On animal distributions in dynamic landscapes

Few landscapes are static and patterns of resource distribution can vary markedly in time and space. Patterns of movement and dispersal in response to environmental change are equally diverse and occur on a broad range of temporal scales. For patterns of movement and dispersal that vary spatially and temporally throughout the life-time of an individual, the concepts of home range and geographic range alone do not adequately describe the observed patterns of distribution of individuals, populations or species. Here we further simplify Gauthreaux (1982) classification of movement types into a simple bipartite system and link movements (or lack thereof) to a similarly simple classification of ranges. In addition, we introduce two new indices that describe the relationship of an individual's life-time movements to its distribution as described by home and geographic range. Our interest in this subject arose from endeavouring to interpret local changes in waterbird abundance in the arid interior of the Australian continent and to understand these changes in relation to patterns of resource distribution and movement. In this discussion we focus on terrestrial vertebrates capable of multiple breeding events throughout an extended life-time.