Interesting facts you may not know about Idaho's deer and elk

You may know how to spot them, identify them, track them, shoot them and cook them, but did you know these things about Idaho's deer and elk? 

Mule deer

Mule deer were uncommon in Idaho prior to white settlement. Early journals and observations from settlers and other historical documents rarely mention mule deer, but they frequently mention bison and bighorn sheep. Bighorns were also commonly depicted in Native American rock art throughout Idaho, but seldom mule deer.

Regulated deer hunting in Idaho predates statehood. The first hunting season for deer in what is now Idaho (then part of the Idaho Territory that included Idaho, Montana and part of Wyoming) was implemented in 1863, which closed deer hunting between Feb. 1 and June 30. The State of Idaho’s first regulated deer season was in 1893, and a hunting license was first required in 1903. 

Most mule deer in Idaho seasonally migrate twice yearly between summer and winter range (and back again). The longest documented mule deer migration is over 240 miles from winter range in the Red Desert of Wyoming to summer range near Island Park. Researchers believe mule deer learn migration routes from their mothers and continue that same route for the rest of their lives. (Source: Mule Deer Foundation)

Despite being associated with Idaho’s deserts and mountainous country, mule deer are good swimmers and won’t hesitate to swim across large rivers, large lakes and reservoirs. 

Mule deer have up to 11 subspecies, which includes their close cousins, blacktail deer. Today, mule deer and subspecies inhabit every state west of the Mississippi River (except Hawaii) and as far south as Baja, Mexico. (Source: Mule Deer Foundation)

Elk

Unlike deer, which drop their antlers during winter, elk antlers typically remain until the growth of the new antlers pushes off the old ones. Full grown elk antlers can weigh up to 40 pounds per set, and can take up to 160 days to fully grow. A bull’s antlers increase in size annually until at least its sixth set, then may increase or decrease in size according to several factors, including health and nutrition. (Source: Montana State University)

Idaho hunters have harvested more than 20,000 elk annually in nine of the last 10 years, which is a feat duplicated only one other time in Idaho’s history from the mid-1980s to mid-1990s.  

Elk have two canine teeth commonly referred to as “ivories.” Biologists believe ivories are the remnants of saber-like tusks that ancestral elk used in combat. (Source: Rocky Mountain Elk Foundation)

Elk are the most vocal of Idaho’s big game herbivores. They communicate through a variety of vocalizations. The most commonly heard are bulls bugling in the fall, but cows frequently converse among the herd through mews, chirps and barks. A cow elk can recognize her calf by the unique tone of its squeal.

In 1909, elk populations in Idaho were so alarmingly low that a moratorium on elk hunting was declared in parts of the state. Elk herds from Yellowstone National Park were translocated to restore Idaho’s population, which started in 1915 by railcar, then continued to various parts of the state until 1940.

White-tailed deer

Whitetails are not only the OG deer species of North America, they are also the oldest living deer species on earth. Their direct ancestors reached North America by crossing the Bering Land Bridge into Alaska, and fossils very difficult to distinguish from modern whitetails have been found in Florida that date back 5 million years. (Source: National Deer Association)

The size, shape and location of a whitetail’s eyes give it vision 310 degrees around themselves, and their night vision is as good as their day vision. So if you think whitetails have eyes in the back of their heads and keep vampire hours, you may be right. 

Idaho’s whitetails are widely perceived as homebodies who live in a fairly small area year round. However, data from Fish and Game’s GPS collar research has shown some does traveled 20-25 miles to have their fawns, then returned months later with their fawns in tow. 

Whitetail fawns are small at birth, typically weighing 6-8 lbs, and some subspecies, like Florida's Keys deer, may weigh about 2 lbs at birth. But whitetail fawns can double their weight in their first week, and commonly weigh 10 times their birth weight by their first winter. (Source: National Deer Association)

Idaho’s historic deer harvest has long been dominated by mule deer. In 1975, Fish and Game started tracking the harvest by species, and in 1994, whitetails topped mule deer for the first time ever. Since then, whitetail harvest has exceeded mule deer five more times, most recently in 2023. Mule deer continue to be the larger portion of the harvest in most years, but the percentage of whitetails has crept up due to healthy populations and increased interest in hunting them.