew and sengi species abundance, richness, diversity and composition in selected open grassland habitat and woody habitats at Karachas Farm, Outjo, Namibia. Sampling at each habitat type was replicated twice. Woody plant species abundance, composition, height and percentage grass cover were determined and compared between the open grassland and woody habitats. A capture-mark-recapture (CMR) technique was employed to obtain data on rodents, shrews and sengis. Each habitat type was sampled over five consecutive nights using Sherman live traps. The result of t-, chi-square and Mann-Whitney tests, respectively, showed a statistically significant difference in the mean abundance of woody plants, plant height, and plant species richness between the open grassland and woody habitats. A Mann-Whitney test showed no statistically significant difference in the percentage grass cover between the open grassland and woody habitats. A Hierarchical Cluster Analysis (HCA) based on a Bray Curtis Similarity Index showed a low (31%) level of similarity in woody plants species composition between the open grassland and woody habitats. A total of 800 trap-nights yielded 145 individuals comprising 6 rodent red veld rat (Aethomys chrysophilus), namaqua rock mouse (Micaelamys namaquensis), bushveld gerbil (Gebilliscus leucogaster), maltimammate mouse (Mastomys natalensis), tree mouse (Thallomys paedulcus), pouched mouse (Saccostomus campestris), sengi (Elephantulus intufi) and shrew (Crocidura hirta) species. t- tests and a Mann- Whitney test, respectively, showed no statistically