Aging deer on the hoof is not an exact science by any means, and those who claim to identify the exact age of a 5.5 year-old buck cannot really be certain (blowing smoke?) unless they have, in fact, observed individual deer for a number of years. However, well-trained and experienced individuals can usually tell whether or not a buck falls into one of five age categories. The age ranges and descriptions as I have learned them are as follows:
1.5 Easiest to identify. Almost always a smaller, sleeker buck with thin antler bases of less than 2.5 inches in diameter. Body size is equal to or less than many does in the herd. Narrow face and slim neck. Calm movement is quite energetic and very limber. Behavior more like does than any other age of bucks.
2.5 This buck has begun to outgrow the does. Body width and overall size is as good or better than most of the herd does. Antler bases are thicker (2.5 - 3.5 inches) than the yearling buck, but not yet of trophy proportion. Antler mass is still lacking trophy proportion also. Deer still has a sleek and long appearance, but is wider and more muscular than the yearling. The face is fuller and in rut the neck takes on the characteristic swell, although usually moderate. Calm movement is spry and quick, with ample energy.
3.5 to 4.5 These bucks are much larger and wider than does, usually have thick antler bases of 3.5+ inches, and antlers are reaching trophy proportions on genetically superior animals. Legs, neck, body, and face are thick and strong. Whole ody takes on a deeper and more blocky contour. Wrinkles are apparent in the upper folds of the ears. Belly line begins to take on the slight swell or dip of "middle aged gut". Movement is forceful and strong, but lacks some of the wasteful energy of younger bucks.
5.5 to 7.5 These bucks have taken on the so called "pot gut" appearance, where the belly line begins to sag in comparison with younger deer. Antlers are thick from base through the end of main beams, with maximum mass and dimensions. Genetically superior animals will have trophy antlers. Face remains full and often develops distinct "brow line" between stiff, lighter, upright hair on the crown of the head and sleeker, darker flattened hair on the muzzle. Fold in upper ears are multiple and noticeable. Ears often lack thick hair on the inside, and can have multiple scars or nips. Body is bull-like: thick, wide, and powerful, with large swollen neck up into the head line during the rut. Mature bucks are cautious, cagey, and almost always dominant in the whole herd. Calm movement is strong and determined, but very deliberate and usually conservative of energy (straight line of movement over shortest path).
8.5 + These deer are large, although the power and finesse of the prime years has passed. Belly line has a distinctive sag, and hair often takes on a hoary "grey" appearance. Antlers have thick bases, but are often not well-developed or are deformed in some way. Face develops contours, body contour appears somewhat segmented, rather than sleek and continuous. Upper ears have definite and numerous wrinkles, ear hair is often well-thinned. Frame and bones are massive, but muscles and rut neck swell do not quite match this proportion. Calm movement has a noticeable stiffness and slowness. Old bucks often do not show dominance in the buck pecking order, even though they are larger than other bucks.
