Population Cycles in Small Mammals

This chapter summarizes the current information on population cycles in small rodents, and first looks at the general questions about cycles, and then discusses the demographic machinery which drives the changes in numbers.

Abstract

This chapter summarizes the current information on population cycles in small rodents. It first looks at the general questions about cycles, and then discusses the demographic machinery which drives the changes in numbers. And finally, analyzes the current theories which explain population cycles in rodents. Population cycles in voles and lemmings are accompanied by a series of changes. A few of them include fluctuations occurring in a variety of genera and species from arctic to temperate areas, from Mediterranean to continental climates, from snowy areas to snow-free areas. Populations living in a wide variety of plant communities in a small geographic area all fluctuate in the same way, often in phase. Survival of adult males fluctuates independently of that of adult females, when viewed on a weekly time scale. Males may suffer heavy losses in the decline for a few weeks when females are surviving very well, and vice versa.