North American Elk, or Cervus elaphus, are split by some biologists into six subspecies:
- Rocky Mountain (Rocky Mountain West, now transplanted to other locations) – largest antlers of all subspecies
- Roosevelt’s (Coastal Pacific Northwest) – largest in body size of all subspecies, but not antler size
- Tule (Central California) – smallest body size of all subspecies
- Manitoban (northern Great Plains)
- Merriam’s (Southwest and Mexico) – Extinct
- Eastern (east of the Mississippi) – Extinct
Once found all across North America, elk have historically lived in many types of habitat. They’ve learned how to survive with different foods, weather, cover and neighbors. In fact, elk once lived in almost every variety of habitat on this continent except for the driest western deserts and the most humid southeastern forests. Some biologists believe there are no true subspecies of elk; that any North American elk transplanted to a different area will soon take on the characteristics of native elk to that area within only a few generations and without interbreeding. In other words, that size, color and antler appearance are strictly a result of environmental factors such as forage toxicity rather than evolutionary sub-speciation.
Rocky Mountain Elk: Master of Mountains, Prairies and Hardwoods
Most of the elk that survived early settlement and overhunting lived in the Rocky Mountains. They escaped by hiding out in this rough and rugged terrain. Elk from Yellowstone National Park were hauled by truck and railcar to restore herds around the nation, which is why most elk in North America are Rocky Mountain elk.
Tule Elk: A Unique Beast to California’s Marshes and Deserts
Temperatures top 100 degrees, the few oak trees provide little shade, and water gets scarce, but that doesn’t bother California’s tule elk. While most elk must live with harsh winters, tule elk face the opposite challenge. Winter brings plenty of greens to eat in California’s Central Valley, while summer’s heat burns up most of the forage and bakes away the water. Tules have adapted to go longer without water than other elk can. Their extra-long rows of teeth help them chew up the desert’s coarse grasses and shrubs, and in the fall they munch on acorns. Tule elk also hang out in marshes filled with “tules” — the tall, cattail-like plants that give these elk their name.
Roosevelt’s elk: Ghosts of the Jungle
Amidst the dark, looming cedars and firs lurks a large shadow of an animal. It’s the Roosevelt’s elk of the Pacific Northwest. These elk hide out in the thick coastal rainforests where they easily eluded early hunters. Roosevelt’s plump up on berry bushes and willows all winter, munching more grasses and small leafy plants in spring and summer giving them the largest bodies of any elk. They also have the darkest coats, which help them blend into their shady environment.
Bull: Male elk
Cow: Female elk
Calf: Baby elk
Spike: Yearling bull elk
Size and Weight
Newborn calf: 35 pounds (16 kg)
Cow: 500 pounds (225 kg) (Tule elk: 300 lbs., Roosevelt’s elk: 600 lbs.)
4 1/2 feet (1.3 m) at the shoulder
6 1/2 feet (2 m) from nose to tail
Bull: 700 pounds (315 kg) (Tule elk: 400 lbs., Roosevelt’s elk: 900 lbs.)
5 feet (1.5 m) at the shoulder
8 feet (2.4 m) from nose to tail
• Summer: copper brown
• Fall, winter and spring: light tan
• Rump patch: light beige
• Legs and neck often darker than body
Over the course of a year, elk may experience temperatures ranging from 100° F (38° C) to minus 40° F (minus 40° C). Somehow they have to keep their body temperature steady no matter how extreme the weather. How do they do it? After all, they don’t have the luxury of peeling off a shirt or zipping up a parka. Elk have only two coats–one for summer and one for winter. Their coats help them regulate their body temperatures.
Twice a year, they shed every hair on their body. Their spring shedding is noticeable because ragged tatters of old winter hair dangle like long scraggly beards from their necks and sides. By July their winter coat is completely replaced by their summer coat. This summer coat is a thin, sleek layer of short hair that is the color of copper.
Their summer coat lasts only two short months. The elk don’t look like they’re shedding in September, but they are. Summer hair is falling out as the long, thick winter coat begins growing in. The longer, darker hair begins appearing on their heads and necks — they have manes again. And their summer coats give way to winter tones of light brown and tan.
An elk’s winter coat is five times warmer than its summer coat. The summer coat has just one short, thin layer of hair. The winter coat consists of two layers — thick, long guard hairs and a dense, woolly undercoat.
If you split open a guard hair and look at it through a microscope, the inside looks like the honeycomb in a bee’s nest (see photo above). Thousands of tiny air pockets fill each guard hair. That makes them waterproof and warm. This warm winter coat is so thick that it can keep snow from melting on an elk’s back.
The catalyst that causes coat-switching takes its cue not from increasing or decreasing temperatures, but from the increasing or decreasing light available each day — the photoperiod. This is the same cue that causes leaves to fall in autumn.
Elk have other tricks for staying warm in winter. For example, elk can make their hair stand on end, trapping more air and creating a thicker coat. They can also tuck their legs beneath them when they lie down so they lose less heat through their legs, chest and belly.
What’s the best way for elk to stay warm? They seek thermal cover — on cold, sunless days or at night, they head for the north and east slopes. There they bed beneath thick trees. The trees hold warmer air near the earth, catch snow before it hits the ground, and break the wind. On sunny days, elk move to open south and west slopes.
From the Yukon Territory to Arizona, elk usually have the right coat for winter. But even with a warm winter coat, elk still need appropriate habitat — no matter what the season.
