Photosynthetic pigments estimate diet quality in forage and feces of elk (Cervus elaphus)

D. Christianson, S. Creel

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Understanding the nutritional dynamics of herbivores living in highly seasonal landscapes remains a central challenge in foraging ecology with few tools available for describing variation in selection for dormant versus growing vegetation. Here, we tested whether the concentrations of photosynthetic pigments (chlorophylls and carotenoids) in forage and feces of elk (Cervus elaphus L., 1785) were correlated with other commonly used indices of forage quality (digestibility, energy content, neutral detergent fiber (NDF), and nitrogen content) and diet quality (fecal nitrogen, fecal NDF, and botanical composition of the diet). Photosynthetic pigment concentrations were strongly correlated with nitrogen content, gross energy, digestibility, and NDF of elk forages, particularly in spring. Winter and spring variation in fecal pigments and fecal nitrogen was explained with nearly identical linear models estimating the effects of season, sex, and day-of-spring, although models of fecal pigments were consistently a better fit (r2 adjusted = 0.379–0.904) and estimated effect sizes more precisely than models of fecal nitrogen (r2 adjusted = 0.247–0.773). A positive correlation with forage digestibility, nutrient concentration, and (or) botanical composition of the diet implies fecal photosynthetic pigments may be a sensitive and informative descriptor of diet selection in free-ranging herbivores.

Original languageEnglish (US)
Pages (from-to)51-59
Number of pages9
JournalCanadian Journal of Zoology
Issue number1
StatePublished - Nov 26 2014


  • Carotenoid
  • Chlorophyll
  • Diet selection
  • Digestibility
  • Energy
  • Foraging behavior
  • Nitrogen
  • Phenology
  • Photosynthesis
  • Primary productivity

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Animal Science and Zoology


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