In a study done by Kenneth L. Hamlin et al. of the Montana Fish, Wildlife, and Parks ( Journal of Wildlife Management 64(2):441-449) accuracy rates of cementum annuli were 97.3% for elk through age 14, 92.6% for mule deer through age 14, and 85.1% for white-tailed deer through 9 years old.
Tooth eruption or tooth replacement is a highly reliable way to age mammals until they have all their permanent teeth. In whitetails you can accurately place deer as 6 months old, 18 months old, or 2 ½ or older using this easily learned technique.
This is probably a good time to bring up one of the most popular and prevalent myths of how to age game mammals, molar wear aging. This technique suggests that we should be able to determine the age of a mammal by looking at the wear on the molars. Sort of like determining the age of your tires by tread wear. In the same study by Hamlin referred to above; the accuracy of molar wear aging was 62.3% for mule deer, 42.9% for whitetails, and 50% for elk in the 3-4 year classes, 16% for elk 5 years old. They ultimately concluded that “The accuracy provided by the cementum annuli method is necessary to determine whether various physical and population parameters change significantly with age of the animal.” So what is the source of this popular myth of molar wear aging? In 1949 Wildlife Biologist C.W. Severinghaus published a study “Tooth Development and Wear as a Criteria of Age in White-tailed Deer” Journal of Wildlife Management 13:195-215. In this study he suggested two methods of aging; Eruption or tooth replacement aging and Molar wear aging. Subsequent studies since 1949 have supported his eruption aging results, but no study has been able to validate his hypothesis concerning molar wear aging. In fact in addition to the Hamlin study cited above here are some more comments by wildlife biologists in recent years:
….this widely used technique (molar wear) is very inaccurate for classifying adult deer…. (Ken Gee, Wildlife Biologist, Noble Foundation Wildlife Unit 1996 study)
We believe age-specific information and conclusions drawn….using the tooth-wear aging technique to “determine” ages of adult white-tail deer are unfounded…Review of all other published data sets using known-age deer supports this conclusion.(Wildlife Society Bulletin 2002, 30(2):387-393 Ken Gee et al.)
Ages assigned by … wear criteria were not reliable….. (Kenneth Hamlin et al. 2000 Journal of Wildlife Management 64(2):441-449)
….we conclude that tooth replacement and wear should be used for deer <2-1/2 years old, while cementum annuli should be used for deer >3-1/2 years old. (Mickey W. Hellickson, Ph.D. King Ranch Chief Wildlife Biologist 2007)
Curiously this molar wear aging is still part of the course curriculum taught to current wildlife biology students. That is probably a key reason that the myth continues.
In conclusion, if someone wants to really know the age of mature trophy game mammals, the only choice is cementum annu