Giving Up Density
About the Module:
In this module, students explore animal foraging choices through Giving Up Densities (GUD), an integrative measure of animal condition, habitat quality, and the landscape of fear. GUD is very easy to measure experimentally – it is literally the amount of food left in a patch when an animal abandons it. However, its interpretation is a bit more complex: it integrates the value of a food item (relative to the quality and availability of other food in the environment), the animal’s physiological condition (energy demands), and environmental risks (e.g., perceived predation pressure or competition). In other words, GUD helps us understand animal foraging decisions because it indicates the cost-benefit ratio of foraging at that patch: lower GUD indicates a lower net cost and/or a higher benefit of the food items in the patch. The integrative nature of GUD allows students to test a broad range of hypotheses about how foraging decisions of squirrels may be related to biome/habitat type (urban vs non-urban, for example), microhabitat (cover vs. no cover), proximity to human structures (like sidewalks or buildings), species type (diurnal squirrels vs. nocturnal rodents), and other factors (like artificial light, predator scent/decoys, sound or moon phase).