- Calves are typically born in late May through early June
- Calves are born spotted and scentless as camouflage from predators
- They spend their first few weeks hiding motionless while their mothers feed
Summer: grasses and forbs
Spring and Fall: grasses
Winter: grasses, shrubs, tree bark and twigs
- Elk may supplement their diet at licks, where they take in minerals that may help them grow healthy coats and produce nutritious milk
- An elk’s stomach has four chambers: the first stores food, and the other three digest it
- An elk’s top two canine teeth are called ivories
- Scientists believe ivories are remnants of saber-like tusks that ancestral species of elk used in combat
- Most hunters save ivories as a memento of the hunt
- Only male elk have antlers
- Bulls shed and grow a new set of antlers every year
- New antlers are covered in fuzzy skin called velvet
- Antlers harden by late summer and the velvet peels away
- By September, antlers are solid bone
- A set of antlers on a mature bull can weigh up to 40 pounds
On top of every bull’s head are two pedicles – specialized bone-follicles covered with skin. Antlers grow out of these pedicles each spring and summer. Increasing daylight elevates the level of the hormone testosterone in the animal’s blood, which triggers the growth of antlers.
Antlers begin as layer upon layer of cartilage that slowly mineralizes into bone. A soft covering called velvet helps protect the antlers and carries blood to the growing bone tissue. If you look closely at an antler, you’ll see grooves and ridges on it. These mark the paths of veins that carried blood throughout the velvet.
Velvet is tender and easily damaged. Injuries to velvet can cause a bull to have malformed antlers, sometimes just for that year, sometimes for the rest of their lives. Antler-cells grow faster than any other kind of bone. It can grow up to one inch (2.5 cm) per day during the summer. Biologists are studying antlers in hopes of learning the secrets of rampant cell growth–secrets that may unlock cures to various forms of cancer.
When blood stops flowing to the antlers in August, they mineralize and harden, and the velvet falls off or is rubbed off. The hardened antlers are composed of calcium, phosphorous and as much as 50 percent water.
Testosterone continues to build within bull elk into September, prompting them to seek out harems of cows, fight with other bulls, and mate. But by October, testosterone levels slowly begin dropping until early spring when the antlers drop off. The pedicles bleed a little right after the antlers fall off, but they soon heal. And as spring green-up begins, the cycle begins again as a new set of antlers soon sprout from the pedicles.
In his second year, a bull elk usually grows slim, unbranched antlers called spikes that are 10-20 inches (25-50 cm) long. By the third year, antlers begin developing tines that branch from the main beam. By the seventh summer, a bull’s antlers may have six tines each, weigh as much as 40 pounds (18 kg), and grow to a length and spread of more than four feet (1.2 m). Why would an animal need to carry around a rack of antlers that weighs so much? A large rack identifies a bull that is successful in finding food, lots of food.
A bull must consume huge amounts of nutrients to obtain the energy and minerals needed to grow antlers as well as the energy to carry them around. Large antlers also identify a bull that is able to defend himself against other bulls and against predators. This information is of great interest to female elk (cows) because they will mate with the strongest, most successful males — usually the bulls with the biggest antlers.
The Differences between Antlers and Horns
Elk have antlers as opposed to horns. What are the differences between the two?
- Made of bony core covered by a thin layer of keratin, the same material as your fingernails
- Slow growing and permanent; they are not shed each year
- More like daggers than branches
- Usually grown by both sexes
- Usually grow in yearly “rings” that mark the animal’s age
- Fast-growing bone that is shed each year
- Usually grown only by males (both sexes of caribou grow antlers)
- Often branched (but the number of points does not signify age)
- Cows, calves and yearlings live in loose herds or groups
- Bulls live in bachelor groups or alone
- During the rut, cows and calves form harems with one or two mature bulls
- When alarmed, elk raise their heads high, open their eyes wide, move stiffly and rotate their ears to listen
- If a harem cow wanders, a bull stretches his neck out low, tips up his nose, tilts his antlers back and circles her
- Elk threaten each other by curling back their upper lip, grinding their teeth and hissing softly
- Agitated elk hold their heads high, lay their ears back and flare their nostrils, and sometimes even punch with their front hooves
Elk Talk: Vocalizations
Elk are among the noisiest ungulates, communicating danger quickly and identifying each other by sound.
- High-pitched squeal: Newborn to its mother, who recognizes her calf by its voice.
- Bark: Warning of danger.
- Chirps, mews and miscellaneous squeals: General conversation among the group.
- Bugling (bellow escalating to squealing whistle ending with grunt): Bull advertising his fitness to cows, warning other bulls to stay away, or announcing his readiness to fight.
- Elk also use body language. For example, an elk displays dominance by raising its head high.
Bull elk bugle to attract cows and advertise their dominance to other bulls
Cows bark to warn others of danger
Cows mew to keep track of one another
- Elk breed in the fall
- Bulls gather cows and calves into small groups called harems
- Bulls wallow in mud to coat themselves with urine “perfume” to attract cows
- They also bugle and rub trees, shrubs and the ground with their antlers to attract cows and intimidate other bulls
- Bulls aggressively guard their harems from other bulls
- Sometimes, bulls wage violent battles for a harem, occasionally even fighting to the death
As August draws to a close 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.
Elk Range and Habitat
• Prior to European settlement, more than 10 million elk roamed nearly all of the United States and parts of Canada
• Today, about one million elk live in the western United States, Wisconsin, Michigan, Minnesota, Missouri, Pennsylvania, Arkansas, Kentucky, Tennessee, Virginia and North Carolina, and from Ontario west in Canada
• Food, water, shelter and space are essential to elk survival
• Elk live in a variety of habitats, from rainforests to alpine meadows and dry desert valleys to hardwood forests.