Among the most important things in managing deer on your property is the ability to determine the age of harvested deer, keeping records of that data, and using it to get the results you seek. Most of the other information you might collect, such as weight and antler growth, as well as resulting management strategies you might employ, have little meaning without knowing the age of the deer.
The age of white-tailed deer is estimated by examining tooth replacement and wear patterns in the lower jaw. While it is not an exact science, especially when aging older deer, anyone with knowledge and some experience can accurately age deer.
Normally the jaw bone is removed for closer examination and to keep it for later reference.
How old is that deer? It is interesting and useful to know.
Teeth can be aged and recorded at harvest, but generally greater accuracy and consistency will be achieved if the ages are assigned after the season once all jaw bones have been collected and can be compared.
Jaw Bone Removal And Handling
Note that when we are talking about a jaw bone, we are talking about one side of the lower jaw. There are various methods for removing a deer’s jaw bone, some more refined than others. A professional approach promoted by the South Carolina Department of Natural Resources — one that will leave the cape undamaged for those wanting a head mount — involves a long-handled pruning shears and special jaw tool. The tool is made from a 46-inch piece of steel bar and is used to open the mouth, free the jaw bone, and help extract it.
After removal, clean the jaw bone and mark it immediately for identification (most deer managers simply write on it with a black permanent marker). Keep it in a place it can dry out and be safe from scavengers.
Types And Nature of Deer Teeth
Deer have three types of teeth. Those at the front are called incisors. They are used for biting and collecting food. The next set of teeth, several inches back of the incisors, are called premolars. They are immediately followed by larger teeth called molars. Premolars and molars are primarily for crushing and chewing food. A mature deer has three each per side.
As with most animals, the back teeth of a deer are made up of a dense, dark substance called dentin that is covered by harder, whiter, shinier material called enamel. With deer, the enamel covering isn’t complete and some of the darker dentin shows through. Comparing the visibility of dentin to enamel is one way of determining deer age.
The first and easier step in estimating a deer’s age is to determine if the harvested deer is a fawn (six months old), yearling ( 1-1/2 years old) or a mature deer (2-1/2 years or older.) This is done by examining the number and nature of the teeth. Tooth growth and replacement is very predictable according to a deer’s age.
If the jaw bone has five or fewer teeth, that means the deer has not grown all its molars yet and the deer is a fawn. If the deer has all its teeth (six) it is a yearling or older. You can separate the yearlings from the mature deer by examining the third premolar. A yearling will still have its “baby teeth,” or a third premolar with three cusps — in effect a three-part tooth called tricuspid — or it may be in the process of being replaced with the new adult tooth, which has two cusps (bicuspid). This permanent tooth erupts predictably at 18 months and is fully in place a month later. If this tooth shows some wear and staining, the deer is mature — 2-1/2 years or older.
Determining the age of a mature deer is trickier, and depends on judgments based on tooth wear, staining, and other evidence. The older a deer gets, the more dull, worn, and dark its teeth become. You will be examining how the darker dentine compares to the enamel and wear on the sharp ridge of crests running along the inside (tongue side) of the jaw, called the lingual crest. Here’s what you should find according to deer ages.
19 Months-Plus: Third premolar will show little or no darker dentine line. Little tooth wear evident.
2-1/2 Years: Third premolar now shows dentine line. Tooth wear will be evident, but not considerable. Molars will be sharp and have enamel showing well above the height of dentine. Amount of dentine visible compared to enamel will be about equal on the first molar, narrower on the other molars.
3-1/2 Years: Wear is now more noticeable especially along the crest. All premolars show wear — the second cusp of the third premolar will have a worn, cupped appearance. Dentine is now more visible than enamel on first molar, equal on the second, smaller on the third. The last cusp of the back molar is flattened.
4-1/2 Years: Considerable tooth wear evident. Crest on the first molar is gone or nearly gone. Dentine may be twice as apparent as enamel on the first molar, wider on the second, and about equal on the last.
5-1/2 Years-Plus: Considerably more dentine compared to enamel is evident on all molars. Severe and progressive tooth wear is evident. As deer approach the end of their life expectancy (about 9-1/2 years max) teeth may become worn down to the gum line.
Accurately aging deer can be difficult until you gain experience. Information, resources and tools to help you age deer are available on many websites including the Dane County Conservation League.
Using Age Data For Deer Management
Keep a log with entries corresponding to your numbered jaw bones. Record deer weights, antler scores, physical descriptions, dates and locations of harvest, and other data. It will take awhile for patterns to develop and needs to become apparent. One of the first will be an indication of the age of bucks according to antler size and other physical characteristics. This is also one of the most important results of deer aging — helping hunters learn so they don’t shoot bucks before they are mature.
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