Hungry and Afraid: The effects of starvation on the foraging behavior of Panopeus herbstii in the presence of a higher-order predator

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Hughes, Jennifer
- Affiliation: College of Arts and Sciences, UNC Institute for the Environment

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This study utilizes an experimentally simulated three-tiered trophic chain between Menippe mercenaria (stone crabs), Panopeus herbstii (marsh mud crabs), and juvenile Mercenaria mercenaria (quahog clams), to analyze the influence of hunger on mesopredator foraging behavior in the presence and absence of a higher-order predator as predicted by principles of the ecology of fear and the optimal foraging theory. A 2x2 factorial design utilizing P. herbstii that were subjected to 7-day starvation or fed 30 minutes before the each experiment in combination with or without a stone crab, or a “fear factor,” was used to analyze biomass consumption and prey size selection differences influenced by hunger and fear response. The optimal size class of juvenile clams selected was also predicted by generating a curve of net kcal gained during experiments by subtracting kcal expended during crushing from kcal of soft tissue ingested for each size class of clam. Results suggest that 7-day starvation does not significantly increase consumption in the presence of fear (p=0.485), but fear does significantly affect prey biomass consumed (p=0.0175) and prey size selectivity (p<0.0001). Foraging practices deviated from optimal foraging predictions, indicating a wider range of factors outside of energy to crush this prey species—such as search time, ability to manipulate prey of different sizes, etc.—should be taken into consideration when formulating predictions of optimal prey size.

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	Thesis	2019-05-17	Public	Download