Section 3 - Elk Though the Seasons
When food is abundant and elk are healthy, they do what many animals do -- they play. They dash about leaping and kicking, squealing and calling to each other. They race in circles, taking turns to splash through ponds and puddles. Then, as suddenly as they started frolicking, they quiet down and return to feeding.
Instinct drives elk to behave in ways that promote the survival of their species by protecting and promoting their ability to reproduce. Their seasonal movements, their choices of calving grounds, feeding and resting places, even their social groups promote their reproductive fitness. How does play behavior fit into this? Biologists say that play is fun for animals, and also helps young animals develop the coordination and strength they need to evade predators. Play also helps keep adults fit.
Elk behave in similar ways wherever they live, but the details vary with specific habitat. For this discussion about behavior, we will follow a generic group of elk living in the mountains of the western United States.
On the Move
Lengthening days, warming temperatures, and melting snow all signal the start of spring movement for many elk in the Rocky Mountain region. They follow the melting snow to find newly exposed fresh vegetation at increasingly higher elevations. This migration may take only a few days or it may go on for two months.
Bulls begin to migrate first. They move more quickly and to higher elevations than cows and young elk. Cows often begin migrating before they give birth to their calves. They may return to the same range every year, using similar routes and river crossings. They stop to give birth and allow their young to grow for several weeks. By late June or July, they've resumed moving into higher country where they will find rich summer food.
Not all elk migrate. If they have enough food, water, shelter and space, they may stay in the same area year round. For example, some elk in Yellowstone National Park stay near thermal areas during all seasons because the warmth from under the ground keeps snow melted and plants growing even in the coldest of winters.
New Elk Arrive
Most cows have been pregnant since early October, but the most rapid fetal development occurs in the last six weeks. (Gestation is 8-1/2 months.) The young are born from mid-May through early July, depending on where the elk live. Calving time generally coincides with the period when the most nutritious food is available.
When a cow is ready to give birth, she often leaves the group to find a site that other elk seldom visit. This strategy helps her avoid predators that may have learned to hunt in places that elk frequent. She may select a site in an open, brushy area or perhaps in an area of thick trees.
A newborn calf is slow to get up on its feet and can't run fast or long. Instead, camouflaging coloration (its spotted coat) and an apparent lack of odor enable it to escape detection by most predators. The cow also helps hide the calf by eliminating any signs of her calf that a predator might detect. After giving birth, she devours the placenta and any soil or vegetation soaked by the birth fluids. She continues to clean the site by eating the young's feces. To avoid leading predators to her young, she grazes away from the hidden calf and returns to nurse it only a few times a day. If a predator approaches, though, she will attack or try to lead the animal away from the calf.
Even with all these strategies, a cow often loses her calf to bears, coyotes or other predators in the first three weeks. If a calf survives its first few weeks and joins the group with its mother, it is usually out of danger for a while. By that time, the calf can run fast enough to escape most predators, and it benefits from the safety of the group.
By July, cows and calves begin forming nursery groups. The size depends on where they live -- smaller groups might gather in a densely forested area, larger groups might gather in open valleys and prairies.
Within the larger herd, calves form smaller groups that center around one cow at a time. This cow seems to act as a "baby-sitter" for the calves while their mothers graze and rest. The calves respond as a group to the signals of the baby-sitter, a strategy that eliminates confusion when danger threatens and so helps protect the calves. It also allows the cows to spend most of their time eating, and to react quickly and better protect themselves.
By now, calves are safe from most predators. But if grizzly bears are part of the ecosystem, these powerful predators can catch any elk -- young, sick or merely unlucky -- that cannot flee fast enough.
Bulls usually spend the summer alone or in small groups at high elevations. In such places, they find rich forage, cool breezes and resting areas with fewer annoying insects.
Eating All the Time
Elk eat almost constantly during the summer. They keep feeding morning, afternoon, evening and even in the middle of the night, although they feed more often at dawn and dusk. They are building up fat in preparation for the mating season and then the long winter. If people had to eat and chew their food as much as elk do in the summer, we would have less than 10 free minutes every hour for other activities.
One elk feeding alone is vulnerable to predators, but elk feeding in herds are much safer. At least one animal will have its head up, listening and watching for trouble while the others eat. Elk are even safer when they are resting and ruminating.
Elk tolerate heat much better than the mule deer that often share the same summer habitat. Deer seek shelter and may stop feeding during a hot spell, but elk can sweat more to cool off. Still, during a hot spell, they may retreat to north and east slopes to take shelter among the trees. They may also stay near water, and sometimes they stand in a stream or pond. Elk will sometimes wallow and cover themselves in mud, which absorbs body heat as it dries and also protects them from biting insects. Elk might also head to cooler, breezier high country.
