Field Aging Whitetail Deer
Using Body Structure Indicators

 

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Why Bother to Field Age Deer?
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By being able to field judge the age of bucks more accurately, we can better manage our deer herds. We can maintain age class diversification, and better choose which young bucks to eliminate and which ones to keep for genetic improvement of antler characteristics in the future.
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Significant amounts of research indicate that a buck deer will usually not grow it's best rack until after it's body has fully developed. Until then, most of the nutritional intake is expended toward making bones and muscle. The full body development is normally complete about age 5 in whitetail. That means, the best rack a deer can grow will usually occur at age 5, 6, 7 or 8. Exactly which one set of antlers becomes the best depends on habitat, weather, amount and quality of supplemental feeding, also any injury and/or sickness to which the buck is subjected. About age 8, and sometimes earlier in very sandy country, the buck's teeth are worn down to where it is difficult to grind his food enough to release the nutrients. Antler size and body condition frequently declines after this. The deer simply can't eat enough to sustain himself.
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Based on this research, it only makes sense to pass up young bucks with large racks, since they have a very good chance of becoming even bigger in the near future. That also gives them a chance to pass on those genes for a large rack for another year or two. Conversely, the research also lets us know that a buck of 6 to 8 years has almost no chance of getting a bigger rack, and may actually soon be getting smaller, so he might as well be taken, regardless of rack size.
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SO, HOW DO WE FIELD JUDGE AGE?
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In General
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No single factor can be used to conclusively judge the age of a deer in the field. The picture at right illustrates the main indicators that should be evaluated overall to get a good estimate for a buck. The individual indicators will often vary a little from one region of Texas to the next, and sometimes even within an individual herd. If you can view known age bucks (ear tagged as fawns) in the area, you can quickly get a better read on your local herd's distinguishing characteristics.
Using the Rack as Indication of Age
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Notice that the rack (antlers) is not depicted above as an indicator. While some very general statements can be made about antler developmental characteristics at certain ages of  a buck, the rack is the least reliable of any indicator. Remembering that these statements have MANY EXCEPTIONS, antlers generally gain mass as the buck ages, generally get darker as the buck ages, generally get wider as the buck ages, and will get any nontypical points in it's genetics once the buck has matured body wise. So, if a buck's antlers are wider than it's ears, dark in color, seem thick in the beam circumferences, and have some nontypical points,  chances are good that the buck is mature. Because of the tooth wear, a post mature buck's rack may actually start getting smaller from year to year, but they usually keep the basal circumference, then it will thin out quickly from there.
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FAWN
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Many people think they could never mistake a buck fawn for a doe, but every year we have too many of those same folks wind up doing just that. On the head, the pedicels (nubs) are the most obvious clue. The ears will appear long, and the nose will appear short. The body will be smaller than the adult doe's, but is bigger than a doe fawn, so be careful. The legs look long and skinny, and the gait is usually frisky, often frolicking. The tarsal glands will be small and snow white. Does seldom travel alone, so give it a few minutes to see if more deer show up for comparison. I've seen many buck fawns by themselves.
1 AND 1/2 YEARS
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At this age, a buck looks like a doe with antlers. There will usually be a slight dip in the back. They have a thin neck, no defined brisket, white tarsal glands, and the belly line has a distinct up turn near the hams. This gives it a greyhound racing dog sort of look. The legs still look very long, and the gait is still pretty frisky. They will make unwanted sexual advances on does, but are very timid in the presence of older bucks. 
2 AND 1/2 YEARS
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At two and a half, the animal starts bulking up a tad, but just a tad. The neck will be bigger than a doe or yearling buck, but not much. The legs still look fairly long. The face looks long and the skin tight. Eyes are near perfectly round. Slightly developed brisket. The belly still has somewhat of an upturn near the hams. The tarsal gland may have some color to it. The rump appears squared off.
3 AND 1/2 YEARS
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A three and a half year old buck reminds me of a racehorse. They are usually very lean muscle, and act ready for action. They may make rubs and scrapes if no bigger bucks are present. The neck continues to get bigger, making the head look shorter. The nose broadens, adding to this illusion. The brisket is noticeable but not pronounced. Legs look the right length now. The belly line is flat, with little up turn at the rear. The tarsal gland will be dark in rut. Rump starts looking more rounded at times and squared off at times, depending on stance. Back line is flat.
4 AND 1/2 YEARS
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If fed well, a 4 and a half year old buck really starts looking like a buck. The giveaways now are the back and belly lines, and the head. On level ground, the back will have a slight dip only, and the belly will not hang below the chest line. The head skin will not look tight or loose, and the eyes almost round but not quite. When one of these bucks walk, they still pick their feet up pretty good, and the front knees won't look bent in when the deer is walking toward you. Rump is getting pretty round, and tarsal glands will be black when near or in rut. Nontypical points may start to show up now.
5 AND 1/2 YEARS
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This one gets hard to pass up. Unless your herd is well managed, most bucks don't make it to this old, but you should actually let a buck get at least 6 before you hammer them to achieve maximum antler potential. Now, the eye will not be round anymore, it starts to look squinty. The brisket is obvious where it joins the neck. The belly hangs even with the chest or starts to hang below it a bit. They start walking knock kneed somewhat. They seem more deliberate in their actions. Skin on head starts looking a bit loose. Often have  nontypical points.
6 AND 1/2 YEARS
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When a six year old walks out, it's usually pretty obvious. All other deer pay attention. He is on top of his game and knows it. Actions are very deliberate, like a big bull swaggering in. The front knees bend in to handle the weight of the neck and rack. The belly and back sags from years of fighting gravity. When relaxed, the ears tend to droop down a bit for the same reason. The rump is well rounded. The brisket obvious. Eyes are squinted; almost mean looking. With good nutrition, all nontypical points in his genes will pop out now. This is what you've waited for. TAKE HIM!
PAST 6 AND 1/2 YEARS
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When a buck's teeth wear out, somewhere between 7 and 9 years old in normal habitat, antler and body conditions deteriorate. It is actually fairly easy to mistake a 9 year old deer for a  3 or 4 year old deer. The giveaway indicators though are the head, neck and rump. Also, muscle tone. The head will continue to have the loose skin, and the eyes will still be squinty, as in other mature bucks. The rump, however, will lose mass, not appearing rounded anymore. It won't be smoothly squared off like a young buck, either. It will be bony looking. The back may also be bony looking. Even the shoulders won't look so well muscled, and the neck certainly won't. I've noticed also that just like old men tend to get gray hair, an old buck tends to look lighter in color than other deer in the area. Not gray so much, but more of a lighter brown. Often, the hair also appears course.
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