Modelling the spatial distribution of mammals

Abstract

In this thesis I outline the different processes, operating at different scales, that influence the spatial distribution of mammals and review modelling approaches that have been used to represent these processes. I investigate the application of a selection of modelling approaches operating at different scales. A model based on the energetics and movements of individual foragers was developed to investigate population spacing patterns and applied to the red squirrel. At high food densities, small, similarly sized, non overlapping ranges were generated, whereas at low food densities ranges were larger, more overlapping and more variable in size. The model is a first step towards investigating the spacing patterns of ranging mammals. A model representing the positioning of dens was applied to predict the distribution of badger main setts. The model determined how many setts could be placed in suitable habitats while maintaining a pre-defined, minimum inter-sett distance. The representation of badger spacing behaviour and the utility of the approach is discussed. At a larger scale, a model based upon births and deaths within habitat patches and an explicit representation of dispersal between patches was used to assess plans to reintroduce the beaver. It predicted little or no population spread, in contrast to the application of a generic population viability analysis package that predicted rapid population spread. A difference in the representation of dispersal was identified as the most likely cause of the disparity. A general model based on these approaches was developed to investigate the interaction between dispersal and demographic processesing spatially explicit population models. The future of models to predict the spatial distribution of mammals is discussed in relation to issues of scale, management applications and modelling philosophies.