Experimental determination of the spatial scale of a prey patch from the predator’s perspective
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Foraging theory predicts that predators should prefer foraging in habitat patches with higher prey densities. However, density depends on the spatial scale at which a “patch” is defined by an observer. Ecologists strive to measure prey densities at the same scale that predators do, but many natural landscapes lack obvious, well-defined prey patches. Thus one must determine the scale at which predators define patches of prey. We estimated the scale at which guppies, Poecilia reticulata, selected patches of zooplankton prey using a behavioral assay. Guppies could choose between two prey arrays, each manipulated to have a density that depended on the spatial scale at which density was calculated. We estimated the scale of guppy foraging by comparing guppy preferences across a series of trials in which we systematically varied the scale associated with “high” prey density. This approach enables the application of foraging theory to non-discrete habitats and prey landscapes.
KeywordsForaging theory Patch selection Poecilia reticulata Density-dependent mortality Scale dependence
The authors would like to thank Matt Kon and Joanna Lewis for assistance with animal care. M. A. Birk would also like to thank Dr. Fredrick Scharf and Dr. Mark Galizio for being committee members of this thesis and Jesus Christ for this opportunity. This study was funded by the UNCW Department of Biology and Marine Biology and a UNCW Center for the Support of Undergraduate Research and Fellowships Research Supplies Grant. All research was conducted in accordance with all applicable laws and rules set forth by the USA and the UNCW Institutional Animal Care and Use Committee.
Conflict of interest
The authors declare that they have no conflict of interest.
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