PITTSBURGH (TNS) — The rut is approaching fast. At the height of mating season, whitetail deer will be hormonally addled, acting strangely and oblivious to even the most extreme dangers.

Knowing a deer’s age can explain some of its actions and help to predict future behaviors. Wildlife watchers can estimate the age of familiar backyard browsers using the long-established observational tools relied upon by hunters.

“Aging” a deer on the hoof can be an important part of the hunt. Establishing personal harvest parameters before leaving home is routine among many experienced hunters. It’s a conservation thing. Deciding to pass on deer that haven’t reached reproductive age means allowing a 1 1/2-year-old buck to grow into a healthy 3 1/2-year-old, 8-point that has left its mark on the gene pool. Or it could mean choosing to cull an aging doe that will no longer reproduce but is consuming valuable nutrition in sparse woodlands.

The buck outside your window cannot be accurately aged by counting points. Production of antlers has more to do with nutrition than age or genetics.

Antlers are not horns, which are permanently attached to the skulls of cattle. Antlers develop from the fastest-growing tissue known to science — densely packed blood vessels that advance as much as 1 inch per day in the spring. The vessels close, die and harden. Dead tissue on the outside of antlers, “velvet,” is scraped off. The buck usually continues scraping or polishing his hardened antlers, using them in head-to-head battles for breeding rights. Antlers are generally shed after the rut in late winter.

In old bucks or in deep woods and other places where browse is minimal, less nourishment reaches the tissue, impeding growth and creating smaller antlers with fewer points. In robust, fertile, year-round deer smorgasbords like suburban housing plans, high-quality nourishment results in advanced antler growth.

Physical cues are more useful in gauging a deer’s age. Biologists with access to tranquilized deer examine wear of the premolars and molars of the lower jaw. As deer grow older enamel wears off the teeth, and the age can be more accurately determined by differences in the amount of wear.

Hunters and wildlife watchers can’t examine teeth. But they can estimate the age of antlered and antlerless deer by considering the shape and proportionality of body parts live or through webcam images. Here are some signs to look for:

5 months-1 1/2 years

By autumn, most of the current year’s fawns have lost their spots, but they’re still very small — larger than a big dog but clearly thin, still slightly awkward and never more than a few leaps away from their mother. On average, does each drop 1 1/2 fawns per year. Twins are common when food is ample, and triplets can be born in browse-filled suburbs. Behavior also offers hints to an animal’s age. Spindly-legged deer with no visible antlers playing when they should be eating near a watchful doe were probably born in the current year.

At 1 1/2 , they are still smaller than mom. Yearlings have skinny necks, disproportionately long legs and thin, lean bodies with hind quarters that are larger than the front end. Males will have spikes or forked antlers.

Image DescriptionThis 2 1/2 -year-old buck has a thin neck, small shoulders and a back end that seems bigger than his front end. (Wikipedia)

2 1/2 years

A buck could have a six- to eight-point rack, a fit body and be sexually active during the rut. On closer examination, however, the antlers will seldom be wider than the ears and may appear on the thin side. Despite a muscular build, the necks of males and females remain thinner than the brisket. The belly is flat, but the back end still appears bigger than the front end.

3 1/2 years

Full antlers for bucks and in both sexes, a thick, full neck that appears to stop at a big, broad chest. Look for a firm, flat belly and no dip or sway of the back. In the third year, the front finally seems larger and more developed than the hind quarters. Adult deer have learned a thing or two. Behaviorally they’re more cautious, creeping through grape thickets, hesitating, cocking their heads with ears up and alert. In the rut, however, they still could spring out of the brush and run headlong into a tractor-trailer.

4 1/2 years

A buck of this age has developed about 90% of his antler potential, although that depends on habitat availability. Beneath the head, the necks of fully mature bucks and does are large and full from the chin to the barrel chest as it curves into the belly. There’s a bit of paunch to that belly and the middle of the back seems to droop a bit from carrying all that weight.

5 1/2 years and older

In their fifth year, males and females look sort of top heavy with disproportionately shorter legs. A thick neck meets front shoulders covered with a muscular hump. Below a swayed back hangs a sagging belly.

Bucks of this age may have spectacular racks, but on the far side of 5 1/2 years teeth may become too worn to efficiently browse. Disease may also contribute to less intake of nutrition and less robust antlers. The only time antler shape directly correlates to age is when thin, spindly spikes emerge from the head of a big, full-bodied buck. Don’t say old, he’s just past his prime.