The biological complexity and interdependence of species of tropical forests is commonly referenced, but only just beginning to be understood. The best conservation strategy can be achieved with knowledge of species’ ecology. Unlike other vertebrate groups like birds, the biology of the small mammals of the central African countries is poorly known. Basic data like species numbers, population densities and habitat requirements are not available.

African Dormouse Graphiurus murinus

There is no species list for the small mammals that occur in Bwindi Impenetrable National Park (BINP). Of the sixty species of small mammals that had been listed for BINP by Butynski (in 1984), fifteen were labelled “probable” (that is, suspected to occur but not observed during the survey). BINP needs more detailed attention for its small mammal fauna.

This study aimed at; 1) identifying small mammals and estimating their densities and biomass, 2) assessing seasonal changes in spatial distribution of small mammals and 3) assessing small mammal biomass and density fluctuations in relation to environmental factors. Two Sherman and three Havahart trap sizes, as well as pitfall traps were used for trapping. These traps were set up in three study plots which were located between altitudes 2,118m and 2,263m above sea level. The study plots were divided into closed canopy, sparse canopy and open canopy plots, depending on the vegetation structure. A grid of 10 x 10m was established in each of the three plots and sampled monthly, between April and September 1992. 52 trappings were made in each plot. Total number caught and direct enumeration methods were used to estimate the population size of the small mammals. The differences in community composition and species diversity indices were described in relation to different vegetation structure.

A total of 1232 rodents (15 species) were recorded in 5747 captures. 5 insectivores were also caught. The open canopy forest recorded the highest number of rodent species (14), while the closed canopy recorded the lowest (8). 11 species of rodents were recorded in the sparse canopy forest.  Trapping results revealed that 9 species of small mammals were entirely terrestrial, 6 scansorial (climbing species) and 3 arboreal. Shannon-Wiener and Simpson Species diversity indices were highest in the sparse canopy forest and lowest in the closed canopy forest.  

The author concludes by recommending that further research into the ecology of small mammals in different parts of the park is necessary since this had been the first of a kind in BINP.