Factors affecting gerbil foraging behavior and rates of owl predation

Experimented on how illumination, habitat structure, and three different species of owls affected the foraging behavior of Gerbillus allenbyi and G. pyramidum, which coexist on sand dune habitats in the Negev Desert, Israel. In response to the presence of owls or to increased illumination, gerbils foraged less, shifted foraging activity to the bush microhabitat, and quit patches at a higher giving-up density of resources. In accord with moonlight avoidance, both gerbil species suffered higher predation rates under illumination. G. pyramidum distinguished among owl species, as indicated by changes in patch use and habitat selection. Gerbils foraged less in the open than in the bush microhabitat, foraged less when there was no cover present, and foraged less in the bush microhabitat when patches were encumbered by entangling branches. In accord with avoidance of open areas, both gerbil species suffered higher rates of predation when shrub cover was 0% than when shrub cover was 10%. With 0% cover, G. allenbyi suffered higher predation rates than G. pyramidum, but with 10% cover, rates of owl predation did not differ between gerbil species. Relative to G. allenbyi, G. pyramidum predominates on open sand dunes and biases its behavior toward the open microhabitat. -from Authors