Experimental manipulation of litter suggests that mice find dense litter more difficult to forage in ( Bachen et al. Often, small mammals exhibit declines in abundance as cheatgrass invades, but the mechanisms behind these shifts in abundance remain unclear. 2001 Melaschenko 2010 Ceradini and Chalfoun 2017). This line of thinking becomes important in the context of understanding how native herbivores and omnivores respond to invasive plant species that change both cover and food supply.įor example, native mouse species in western sage-steppe environments of North America exhibit complex and varied changes in abundance in relation to invasion by cheatgrass ( Bromus tectorum- Gano et al. 2019), and individual condition ( Dicke and Burrough 1988 Crist et al. 2019), population density ( Delciellos et al. Movements of animals are shaped by many features of their environment, including distribution of cover and food ( Hodges 1999 McIntyre and Wiens 1999), habitat structure ( Ceradini and Chalfoun 2017), perceived risk of predation ( Lima and Dill 1990 Stoddard et al. Collectively, our results indicate that foraging movements of pocket mice were not affected by the low densities of cheatgrass in this system.Ĭheatgrass, foraging, habitat selection, movements, pocket mouse, tortuosity The fractal dimension of movement pathways of pocket mice was consistent over spatial scales ranging from 0.5 m to two-thirds of the home range size, unlike in other species where fractal dimensions are not consistent over multiple spatial scales. The pathway tortuosity (fractal D) of pocket mice increased with vegetative cover and population density and decreased with open habitat, but these variables explained little of the variation in tortuosity. We examined the movements of Great Basin pocket mice ( Perognathus parvus) in sage-steppe habitats invaded by cheatgreass ( Bromus tectorum) in southcentral British Columbia, Canada. Invasive plants may alter habitat structure and provide novel foods thus, measuring how animals forage in invaded landscapes offers insights into these new ecological relationships. Foraging animals choose habitats based on characteristics that often cannot be satisfied simultaneously, such as easy mobility, abundant or high-quality foods, and safety from predators.
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