The importance of population dynamics in heterogeneous landscapes: Management of vertebrate pests and some other animals

Abstract

Population dynamics is rarely considered in current pest control programs. Instead of the usual aim of killing a certain percentage of the target species, we demonstrate here the importance of considering dynamic aspects of populations when attempting management (e.g., pest control) of vertebrate populations. Conceptually we treat heterogeneous landscapes with pest-suitable patches intermingled with non-suitable areas. These pest-suitable patches are also regarded as separate objects for local pest management. We discuss density-independent and density-dependent natality and mortality rates for separate patches. In the landscape context we treat immigration into, and extinction in local patches. In this analysis we also consider the importance of transition habitats for local and regional population development.

We summarize our conclusions in a list of features which ought to be examined before a species' pest status can be evaluated and management programs are planned. Important information for such a purpose is the form and magnitude of natural mortality rates as functions of density, magnitude of equilibrium densities, the occurrence of presaturation dispersal or not, and the costs of reducing natality and of increasing mortality. Due to the immature state of population ecology, we emphasize that our suggestions have to be regarded as hypotheses to be tested in actual management situations.