A population study on small rodents in the tropical rain forest of Nigeria

Abstract

Ecological research on African rodents in the last few years concentrated on geographical distribution, species composition, feeding preferences and reproductive biology (Delany 1972). The emphasis on these tapies has been due to the relatively small amount of research on African rodents, the enormous variety of species, and the large size and ecological diversity of the African continent. Population studies have been almost entirely neglected, although there are some recent studies on population fluctuations, age structure of populations, and mechanisms for population regu­ lation. ln the arid zone, Poulet (1972) has described the population changes of Taterillus pygargus in Senegal, and Happold (1967) gave some data on the population structure of Jaculus jaculus at diff erent times of the year in the Sudan. ln the savanna, Anadu (1973) followed the population fluctuations of Myomys daltoni and Mus musculoides in the derived savanna of Nigeria, and Neal (1970) showed how the populations of several species in Uganda changed during the course of the year in relation to annual fires. Bellier (1967) in the Ivory Coast, and Dieterlen (1967) in the highland grasslands of Kivu (Zaire) have given data on biomass and how this changes during the course of the year. The only study of rodent populations in moist evergreen forest known to me is that of Delany (1971) who related the population structure of several species in Mayanga forest Uganda (annual rainfall 1250 mm) to variations in the reproductive rate. None of these studies lasted for more than three years. An obvious gap in our knowledge is how rodent populations in Africa (whether in rain forest, savanna or arid regions) fluctuate over long periods of time, and the magnitude of population changes.