Population ecology of rodents of maize fields and grassland in central Ethiopia

We report on the presence of rodents in grassland and maize fields in central Ethiopia, during the course of a 21-month study by means of removal and capture-recapture trapping. In both habitats, the small mammal fauna consisted of the same species but in different relative proportions: Arvicanthis dembeensis, Mastomys erythroleucus, Tatera robusta, Rattus rattus, Mus mahomet and Crocidura olivieri. A. dembeensis and M. erythroleucus were the dominant species. Densities were generally low throughout the study period, but at the end of the breeding season in the second year of the study, the numbers of A.dembeensis reached high values in the grassland. Breeding was seasonal and related to rainfall periods: extended rainy seasons resulting in longer periods with breeding females and higher litter sizes and, consequently, population size increases. These observations suggest that rodent population dynamics in the study area are linked to rainfall patterns and this information can be used to develop forecasting models.