Utility of stable isotope analysis in studying foraging ecology of herbivores: Examples from moose and caribou

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Recently, researchers emphasized that patterns of stable isotope ratios observed at the individual level are a result of an interaction between ecological, physiological, and biochemical processes. Isotopic models for herbivores provide additional complications because those mammals consume foods that have high variability in nitrogen concentrations. In addition, distribution of amino acids in plants may differ greatly from that required by a herbivore. At northern latitudes, where the growing season of vegetation is short, isotope ratios in herbivore tissues are expected to differ between seasons. Summer ratios likely reflect diet composition, whereas winter ratios would reflect diet and nutrient recycling by the animals. We tested this hypothesis using data collected from blood samples of caribou (Rangifer tarandus) and moose (Alces alces) in Denali National Park and Preserve, Alaska, USA. Stable isotope ratios of moose and caribou were significantly different from each other in late summer-autumn and winter. Also, late summer-autumn and winter ratios differed significantly between seasons in both species. Nonetheless, we were unable to evaluate whether differences in seasonal isotopic ratios were a result of diet selection or a response to nutrient recycling. We believe that additional studies on plant isotopic ratios as related to ecological factors in conjunction with investigations of diet selection by the herbivores will enhance our understanding of those interactions. Also, controlled studies investigating the relation between diet and physiological responses in herbivores will increase the utility of isotopic analysis in studying foraging ecology of herbivores.

Publication type Article
Publication Subtype Journal Article
Title Utility of stable isotope analysis in studying foraging ecology of herbivores: Examples from moose and caribou
Series title Alces
Volume 37
Issue 2
Year Published 2001
Language English
Publisher Lakehead University
Publisher location Thunder Bay, Ontario
Contributing office(s) Alaska Biological Science Center
Description 13 p.
First page 421
Last page 434
Country United States
State Alaska
Other Geospatial Denali National Park and Preserve
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