Document: MIC-3-99-139

Relative influences on foraging: The gerbil's perspective.

ABRAMSKY, Z.* ¹ and M.L.ROSENZWEIG ²

Ben Gurion University of the Negev, Beer-sheba Israel ¹
University of Arizona, Tucson, AZ 85721 USA ²

Abstract:
Many variables determine the profitability of foraging. These include food supply, habitat, intraspecific competition, interspecific competition, and the threat of predation. Instead of measuring these variables, we have asked gerbils, Gerbillus allenbyi Rodentia, in 1 ha paired field enclosures to convert them all to the common currency of millet seeds. We add the millet seeds in various quantities (0-48g/tray/night) mixed with large amounts of sand in 18 trays/ha. Gerbil behavior tells us when we are adding seeds at a rate sufficient to neutralize the experimental differences in the variables between our two experimental subplots. The strongest effects come from predation threats. The weakest, only about 1/10 as strong as predation's effects, come from differences in micro-habitat. This is so, despite the fact that our previous work suggests that these gerbils depend upon the micro-habitat differences to survive the competition of a larger congener, G. pyramidum.

Keywords: foraging

This abstract is being presented at: 9:45 AM in session:
Oral Session #21: Small Mammal Population Ecology.