Small rodent ecology in two contrasting habitats : primary forest and a farmland in eastern Ghana
The ecology of small rodents was studied in Ghana on a farmland and in a primary forest that has been free from human interference for more than 100 years. The commonest species of rodent on the Farmland was Praomys natalensis which comprised 45.3 percent of the trappable population. In the Primary Forest the commonest species was Praomys stella which comprised 79.7 percent of the population. The Farmland supported a more diverse rodent fauna than did the Primary Forest. This is the first report of Steatomys cuppedius in Ghana. Both the estimated population density and standing crop biomass were higher for rodents living on the Fairmland than for those living in the Primary Forest. The species of rodents in both habitats showed seasonal changes in population sizes as a result of the effects of seasonal changes in rainfall, food availability, and variations in the influx of new individuals into the study area. Peaks in population sizes in most cases were mainly influenced by the influx of immigrants. The mean minimum longevity of the resident population in both habitats ranged from 3 to 4.2 months; and the survival rate estimates of most species were lowest during the major rainy season. Breeding in the Farmland rodents was possible, throughout the year with peaks towards the end of the rainy seasons. In the Primary Forest breeding in Praomys stella was also possible throughout the year but unlike the farmland rodents only a relatively small proportion (20-50 percent) of the adult females were pregnant or lactating in most months. Breeding in males in both habitats was continuous throughout the year and without any clear-cut seasonality. Praomys stella in the Primary Forest had the largest home range among the rodents studied. With the exception of Lophuromys sikapusi ull the rodents showed overlapping home ranges. In Lophuromys sikapusi home ranges of individuals of the same sexes did not overlap and on the basis of this and other evidence it has been suggested that Lophuromys sikapusi might have territory.