Effects of seasonality and changes in vegetation structure on small mammal populations in three distinct habitats

As seasons change so do the characteristics of plants, such as amount foliage and density of grasses, which affects the populations of mammals dependent on the food and cover provided by the vegetation. By comparing data collected between 14 and 16 September 2009 to previously collected data between 11 and 14 April 2009, we were able to explore the effect of seasonality on small mammal populations within three study zones in Mapungubwe National Park, South Africa. The three study zones represented three different habitats and were a camp dominated by man-made structures interspersed with Mopane trees, an open grassy area with some shrub cover, and a cliff area consisting of bare rock face and grass cover. Comparison of the data revealed a significant drop in abundance of rodents in the winter at the human disturbed and grassy sites but not in the rocky site. It was also noted that although abundance decreased overall from winter to summer, both species diversity and richness increased. Finally, differences in community structure were noted, in particular an increase from summer to winter in Mastomys natalensis and Tatera leucogaster. Possible explanations for these differences involve a combination of: (1) differences in vegetative cover brought on my changes in season; (2) food scarcity bringing out trap shy rodents; (3) a decrease in inter-species competition due to decreased species dominance in winter.