What killed this White-tailed Deer? Part 2: Sex Determination and Tooth Wear Pattern

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DUE TO THE GRAPHIC NATURE OF IMAGES PRESENTED 

WITH THE PRIMARY INTENTION OF 

BIOLOGICAL RESEARCH AND ENVIRONMENTAL EDUCATION

I wanted to determine the sex and age of the animal, first.  It was a female because I observe nipples that lacked hair where she nursed her young previously this year.  I also did not observe pedicels, which is where antlers would be attached to the frontal bone on the skull of males.  The best way to age white-tailed deer is to examine the teeth's wear pattern.  I needed to cut the cheek of the animal so that I could expose the teeth better (Figure 1).

Figure 1:  White-tailed deer cheek cut to expose teeth
for better inspection of tooth wear, notice eye was removed by scavenger.
Photo By James Fischer

Examining the tooth wear patterns looks complicated at first but it gets easier with practice.  We are examining the patterns of tooth loss and eruption/replacement for the first 2 years of their life.  Animals older than 2 years old have permanent teeth which wear down as the animal chews the vegetation it eats everyday.

Figure 2:  White-tailed deer mouth showing
the animal's upper and lower right mandible's cheek teeth,
as well as the tongue and the lining inside the cheek .
Photo By James Fischer

We examine the pattern of enamel and dentine (dentyne) wear patterns to accurately age white-tailed deer (Figure 2).  Deer teeth have exposed dentine which is softer than enamel but denser than skeletal bone.  Human teeth are composed of dentine but it is surrounded by hard enamel.  The layering of dentine and enamel create a surface with different friction gradients which is very effective for masticating (chewing) vegetation and exposing the vegetative cells to flora that is found in their gut, which occurs when the animal regurgitates and chews it cud.   Although this is an effective strategy for chewing vegetation, it also allows the teeth to wear down.  The habitat that the animal lives in can change the wear pattern slightly.  For example, animals that live in an area with sandy soils will have teeth with a slightly different wear pattern than animals that inhabit a area of loam soils.  The sand will occasionally be chewed because it is on the plants that the animal eats.  Although there are overall patterns that remain consistent across all white-tailed deer populations, some interpretation is needed when judging the age by tooth wear.  It takes lots of practice, but it can be fun.  The best way to learn this pattern is by practicing with jaws of differently aged animals (new born fawns to 10+ yrs old).  

Tune in tomorrow to learn the age of this animal and what characters I used to distinguish it's age!  

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What killed this White-tailed Deer? Part 3: Age Determination by Tooth Wear Pattern

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Advisory:  Please do not touch, feed, or disturb wild animals of unknown origin.  If you see an animal in distress please contact a licensed animal control officer, licensed wildlife rehabilitator, or other trained and certified wildlife professional.  You may expose yourself or the animal to unnecessary injury, distress, or disease.  This procedure was performed by a professional wildlife biologist who took proper precautions to avoid exposure to pathogens and other potential human-wildlife diseases.