Antlers: What makes them so big?

30_cooperFIRST DEER  — Cooper Dailey, 12 years old, completed a Hunter Safety course and while hunting with his grandfather Dick Dailey, west of Dupuyer near Swift Dam, brought down his first deer, a nice 5x5 mulie. He used a Savage .270 rifle and one shot from 100 yards. An uncle, Bob Dailey and a cousin, Bo Dailey were part of the hunting party.  For the I-O courtesy of the Cooper family

By Bruce Auchly, Region 4 PIO

It’s that time of year when hunting talk centers around antlers or “horns.”

It happens throughout the fall, but in spades during Montana’s five-week deer and elk general season. Probably because there are so many people afield now: about 240,000 gun hunters versus maybe 40,000 archers back in September at the peak of archery season.

Also, everyone, it seems, wants a trophy rack to hang on the wall at sometime in his, or her, life. Even many meat hunters profess a desire for one big bull elk or buck deer before they head to the happy hunting grounds in the sky.

Maybe that yearning explains why there are misperceptions about what it takes to grow antlers and why not every deer and elk that reaches maturity will sport massive headgear.

First, deer and elk grow antlers, not horns. Most hunters know the difference, know that antlers only grow on male members of the deer family, that they fall off each year and grow back. Most hunters know that horns are permanent and found on mountain goats, bighorn sheep and bison.

Sure there are exceptions: male and female caribou, which are in the deer family, have antlers. Antelope have horns but they shed the outer covering or sheath each year. But as long as everyone is straight on the important differences, it’s okay to use the colloquial term, “horns.”

Second, genetics and nutrition play major roles in horn growth. Generally, genetics determine the form of antlers while nutrition dictates their size.

Inheritance seems easy enough to understand. A mature bull elk with seven perfectly symmetrical antler points on each side of its head will likely produce equally impressive male offspring.

Not all bull elk or buck deer, however, have a trophy rack of antlers, no matter how old they live. Some mule deer, for example, may never grow antlers better than two points on one side and three on the other, measuring 16 inches at the widest. That’s not a trophy to many hunters.

A study of white-tailed deer compared the offspring of yearling bucks with relatively large branched antlers versus yearlings with only spikes. Because both sets of deer were captive in the controlled experiment they were fed identical diets. The yearlings with larger antlers sired only five percent spikes, while the spike yearlings produced 44 percent spike antlered yearlings.

One of the conclusions from that study is encouraging hunters to shoot spike bucks if a deer herd is to be improved.

As for nutrition governing size, scientific evidence points to diet greatly influencing antler growth. One study of mule deer has shown that in wet years, which means increased availability of food, there are fewer spike bucks and a larger number of yearlings with forked antlers.

What’s it all mean? Given the right forage conditions and genetics, buck deer or bull elk can sprout impressive antlers.

But it’s still up to the hunters to find them.