Spatially structured populations: how much do they match the classic metapopulation concept?

In the classic metapopulation concept a specific range of animal movements is assumed, not too large and not too small. Thus, knowledge of animal mobility is necessary to determine the degree to which a given population matches a specific metapopulation model. It seems that usually small mammal mobility is underestimated, and this has important consequences for the way we view metapopulation dynamics. Data on small mammal movements (Clethrionomys glareolus and Apodemus flavicollis) are presented in this paper. The material was collected in a two year study in western Poland using a set of six woodlots of different sizes and degree of isolation, located among agricultural fields. Various methods were used in the study: colored bait, live-trapping, and radio-telemetry. It is suggested that the populations under study match the concept of patchy population (sensu Harrison 1991), being poorly isolated in individual patches and with the range of animal movements encompassing the whole set of patches. Moreover, the use of patches changes between seasons according to changing needs and/or resource abundance in the woodlots. Density and composition of local populations may be influenced both by the patch area and its isolation, and also by the filtering effect of the matrix that depends on the season. In this context it is pointed out that more attention should be paid to the matrix, both in research practice and conservation as it is a factor influencing population functioning in quantitative and qualitative ways. It is suggested that any generalizations about population spatial organization may be impossible without more detailed knowledge of long distance movements of focal animals and their use of matrix.[PUBLICATION ABSTRACT]