ABSTRACT
This chapter describes principles that are useful to direct the kind of effort and to evaluate the results. The number of rodents in an area reflects the conditions of the environment. The population reaches a level called carrying capacity which is defined as the number of rodents the habitat supports. The number of rodents in an area may remain the same for short or long periods of time. The number of rodents will adjust a new level dictated by the changed conditions. The number of rodents is limited by the quantity of some resource such as food or shelter, or some interaction such as parasites or social relations. A population, through the processes of regulation, adjusts to this limit and will remain at that level until conditions change. In rodents and many other animals the most pervasive density-dependent factor is social behavior.
