Tests of estimation of age from tooth wear on roe deer of known age: variation within and among populations

The rate of wear of ruminant teeth may vary according to diet, habitat, and individual tooth characteristics. This variation may cause error in estimating the age of wild ungulates from patterns of tooth wear. We tested the ability of 10 observers to accurately estimate age from observation of tooth wear in a large sample of jaws of known-age roe deer (Capreolus capreolus) from three populations. Although the average error was not large (±1.02 years), maximum error ranged from -5 to +6 years for jaws of animals between 1 and 7 years old, with observers generally overestimating the age of young animals and underestimating the age of old animals. We found significant differences among observers in estimation error. When a "jaw-board" of known-age reference specimens was provided, this observer effect was largely controlled for, but accuracy was not improved. Error was partly due to variation in tooth wear, both within and among populations. Initial cusp height of the first molar was lower, but tooth wear te...