A Guide to Age Determination of White-tailed Deer

1. What they did

This short illustrated booklet from Texas Parks and Wildlife explains how to tell the age of a white-tailed deer from the wear and replacement of the cheek teeth in the lower jaw. Texas Parks and Wildlife biologists had used this method to manage deer on ranches, wildlife management areas and by county since 1965. The authors say the method is not perfect but has served deer management in Texas for over 35 years.

The booklet names the parts of a deer tooth (cusp, back cusp, lingual crest, enamel, dentine and infundibulum), numbers the cheek teeth 1 to 6 from front to back, and then shows a labelled photograph of the jaw for each age class, from fawn to 8 1/2 years. The back cover shows how to make and use a simple jaw spreader.

2. What they found

Why ages come in half years

Fawns are born from late May through July and are not harvested until the autumn hunting season, so deer are aged as 1 1/2, 2 1/2, 3 1/2 years and so on. As a deer grows older, the white enamel wears away and exposes the dark brown dentine underneath, giving visible differences between age classes.

The age classes

• Fawn (1/2 year): 5 or fewer teeth; tooth 3 (third premolar) has 3 cusps; tooth 6 has not erupted. Younger fawns show only 4 teeth.
• 1 1/2 years: tooth 3 still has 3 cusps; tooth 6 has erupted and is just visible above the gum line.
• 2 1/2 years: tooth 3 now has 2 cusps (the permanent tooth); lingual crests on all molars are sharp and pointed; the back cusp of tooth 6 is sharp; enamel is wider than dentine in teeth 4, 5 and 6.
• 3 1/2 years: the lingual crest on tooth 4 is blunt; dentine in tooth 4 is as wide as or wider than the enamel; the back cusp of tooth 6 is forming a hollow.
• 4 1/2 years: lingual crests on tooth 4 almost rounded off and on tooth 5 blunt; dentine in tooth 4 twice as wide as the enamel, and wider than the enamel in tooth 5; the back cusp of tooth 6 slopes down towards the cheek.
• 5 1/2 years: lingual crest worn away on tooth 4, rounded on tooth 5 and blunt on tooth 6; dentine in tooth 6 now wider than the enamel.
• 6 1/2 years: tooth 4 worn completely smooth, with no enamel ridge in the centre; small enamel ridges remain in the centre of teeth 5 and 6; lingual crest on tooth 5 almost worn away and rounded on tooth 6.
• 7 1/2 years: teeth 4 and 5 worn smooth with no central enamel ridges; lingual crest gone from tooth 6; the infundibulum of tooth 6 is a narrow crescent.
• 8 1/2 years: teeth 4, 5 and 6 completely “dished out”, with no enamel ridges showing.

Practical tips

• Aging this way is not difficult but takes practice.
• Cutting the skin along the edge of the jaw gives a better view, but not if the deer is to be mounted; taxidermists will save the lower jaw if asked.
• A jaw spreader (which can be made from 1/4 inch rebar) and a small flashlight help when the skin is not cut.
• Clean away food and debris, and check the teeth on both sides of the jaw to make sure the wear is consistent.

3. What they concluded

• Age data tell managers about the make-up of a deer herd, hunting or other mortality pressure on particular age classes, and how a management programme is progressing.
• Age is most valuable alongside other data such as antler measurements, dressed body weights and lactation in females. Collected over time, these data show herd trends that can often be linked to management, climate or other factors.
• The authors recommend collecting dressed weight, age and antler data every year from every deer harvested, because partial or occasional data may lead to uninformed management decisions.

6. Other technologies, skills or innovations

• A simple home-made jaw spreader of 1/4 inch rebar, pushed right through the mouth and rotated downward to hold the jaw open, plus a small light for viewing the teeth.

7. Implications for conservation (from the paper)

• Regular aging of harvested deer, combined with weight and antler data, lets landowners and managers monitor deer herds and judge whether their management is working.