Incisor wear and age in Yellowstone bison

David A. Christianson, Peter J.P. Gogan, Kevin M. Podruzny, Edward M. Olexa

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Biologists commonly use tooth eruption and wear patterns or cementum annuli techniques to estimate age of ungulates. However, in some situations the accuracy or sampling procedures of either approach are undesirable. We investigated the progression of several quantitative measures of wear with age, using permanent first incisors from Yellowstone bison (Bison bison), and tested for differences between sexes and herds. We further investigated the relationship of wear and age to explore an age-estimation method. Labial-lingual width (LLW) correlated best with assigned age (r2=0.66, males; r2=0.76 females). Labial-lingual width differed between sexes, with females showing ∼0.2 mm more wear than males. Additionally, differences in rate of wear existed between bison of the northern and central Yellowstone herds (1.2 and 0.9 mm/year, respectively). We developed a regression formula to test the power of LLW as an estimator of Yellowstone bison age. Our method provided estimated ages within 1 year of the assigned age 73% and 82% of the time for female and male bison, respectively.

Original languageEnglish (US)
Pages (from-to)669-676
Number of pages8
JournalWildlife Society Bulletin
Issue number2
StatePublished - 2005


  • Age estimation
  • Annuli
  • Bison bison
  • Cementum
  • Eruption-wear
  • Incisor
  • Yellowstone

ASJC Scopus subject areas

  • Nature and Landscape Conservation


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