Response of vertebrates to fenceline contrasts in grazing intensity in semi-arid woodlands of eastern Australia

Changes in the abundance, species richness and assemblage composition of vertebrates due to grazing by domestic stock were investigated in the semi-arid woodlands of eastern Australia. Analyses were based on the differences found at 10 fenceline contrast sites. Two species of amphibians, 22 species of reptiles and two species of small mammal were captured in pit traps during the surveys. Kangaroos (red and eastern grey), sheep, goats and 66 species of birds were recorded along line transects. Analyses revealed that abundance of diurnal reptiles and species richness of diurnal reptiles and birds were significantly lower on heavily grazed sites than they were on lightly grazed sites. At a local scale, the gecko, Gehyra variegata, was more abundant where grazing was heavier, while Diplodactylus conspicillatus, Diplodactylus steindachneri and Rhynchoedura ornata responded to variables indirectly related to grazing intensity (kangaroo density, sheep and goat dung mass and sheep density, respectively). Birds more commonly sighted on lightly grazed areas than heavily grazed areas were the apostlebird, brown treecreeper, crested bellbird, grey butcherbird, hooded robin, jacky winter, little woodswallow, Australian magpie-lark, mulga parrot, splendid wren, white-browed treecreeper and yellow-rumped thornbill. Birds more commonly sighted on heavily grazed areas than on lightly grazed areas were the Australian raven and chestnut-crowned babbler. Most variation in species composition between sites was due to spatial separation and no regional-level indicator species of grazing were evident. A combination of direct grazing-related changes (e.g. loss of ground cover) and indirect effects of the pastoral industry (e.g. introduction of artificial sources of water) lead to changes in fauna at different scales of analysis across regions.