Foraging theory upscaled: the behavioural ecology of herbivore movement |
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Authors: | N Owen-Smith J M Fryxell E H Merrill |
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Institution: | 1School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Wits 2050, South Africa;2Department of Zoology, University of Guelph, 50 Stone Road E, Guelph, Ontario, Canada, N1G 2W1;3Department of Biological Sciences, University of Edmonton, Edmonton, Alberta, Canada, T6G 2E9 |
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Abstract: | We outline how principles of optimal foraging developed for diet and food patch selection might be applied to movement behaviour expressed over larger spatial and temporal scales. Our focus is on large mammalian herbivores, capable of carrying global positioning system (GPS) collars operating through the seasonal cycle and dependent on vegetation resources that are fixed in space but seasonally variable in availability and nutritional value. The concept of intermittent movement leads to the recognition of distinct movement modes over a hierarchy of spatio-temporal scales. Over larger scales, periods with relatively low displacement may indicate settlement within foraging areas, habitat units or seasonal ranges. Directed movements connect these patches or places used for other activities. Selection is expressed by switches in movement mode and the intensity of utilization by the settlement period relative to the area covered. The type of benefit obtained during settlement periods may be inferred from movement patterns, local environmental features, or the diel activity schedule. Rates of movement indicate changing costs in time and energy over the seasonal cycle, between years and among regions. GPS telemetry potentially enables large-scale movement responses to changing environmental conditions to be linked to population performance. |
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Keywords: | foraging areas GPS telemetry habitat units movement ecology seasonal ranges |
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