When a big buck deer or bull elk ambles into view this hunting season, consider how it got such large antlers.
Genetics and nutrition are the two biggest factors in how large an animal's antlers will grow. Generally, genetics determine the form of antlers while nutrition dictates their size.
Deer and elk grow antlers, not horns. Most hunters know the difference, know that antlers only grow on male members of the deer family and know 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.
That a buck deer or bull elk inherits the genes to grow big antlers seems easy 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, grow a trophy rack, 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 5 percent spikes, while the spike yearlings produced 44 percent spike-antlered yearlings.
One of the conclusions from this study is that shooting spike bucks should improve the antler genetic of a deer herd.
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 the increased availability of food, there are fewer spike bucks and a larger number of yearlings with forked antlers.
So given the right forage conditions and genetics, buck deer or bull elk can sprout impressive antlers. But it's still up to hunters to find them.