Attention, 'apprehension' and gerbils searching in patches

In this paper, we consider the attentional demands associated with detectin g and responding to predators, or 'apprehension', and the within-patch sear ch of Allenby's gerbils, Gerbillus andersoni allenbyi. We, thus, present a first empirical investigation of the indirect, informational consequences o f perceived predation risk. Specifically, we focus on the ability to track the quality of seed patches in sandy habitats. There are two potential effe cts here; since instantaneous intake rate (or some proxy) is the key parame ter of interest to an optimal forager, apprehension can interfere with the estimation of: (1) the number of food items captured, and/or (2) the time t aken to capture them (the ability to locate food items). Only (2) will have a consistent effect on patch quality, and we test the hypothesis that incr eased predation risk reduces gerbil search efficiency. We therefore quantif ied gerbil search paths in patches of uniform seed distribution that differ ed in their associated risks of predation by manipulating the presence of b arn owls, Tyto alba, and light in an aviary. Gerbil search was more random under risky conditions. We discuss the implications of this result for info rmation processing and patch use under predation risk, and the foraging gam es between gerbils and owls in the Negev Desert.