Bull elk also carry around "air conditioners" that cows don't have -- antlers. Air cools the blood flowing through the velvet, which then helps to cool the bull's body.
The Rut Begins
Shortening days, cooling temperatures, and snow in the high country all signal the start of the rut (elk mating season). Elk begin moving to lower elevations. Mature bulls move in among a group of cows and calves. These groups, called harems, are the scene of constant action from September through October, and sometimes through November.
A harem is usually smaller than the large cow/calf herds of summer and lacks the male yearlings. These adolescent males are usually driven off by the mature bulls or by cows intolerant of their presence. Sometimes, however, these young males remain near the harem, and often seem confused and unsure of their role.
By September, a bull's antlers are fully grown and almost ready for the displays and battles to come. The bull removes the tattered velvet and polishes his antlers by rubbing them on trees, shrubs and even the ground. Vigorous rubbing also releases his pent-up energy and leaves behind his scent to let other elk know that he is around.
If mud is available, bulls also wallow during mating season. A thorough mud covering cools off an over-heated bull, spreads his scent evenly over his body, and makes him look even more imposing.
The biggest bulls are animals in prime physical condition and may be six to eight years old. Younger bulls may try to butt in -- they are physically able to breed by their second summer -- but they seldom get a chance to mate.
When the rut begins, bulls begin to bugle. The sounds they make are among the more haunting and beautiful in nature, as memorable as the howls of wolves and the calls of loons.
A cow listens to the bugle for clues about the bull's size. A bugle, like a human voice, varies with the individual, but the older, larger bulls usually bugle more loudly than their young rivals. Their bugles advertise their presence and fitness to both females and other males. They also bugle to announce or accept a challenge from another male.
A cow can also tell the quality of a bull by the size of his antlers and body. During the rut, she has plenty of opportunity to observe the bulls as they "show off" to each other.
When bulls display their antlers and body, they are gauging each other's fitness and ability to defend the right to mate with the cows. A young male will probably retreat rather than engage in a fruitless battle with a mature bull. But bulls more equal in size typically confront each other.
Before a fight begins, the two bulls display their dominance by bugling and thrashing the ground with their antlers. They might march side by side, then suddenly turn, walk farther, or begin their fight. Then the bulls lock antlers and shove each other with all their might.
Fighting is a show of strength, not a battle to the death, but bulls do get hurt. If they stumble while their antlers are locked, one animal may be stabbed by the other's antlers. Mature bulls often sustain injuries every year.
When the cows come into estrus ("heat"), the mating begins. A bull elk must be ready -- a cow is receptive for mating less than 24 hours. She won't be willing to mate again until her second estrus cycle arrives in 20 days. Cows can have up to four estrus cycles each season, but most cows become pregnant during the first or second cycle.
On the Move Again
Harems disband when the rut ends. Cows regroup, and bulls of all ages may gather in bachelor groups. Both sexes eat as much as they can in preparation for the coming winter, a time of sparse food.
Elk will stay on their summer range as long as possible because the food is much more nutritious than what they will find on their winter range. But as snow begins to pile up in the high country, the elk are on the move again. They travel until they find slopes with less snow or no snow at all.
Cows and bulls often occupy different areas of their winter range. Bulls may retreat to high, snowy meadows where the food is adequate but not especially nutritious. A group of cows and calves may inhabit a south-facing slope that is free of snow and covered with nutritious grass. This behavior ensures better survival for the cows and calves.
In the winter, elk eat less and rest more. Some biologists believe this is a logical strategy for conserving energy and fat reserves. Other biologists suggest that elk may need to rest more because they have to ruminate, or digest, their food more. Their winter food -- dried grasses and twigs -- is harder to digest than their summer food. And if they live in snow country, they actually expend more energy if they must paw through snow to obtain that food.
When the snow gets too deep -- usually more than one foot (30 cm) -- elk may look for shrubs to eat or move to forested areas where they can eat twigs and bark. Thick stands of trees also shelter the elk from wind and cold.
Winters with heavy snow aren't necessarily a problem for elk. But if the winter is extremely cold, has exceptionally deep snow, and lasts a long time, many elk may die. Those that survive a severe winter are still in danger because their fat reserves are depleted, and the remaining vegetation is at its yearly nutritional low point. An adult elk may starve in that lean time before the new growth of spring begins.