FREQUENTLY ASKED QUESTIONS

What are the Different Ways to Age Whitetail Deer?” - by Henry Chidgey
What is Cementum Annuli aging?
Why do people care how old their harvested deer (or other mammal) is?
How does cementum-annuli compare to that of eruption-wear?
How effective are each of the methods for aging Deer? (Cementum Annuli and eruption-wear)
Why do you ask me to provide the estimated age of the trophy? I thought I was sending those teeth to you for you to tell me that!

What is Cementum Annuli aging?

The basis for cementum aging is the cyclic nature of cementum deposits on the roots of mammals’ teeth each year, which results in a pattern of "rings" in the tooth, like those formed in the wood of trees. A darkly staining ring, or "annulus", is formed during winter on most all mammals. Abundant, lightly staining cementum is formed during the growth seasons of spring and summer. Some “experts” say these rings occur because of nutritional or seasonal stress, but since the same rings occur on human teeth, we doubt that is true.

(return to top)

Why do people care how old their harvested deer (or other mammal) is? Mostly asked by our non hunter friends.

The best way we know to answer this is by way of an analogy. If you were a master gardener and your passion was growing tomatoes you might have as an objective raising the largest, most beautiful tomatoes you could. In addition to genetics and nutrition (soil, fertilizer and water) you would want to learn the right time to pick or harvest these tomatoes. You wouldn’t want to pick them too early or too late. Experience of picking too early & too late, over time, would allow you to do a better job at maximizing your goal—having the largest, most beautiful tomatoes you could. Whitetail deer hunters and managers have goals for bucks that are very similar to these master gardeners. They want to have the bucks they harvest achieve their maximum potential. In a whitetail that usually occurs when they are 5-6 years old. They want feedback on the deer that they harvest about how good their judgment was this time, so that they can learn and improve their skills at judging age before they squeeze the trigger or let loose of the arrow.

Another reason for wanting to know the age of harvested mammals is to collect data that enables correlation between habitat and the health of the mammals in that habitat. Body weight vs. age is a great indicator over time of changes in habitat conditions either good or bad.

(return to top)

How does cementum-annuli compare to that of eruption-wear?

The eruption-wear technique of aging ungulates compares the tooth wear of known age animals to the tooth wear of harvested animals. The theory is that you should be able to determine age by finding a match, wear wise, with a known age specimen. I think the cold hard facts show that this is just guesswork, especially for deer 2 ½ years or older. Simply spoken, eruption wear does not work if you want an accurate age of the animal you harvested.

The cementum-annuli (cross-sectioning teeth) method of aging deer, elk and other wild animals is much different. It first requires decalcifying the central lower incisors and then cutting cross-sections of the root tips to a thinness measured in microns. The slice of tooth is then placed on a slide and a special dye is added to enhance viewing. It is placed under a microscope. Circular lines within the tooth’s diameter are readily visible and can be counted much like the rings of growth on a tree, indicating a deer’s age. The question is, how effective are each of these methods for aging deer and other ungulates?

(return to top)

How effective are each of the methods for aging Deer? (Cementum Annuli and Wear/Eruption)

What do Biologists and Their Studies Say About
How to Age Deer and Other Mammals?

In the Journal of Wildlife Management 64(2):441-449 Kenneth Hamlin and 4 other wildlife professionals from the Montana Fish, Wildlife, and Parks concluded (based on a study of 53 known age mule deer and 21 known age whitetail by eruption-wear and 108 known age mule deer and 74 known age whitetail by cementum annuli) “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…. Ages assigned by eruption–wear criteria were not reliable for comparing physical measurements and population parameters by age among populations…. Accuracy for a sample of known-age mandibles aged by eruption-wear criteria was 62.3% for mule deer, 42.9% for whitetails, and 36% for elk”. “The accuracy for individual biologists ranged from 54.7-71.7% for mule deer and 23.8-66.7% for whitetail deer” “This aging was done by 4 biologists from Montana and 2 from Washington considered to be experienced in aging deer used eruption-wear to age these mandibles…”. Cementum annuli aging yielded a 92.6% accuracy rate for mule deer (with no error over 1 year), 85.1% accuracy rate for whitetails (only 2 in error over 1 year) and 97.3% accuracy rate for elk.

Ken Gee, a wildlife biologist at the 2,947 acre Noble Foundation Wildlife Unit (NFWU) said at the conclusion of a study he did in 1996 “These results indicate that this widely used technique (sic eruption-wear) is very inaccurate for classifying adult deer into specific year age-classes on the NFWU….(it)only allows us to confidently place deer into three age classes: fawn, yearling, and adult.” The study was done using “34 practicing, established, well respected deer biologists from the southeastern U.S. that commonly use the technique (sic eruption-wear).”

(return to top)

Why do you ask me to provide the estimated age of the trophy? I thought I was sending those teeth to you for you to tell me that!

We are compiling statistics on the variance between what experienced hunters estimate as age vs. actual age. As we have enough data to be statistically significant, we will post that data here.

(return to top)