Oh, deer

The other morning, just before sunrise, seven mule deer walked through the front yard. It was a great sight for several reasons.

For one, in many north central Montana prairie areas, mule deer have been largely replaced by white-tailed deer. Not everywhere, but in some places.

Generally, mule deer cycle through population upswings and downturns more widely than whitetails. So when mule deer numbers drop, they drop. And whitetails can fill in the gap.

Also, when whitetails do have population declines, they rebound quicker because they often have greater reproductive rates — mule deer does usually have a fawn, occasionally twins. Whitetail does more often have twins and occasionally triplets.

It was also nice the other morning to see mule deer on their historic prairie. Lewis and Clark are credited with first describing the mule deer in September 1804 in what is now South Dakota.

William Clark wrote that fall day that one of the expedition’s hunters killed a deer with “ears large and long.” The expedition knew the eastern white-tailed deer, but they had never seen a mule deer.

They later learned much more about this new species of deer, such as its preference for rough country and open ground rather than woodlands near the river.

Almost exactly two years later, in August 1806, on the expedition’s return trip, and in nearly the same spot as their first encounter, they killed their last mule deer. Lewis and Clark realized they were at the eastern limit of the High Plains and would soon see mule deer no more.

 Another reason it was good to see mule deer the other morning was the one buck in the group. He looked young and sleek, due to his fine summer coat, and his antlers were several inches tall and wrapped in what looked like velvet.

Antlers are fascinating feats of nature. They are the only mammalian appendages capable of complete regeneration. Some amphibians can have portions of their bodies severed only to re-grow the lost limb or tail. Not so with mammals, except for antlers.

Growing antlers are bone covered by blood vessels, nerves and fine, velvet-like hair. Triggered by daylight length, antler growth begins when sex hormones, like testosterone, are at minimal levels.

The rise of the animal’s testosterone near the end of summer causes the antler bone to die and shed the velvet covering. The antlers are then ready to use for fighting and attracting females, coinciding with the peak of breeding, mid- to late-November for mule deer. By late winter, testosterone declines, the headgear falls off, and within a few weeks the process begins anew.

And as to the age-old question — what causes some but not all deer to grow enormous antlers? The easy answer is age, genetics and nutrition. Or to put it another way, on a mature buck, genetics determine the form of antlers while nutrition dictates their size.

Oh, yes. The final reason it was great to see seven mule deer walk by the front of the house? They passed by the newly fenced vegetable garden in the back of the house.

Bruce Auchly is information officer for Montana Fish, Wildlife and Parks Region 4.