The Annual Cycle of Small Mammal Populations on a Zambian Floodplain

Abstract

Several species of rodents and shrews live on the Kafue River Flats when they are not covered by floodwaters. Mastomys natalensis is usually the most abundant. Pelomys fallax, Crocidura mariquensis, and C. occidentalis often are common in wet sites. Breeding begins late in the dry season and is at its height during the rains. Populations are built up at this time, and as floodwaters rise over a period of several months they are forced to the margins of the floodplain, where they sometimes form dense refugee populations. As the flood slowly recedes they follow it out, and by the end of the dry season the few surviving animals are confined largely to marshy areas near the river. Body weight and fat deposits decrease during the dry season. Live-trapping studies suggest that populations are unstable throughout the year, with few animals resident in an area for more than a few weeks. Small mammals adapt to the unstable environment of the Flats by moving about more than populations in more stable environments and by breeding rapidly when conditions permit