Abstract
Small mammals are an active component of ecosystems that supports energy and matter flows and they are responsible for both construction of and maintaining their habitat. Such activity is vital for human prosperity, as it supports the chemical and physical quality of the environment where the human is adapted as a biological species. The contemporary human activity has resulted in destruction of a number of natural habitats and, as a consequence, in drastic changes in the species abundance. Some species have become so abundant that pose problems for human health, agriculture, and industries. Some formerly common and even pest small mammals, on the contrary, have reduced in distribution and numbers and now fall in the category of vulnerable species. In both cases, ecologically-based management of populations is required to maintain an optimal abundance of various species. Effective ecologically-based management of populations could be based on the basic principles of population ecology. It implies our understanding of both external and internal factors affecting the population abundance. Here, I review some fundamental principles which could be applied to operational management of populations. Also, I focus on some specifics of population reactions which have been elaborated in the Russian ecological school. Based on the well-known principles of supporting the numbers of populations, I propose a classification of species in terms of their ability to provide and change the type of functions in local populations. My classification allows distinguishing three groups of species with predictable resilience of population. Fitted to various environmental instabilities, the species of these groups require different conservation tactics.