Using Jaw Bones to Age White-tailed Deer

Tooth wear and replacement is one of several methods for aging white-tailed deer.  This technique has ben used for half a century to age and manage deer on ranches across the United States.  Although this method is not perfect, it has been used in the successful management of deer herds.  Deer are aged by examing the wear and replacement of the premolars and the molars of the lower jaw.

As a deer grows older, its teeth continue to wear.  As the enamel begins to wear away, and the exposes the dark dentine material, noticeable distinctions in tooth wear begin to occur between each age class.  Deer are aged in year and half increments, such as 1 1/2, 2 1/2, 3 1/2 etc., since fawns are born from late May through July and are not harvested until the fall hunting season.

Deer managers may be, and should be, interested in deer ages from a deer management standpoint.  Age data provides information about deer herd characteristics, hunting or mortality pressure on a particular age class, and progress of the wildlife management program.

Age data becomes a valuable piece of information when used with other data, such as antler characteristics, dressed body weights, or lactation in females.  As a result of this date collection, deer herd trends can be monitored if enough data is collected over time.  Often these trends can be related to a particular management style, climatic conditions, or any other factors affecting deer.

Field dressed body weights, age, and antler measurements should be collected every year and from every deer harvested to keep a close eye on impact of management activities.

Aging deer using the wear and replacement mehtod is not difficult, but it will require practice on your part.  When aging a deer, it will help to cut the skin along the edge of the jaw t allow better inspection of the teeth.  Of course, if you are planning to mount the deer, you are not going to want to cut the jaw.  Instead, open the mouth and use a flashlight to get a good look.  Otherwise, you can ask the taxidermist to save the lower jaw for you after the skin is caped. 

First, let's talk a bit about tooth terminology.  The basic terms include cusp, back cusp, lingual crest, enamel, dentine, and infundibulum.  A cusp is a point of projection on a tooth.  The back cusp is the very last cusp on tooth 6 on the cheek side of the jaw.  Lingual crest in the tooth ridge adjacent to the tongue.

Enamel is the hard, white, outer coating of the tooth.  Dentine is the soft, dark brown, inner core of a tooth.  And lastly, infundibulum is the crescent shaped depression in the central crown of a tooth between the enamel ridge or crest.

You don't actually need to memorize these terms, but you will definitely need to know what is what when learning how to age deer from jaw bones. 

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Fawn–Aging fawns should not be difficult at all.  For more clarification, inspection of the lower jaw will indicate age.  Fawns have 5 or less teeth present and the third premolar (tooth 3) has 3 cusps.  Tooth 6 has not yet erupted.  In younger fawns, tooth 5 has not erupted and only 4 teeth will be visisble.

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1 1/2–This is an easy one to age.  Tooth 3 has 3 cusps.  Tooth 6 has erupted and is slightly visible just above the gum line.  Also, later in the hunting season you may see tooth 3 as a 2 cusps tooth, but it will just be erupting and will be short.  After 1 1/2 years of age, tooth 3 will always have 2 cusps.

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2 1/2–Lingual crest on all molars are sharp and pointed.  Tooth 3 now has 2 cusps and the back cusp of tooth 6 is sharp and pointed.  Enamel is wider than the dentine in tooth 4, 5, and 6.

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3 1/2–Lingual crest on tooth 4 is blunt.  The dentine is as wide or wider than the enamel in tooth 4.  The back cusp on tooth 6 is forming a concavity.

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4 1/2–Lingual crest on tooth 4 are almost rounded off and lingual crest on tooth 5 are blunt.  The dentine in tooth 4 us twice as wide as the enamel.  The dentine is tooth 5 is wider than the enamel.  The back cusp on tooth 6 is worn so badly that it slopes downward towards the cheek.

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5 1/2–Lingual crest is worn away on tooth 4 and rounded in tooth 5.  Lingual crest in tooth 6 is blunt and dentine in tooth 6 is now wider than the enamel.

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6 1/2–Tooth 4 is worn completely smooth.  No enamel ridge should be visible in the center of tooth 4.  Small enamel ridge will be present in the center of tooth5 and tooth 6.  Lingual crest on tooth 5 is almost worn away and rounded in tooth 6.

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7 1/2–Tooth 4 and tooth 5 are worn smooth.  No enamel ridges are present in the center of these teeth.  Lingual crest is gone from tooth 6.  Infundibulum in tooth 6 is a narrow cresent shape.

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8 1/2–Tooth 4, 5, and 6 are completely dished out and no enamel ridges are showing in the center of these teeth. 

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A simple jaw spreader can be made from 1/4 inch rebar and welded into a simlar shape as the photo below.  Insert the jaw spreader into the mouth as shown.  Make sure the spreader is pushed completely through the mouth and then rotate the jaw spreader downward as shown.  Teeth are now visible for inspection.  A flashlight may be needed on those deer in which you do not want to cut the cheek.