Variability in Aging Maine White-Tailed Deer by Tooth-Wear Characteristics

Abstract

A sample of 682 incisor teeth collected from Maine deer (Odocoileus virginianus) during the 1968 hunting season was histologically prepared and the cemental annuli counted. The ages determined by this technique were compared to ages assigned under field conditions by ten biologists using the toothwear method. More deer were assigned to the younger age-classes ( 1/2 years) by tooth-wear characteristics than by annuli counts. The percent difference between deer assigned to each age-class by the two methods increased from 6.3 percent for yearlings to 100 percent for deer 61/2 years of age or older. Individual biologists placed an average of four deer of every ten examined into a different age-class than that determined by annuli counts. The validity of determining the age of white-tailed deer by tooth-wear (Severinghaus 1949) has been questioned. Differences in the wear characteristics of deer teeth prompted at least one management agency to revise the criteria used locally (Ryel et al. 1961). Furthermore, variation in individual interpretation of wear, especially under field conditions, led to further aging discrepancies (Ryel et al. 1961, Gilbert 1964). With the adaptation of a more precise aging technique, cemental annuli analysis, to North American deer, (Low and Cowan 1963; Gilbert 1966, Ransom 1966), it became possible to determine the inherent variations in the tooth-wear method. While certain studies (Ludwig 1967, Campbell 1967) have shown the greater precision of the annuli-counting technique, there have been apparently to date, no direct comparisons under normal data collection procedures by a game agency during the deer season. The purpose of this study was to ascertain the differences between ages assigned to Maine deer in the field by the tooth-wear method and in the laboratory for the same deer by cemental annuli counts. 1 A contribution of the Federal Aid in Wildlife Restoration Act, Maine Project W-37-R. 532 The cooperation and assistance of the biological staff of the Maine Inland Fish and Game Department's Game Division were sincerely appreciated.