Artificial watering points are focal points for activity by an invasive herbivore but not native herbivores in conservation reserves in arid Australia

Abstract

The spatial configuration of landscapes can be an important factor influencing the dispersal, distribution and abundance of invasive animals and consequently their impacts. In arid landscapes worldwide, humans have increased the availability of surface water by creating artificial water points (AWP) for livestock and wildlife viewing. The resource subsidy provided by AWP can influence the functioning of arid ecosystems by affecting the density, distribution and activity of water-dependent native and invasive animals and thus facilitate their trophic and competitive interactions. In this study, we used dung count indices to investigate the activity of an invasive herbivore, feral goats (Capra hircus), and native herbivores (kangaroos, Macropus spp.) in relation to surface water and habitat type in three conservation reserves located in arid Australia. Activity of feral goats showed a strong preference for rocky ranges habitat and decreased with distance from water. Kangaroo activity showed a strong preference for mulga woodlands, but was independent of distance from water. Our results suggest that artificial water points may exacerbate the impacts of feral goats by functioning as focal points for their activity. Restricting goats’ access to water by closure of water points or strategic fencing, such that the mean distance to water across the landscape is increased, may be an effective strategy to reduce goat grazing impacts in conservation reserves where natural sources of water are scarce but is unlikely to affect the grazing patterns of kangaroos. Our study suggests that there is scope to control populations of water-dependent invasive vertebrates in arid regions by restricting their access to artificial water points.