Comparison of Two Age-Estimation Techniques for Cougars

Abstract

Age estimation in wildlife is crucial for population assessment and management decision-making. Estimation errors may reduce the efficacy of management programs or potentially result in poor management decisions. Our objective was to compare aging techniques (gum-line measurement and cementum annuli analysis) for Cougars (Puma concolor) using harvest data collected during 2006–2010 in Oregon. Differences in paired age estimates (cementum annuli estimate minus gum-line recession estimate) had 95% confidence limits of −0.28 and −0.06. Linear regression showed a relatively high level of agreement (<1.0-y difference) between the 2 aging techniques considered for individuals ≥1-y and ≤17-y old. The slope suggests that each 1 y increase in estimated age using cementum annuli analysis adds 1.03 y to the predicted estimated age using gum-line measurements. Disparity between estimates increases with age. Individuals estimated to be 1-y old using x (cementum annuli counts) are predicted to be 1.09-y old using y (gum-line measurements), and individuals estimated to be 12-y old using x are predicted to be 12.42-y old using y. The use of >1 age-estimation technique, implementation of standardized protocols (if not currently in place), and additional training to potentially increase consistency and reduce bias among observers will be beneficial for Cougar management.