We investigated the precision and accuracy of age estimation by cementum annuli counts for Maine black bears (Ursus americanus). Precision of age estimation was assessed by: 1) a repeated measures analysis of variance design to evaluate effects of reader, reader experience, bear sex, bear age class, and trial; and 2) pair-wise comparisons of estimated years of birth (YOB) from series of premolars removed from bears over periods ranging from 2 days to 12 years. Age estimation accuracy was assessed through pair-wise comparisons of cementum-assigned YOB to known YOB for known-age bears. Experienced readers assigned significantly (P = 0.0001) lower age estimates than inexperienced readers; greater differences in age estimates occurred in old bears. Least variation in age estimates occurred in experienced readers' estimates for young bears (SD = 1.08 yr). Experienced readers estimated age more precisely over 3 trials than inexperienced readers (P = 0.0051). YOB estimates from multiple teeth removed from individual bears showed decreasing agreement with increasing time between tooth removal (P = 0.002), and decreasing agreement with increasing age of bears (P < 0.001). Teeth removed later in life yielded later YOB estimates than teeth removed earlier. Cementum age estimates are accurate for bears ≤6 years of age, but may underestimate age in older bears. Managers using cementum age estimation should recognize the technique's limitations in precision and accuracy, and minimize changes in personnel and methodology to reduce variation in estimates over time.
- Volume 8
- Issue
- Pages 415-419
- Publication Date 1 January 1990
- DOI 10.2307/3872945
- File Size 232.32 KB
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