A framework for testing assumptions about foraging scales, body mass, and niche separation using telemetry data

Cumming, Graeme S., Henry, Dominic A.W., and Reynolds, Chevonne (2017) A framework for testing assumptions about foraging scales, body mass, and niche separation using telemetry data. Ecology and Evolution, 7 (14). pp. 5276-5284.

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Ecological theory predicts that if animals with very similar dietary requirements inhabit the same landscape, then they should avoid niche overlap by either exploiting food resources at different times or foraging at different spatial scales. Similarly, it is often assumed that animals that fall in different body mass modes and share the same body plan will use landscapes at different spatial scales. We developed a new methodological framework for understanding the scaling of foraging (i.e. the range and distribution of scales at which animals use their landscapes) by applying a combination of three well-established methods to satellite telemetry data to quantify foraging patch size distributions: (1) first-passage time analysis; (2) a movement-based kernel density estimator; and (3) statistical comparison of resulting histograms and tests for multimodality. We demonstrate our approach using two sympatric, ecologically similar species of African ducks with quite different body masses: Egyptian Geese (actually a shelduck), and Red-billed Teal. Contrary to theoretical predictions, the two species, which are sympatric throughout the year, foraged at almost identical spatial scales. Our results show how ecologists can use GPS tracking data to explicitly quantify and compare the scales of foraging by different organisms within an animal community. Our analysis demonstrates both a novel approach to foraging data analysis and the need for caution when making assumptions about the relationships among niche separation, diet, and foraging scale.

Item ID: 50664
Item Type: Article (Research - C1)
ISSN: 2045-7758
Keywords: body size, dispersal, hierarchy, movement, multimodality, scale, scaling, southern Africa
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This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Funders: National Research Foundation (NRF), South Africa, Percy FitzPatrick Institute, James S. McDonnell Foundation (JSMF), University of Cape Town, Wildlife Conservation Society, ARC Centre of Excellence for Coral Reef Studies
Date Deposited: 20 Sep 2017 10:57
FoR Codes: 31 BIOLOGICAL SCIENCES > 3103 Ecology > 310302 Community ecology (excl. invasive species ecology) @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 100%
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