The Characteristics of Rat Populations

Abstract

Data from various sources are assembled to facilitate understanding of natural populations. Changes in populations are often predictable from a sigmoid curve, but variation in conditions causes each population to have its own particular curve. Reproduction as a population force varies much less from place to place and time to time than does mortality, although data on the latter are meager, and this fact emphasizes importance of mortality studies. Habitat is fundamental in determination of population size, but density dependent factors, predation and competition are means of holding population within limits imposed by habitat. For rats, competition as manifested by social organization is more frequent mechanism for limiting population and therefore merits increased attention.