Comparison of Novel Invasive and Non-invasive Age Determination Methods to an Existing Age Determination Method in White-talied Deer

Abstract

The tooth eruption and wear method of age determination was performed on a sample of 96 white-tailed deer (Odocoileus virginianus) harvested from a population in northern Michigan. Following initial aging, two potential methods of age determination in white-tailed deer, one invasive and one non-invasive, were analyzed to determine whether age-related changes exist. Eyes were fixed in formalin (invasive) and lenses were removed and weighed. Ear cartilage (non-invasive) was digested and inductively-coupled plasma spectroscopy was performed to test for sulfur and calcium content. Logarithmically-transformed multiple regression analysis and curvilinear regression analysis were performed to determine relationships between these untested methods and the tooth eruption and wear method. Following multiple regression analysis, only log eye lens mass and log S/Ca ratio significantly explained log tooth age (p < 0.001). The contribution of explained variance by log S/Ca ratio was minimal, therefore further analysis was performed using curvilinear regression analysis. The power model of curvilinear regression analysis determined that eye lens mass explained variance in age class 61.5 percent of the time (p < 0.001).