Diet alters rodent fecal pellet size: implications for paleoecological and demographic studies using fecal dimensions

Maya Maurer, Karen Peralta Martínez, Brian K. Trevelline, Domenique Tripoli, M. Denise Dearing, Terry Derting, Rodolfo Martinez Mota, Bret Pasch, Kevin D. Kohl

Research output: Contribution to journalArticlepeer-review


Measurements of fecal pellet size can provide important information about wild mammals, such as body size and demographic information. Previous studies have not rigorously tested whether diet can confound these measurements. Furthermore, it is unknown whether diet might alter fecal dimensions directly or through changes in animal physiology. Here, we studied three closely related rodent species that differ in natural feeding strategies. Individuals were fed diets that varied in protein and fiber content for 5 weeks. We then measured body size, fecal widths and lengths, and the radius of the large intestine. Diet composition significantly changed fecal widths in all species. High-fiber content significantly increased fecal widths and would cause overestimations of body size if applied to wild feces. Using path analysis, we found that fiber can increase fecal widths both directly and indirectly through increasing the large intestine radius. Protein affected each species differently, suggesting that protein effects vary by species feeding strategy and existing physiology. Overall, diet and large intestine morphology can alter fecal pellet measurements. Studies using fecal measurements therefore must consider these effects in their conclusions.

Original languageEnglish (US)
Pages (from-to)1619-1626
Number of pages8
JournalJournal of Mammalogy
Issue number6
StatePublished - Dec 1 2021


  • fecal dimensions
  • fiber
  • noninvasive measures
  • paleoecology

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Ecology
  • Animal Science and Zoology
  • Genetics
  • Nature and Landscape Conservation


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