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Stopping rules for sit-and-wait foragers
Abstract
Patch depletion has been a dominant paradigm in foraging theory. However, most sit-and-wait foragers may not experience a declining rate of gain as a function of time spent in a foraging site. Hence my theme is not when to give-up, but rather, when to stay indefinitely. This is analogous to stopping problems in economic theory, that set a minimum acceptable rate given certain information about rates that may be encountered. I develop models that include as ecological variables the spatial distribution of sites, the moments of the site quality distribution, and the predictability and discriminability of site qualities. I compare the predictions of these models with the process of site selection by web-building spiders in the laboratory and by reviewing field studies. I include a discounting parameter as a general constraint in the models that may have several specific interpretations. I examine the consequences and reasons for discounting in an operant analogy to a stopping problem. In these experiments, blue jays search sequentially for food on a conveyor belt. A common result of these experiments and others is a lack of "self-control", defined as the tendency to pass up a smaller, immediate reward for a larger, delayed reward. Risk sensitivity in amount and delay may both contribute to this effect. I test for an interaction among these factors and discuss their relationship in various descriptive models. That these effects may occur both in poikilothermic spiders and homeothermic blue jays suggests their general importance, not only to foraging but in other search problems such as mate choice and habitat selection. I examine potential evolutionary consequences of these economic considerations in the trend towards decreasing site fidelity found in spiders. I apply the comparative method to focus on morphological specialization for prey capture by webs as a potential constraint on change in foraging mode.
Subject Area
Ecology|Operations research
Recommended Citation
Beachly, William Mardis, "Stopping rules for sit-and-wait foragers" (1996). ETD collection for University of Nebraska-Lincoln. AAI9703771.
https://digitalcommons.unl.edu/dissertations/AAI9703771