Effects of an experimentally clumped food resource on raccoon Procyon lotor home-range use.

Some species of carnivores fluctuate between a primarily solitary lifestyle and a group-living lifestyle, depending on resource availability. Understanding the ontogeny of this transition requires analyzing changes in space use. We analyzed radio-telemetry data from 41 adult raccoons Procyon lotor to assess the influence of an experimentally maintained clumped food source on spatial structure. We compared home-range size, two-dimensional overlap and volume of intersection (VI) values between 22 raccoons with access to the clumped food resource and 19 raccoons on an adjacent control site that received similar food quantities, but for which food was distributed in a non-clumped and spatially-temporally unpredictable pattern. No between-sex differences in home-range size occurred within either food site, nor did differences in home-range size occur between the two sites. However, the experimental-site animals had two-dimensional home-range overlap values and volume of intersection (VI) scores that were nearly twice those of raccoons inhabiting the control site. These differences appear to be driven by increased overlap among females from the experimental site, as males from the two treatment sites had similar home-range overlap and VI scores. Collectively, these results indicate that the distribution of resources can significantly change the extent of spatial overlap among individuals, even when the mean home-range size of the population does not change. This further suggests that while a site's overall resource availability influences population size, the spatial clumping of resources facilitates the formation of local aggregations. [ABSTRACT FROM AUTHOR]