Response of Deer Mice (Peromyscus maniculatus) to shrubs in shortgrass prairie: Linking small-scale movements and the spatial distribution of individuals

Abstract

1. Organisms respond to the abundance and spatial distribution of resources at both individual and population scales but there have been relatively few attempts to link insights from studies of these different phenomena, especially for wide-ranging vertebrates. 2. Deer Mice (Peromyscus maniculatus) were live-trapped and tracked across a gradient of shrub cover in shortgrass prairie to determine patterns of abundance, microhabitat use and movements. 3. In areas with few shrubs, mice preferred shrub microhabitats and their movement trails were relatively straight. Both trail tortuosity and population density increased with increasing shrub cover, so that mice tended to accumulate in areas where their trails were most convoluted. However, movements were also linear where shrubs were dense, presumably because mice could achieve the benefits of association with shrubs without travelling directly beneath them. Areas with dense shrubs also had high but variable population densities, suggesting that other factors such as intraspecific interactions may have affected movements on a larger, home-range scale. 4. Apparent thresholds in the selective vs random use of shrubs, movement patterns and abundance occurred over a narrow range of shrub cover where shrubs were most aggregated, underscoring the importance of both shrub density and dispersion. Nonlinear relationships in the response to resources at both behavioural and population scales thus may complicate our ability to predict abundance from individual movements across a broad range of resource distributions.