Seasonal Elk Activity by TR Michels
Because of their large size and food requirements, and because mountainous habitat forces many herding animals to wander during the summer and fall in search of food, elk often migrate when severe cold or snow depths make it difficult for them to survive and find food. The migration is usually from high, cold or snow covered regions, where the elk cannot find food; to lower, warmer elevations with less snow and more easily found food. Different elk herds may prefer different elevation depending on snow depth and forage availability. In Wyoming wintering elk are often found at 6000-7000 feet, while in Idaho they may be at 2000-3000 feet. In the Pete King area of Idaho bulls were found at 2859 feet and cows with calves at 2770 feet. In the Sun River area of Idaho elk were found at 5200 feet in December, 5105 feet in January, 5250 feet in February and 5095 feet in March.
Elk often use lower areas as winter feeding grounds, but with the advance of spring and new growth, the animals begin a slow migration back to summer ranges, and the cows usually calve along the way. In north Yellowstone the spring migration occurs as early as April while seventy-five miles south, in north Jackson Hole, it may occur in May. Roosevelt Elk on Afognak Island, Alaska migrate during May and June. The timing of the migration may vary yearly by several weeks from year to year, and from herd to another herd in different locations.
The distance herds migrate, and the speed of the migration also varies, from one to as many as eighty miles, and from one day to a week. Different sexes and age classes also show differences in migration. Bulls generally migrate first in the spring, because they don’t need to provide extra nutrition for the calves like the cows do. Bulls and some cows can usually be found following the receding snow line to higher elevations. The bulls often arrive at their summer range several weeks before the cows.
The gestation period of elk has been reported to range from 247 to 265 days, with an average of approximately 255 days. Cows usually halt their spring migration for calving from mid-May to mid-June, depending on their geographical location. Elk in northern regions have a calving season of 20-45 days, while Tule elk in California have a calving season of more than 50 days. Calving areas are often between open brushy areas that offer food and coniferous forests that offer concealment and escape. The actual calving site is usually a low depression on a gentle slope; southern slopes are often preferred. Water within a quarter mile is often a key factor in choosing a calving site. Some calving areas are traditional and are used every year. Individual cows remain away from the herd 10-20 days before resuming their migration from mid-July to June. The yearling calves are usually forced away from their mothers at this time, but they often stay in the vicinity of the herd. The young bulls are seldom tolerated, and they may not migrate as far as the older animals. They often wander in search of new range during their first 3 years.
During the summer cows and calves rely heavily on grass and sedges, which make up 50-60 percent of their forage at this time. Browse and forbes each make up another 20 percent of their diet. Calves rely more heavily on succulent forage than the cows. In their search for forage the cow/calf herds frequent open meadows with nearby shade and cover, and spend up to 85 percent of their time feeding and resting with very little travel.
The older bulls do not usually associate with the cows during the summer. Because they look different with their racks (which makes them susceptible to predation) their strategy is to stay away from the cows and calves. They need to renew the fat reserves they used up over the winter and gain enough fat to get them through the upcoming rut. They also need enough minerals to grow their rapidly developing racks. To supply these needs the bulls seek out areas with high quality foods. Because of the need to avoid predation, and with the need to find high quality foods the bulls may travel extensively over large home ranges of up to 40 square miles.
Yearling bull elk may start growing racks as early as late May. They often grow a rack with one long point on each side. This point, which is actually the main beam of the rack, may reach fifteen inches or more in length. An occasional yearling will grow a 2×2 rack, and I have seen yearlings with racks having three to five points per side. The racks of yearlings often have tines of differing lengths or numbers of tines on each side. Some hunters refer to bulls with these uneven racks as “raghorns.” When a bull elk grows only one point they are referred to as spike bulls, and people often refer to any one-year-old bull as a “spike.” Two-year-old bulls often start antler growth in late April or early May, and continue for 105-125 days, with the velvet being shed from middle to late August. They often grow 4×4 or 5×5 racks. They usually cast their antlers from mid to late April.
Bulls over the age of three to four years old may shed their antlers and begin growing new racks from mid March to early April, and continue growing their racks for 130-150 days, shedding velvet as early as the first week of August. Up to fifty percent of these bulls may have five points per side while the rest may have six or more points per side. In one study, bulls over the age of four all had five points or more per side. The antler growth of three year old and older bulls may take up 150+ days. I sold a pair of 6×7 shed antlers from a 5-year old bull on April 6th one year; the antlers had dropped off the week before.
Up until the age of seven most of the nutrients taken in by the bulls are used for muscle and bone growth. By age seven the bulls have usually reached full body size, which is when some of the nutrients can be diverted to antler growth. This is when the greatest growth in antler mass and length normally occurs; and is known as the “seven year antler spurt.” Because of this antler spurt bulls between the ages of 9 and 12 can be expected to grow the largest racks. After the rut the prime age bulls usually leave the cow and calf herds to seek high quality forage to get them through the winter. If these prime age bulls rejoin the cow herds they may retain their antlers 10-20 days longer than normal due to renewed sexual interest.