This information is taken from the Rocky Mountain Elk Foundation. Hope it helps.
All in the Family
Elk and other members of the deer family belong to a group of animals called ungulates, the Latin word for "hoof." All ungulates have hooves. This large group used to be considered one order, but now "ungulates" refers to two distinct orders, Artiodactyla and Perissodactyla. The number of toes is the most obvious difference between the orders. Artiodactyls (elk, deer, bison, pronghorn, peccary) have an even number of toes. Perissodactyls (horses, elephants) have an odd number of toes.
Elk, moose, caribou, white-tailed deer and mule deer all belong to the order Artiodactyla and to the deer family, Cervidae. The males of these species grow and shed antlers each year. (Female caribou also grow and shed antlers.)
Like other ungulates, members of the deer family are herbivores -- they eat only plants. Their diet may include grasses, forbs (low-growing, short-stemmed plants), shrubs and trees (including limbs and bark).
Members of the deer family must eat and watch for predators at the same time. Elk fulfill these double needs by gathering in herds. In a group, at least one animal is looking up while others are eating. Even the animals that are feeding are constantly twitching and turning their ears to listen for unusual or warning sounds.
Some deer family members migrate, following their food sources as the seasons change. Some caribou migrate hundreds of miles twice a year as they follow the seasons. Most elk that live in mountainous country migrate to lower elevations as snow covers the higher elevations, then return as snow retreats in the spring and summer.
Wherever you live in North America, you are likely to be near at least one member of the deer family. White-tailed deer live throughout the lower United States; mule deer browse in the western states and provinces; moose inhabit riparian areas (banks of rivers and other bodies of water) across the north; and caribou can be found in northern Idaho, Alaska and Canada. Elk used to live across North America, but these days you are most likely to find them in the western states and provinces.
Each spring, male deer and elk begin growing antlers from bony bumps on their skulls called pedicles. 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. They are light and easily damaged until they completely mineralize in late summer. A soft covering called velvet helps protect the antlers and carries blood to the growing bone tissue.
If you look closely at a deer or elk antler, you'll see grooves and ridges on it. These mark the paths of veins that carried blood throughout the growing antlers. When blood stops flowing to the antlers in August, they 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.
An antler grows 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.
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.
Elk and other members of the deer family eat tough plants such as grass or twigs that most other mammals can't digest. Elk digest these plants in multi-chambered stomachs, a trait of the suborder Ruminantia. (Cattle, sheep and their wild cousins are also ruminants.) The root of the name comes from "rumen," the first of three or four chambers of a ruminant stomach. These chambers create a system for digesting tough plant fibers and extracting the maximum nutritional value from them.
To understand how this "super stomach" works, imagine a cow elk as she nips off twigs, clips leaves and crops grasses. This constant biting, pulling and clipping sends as much as 15 pounds (7 kg) of tough plant fiber into the elk's stomach each day. The unchewed material slides into the rumen, the first chamber. There bacteria and protozoa begin breaking down the plant material. Then the elk regurgitates her food (the cud) and ruminates (chews cud thoroughly).
When the cud is completely chewed, the elk swallows it again. The food particles pass through the rumen and into the reticulum, the second chamber, for even more digestion. Then the food passes into the omasum, the third chamber, where water is squeezed out and absorbed into the elk's body. Finally, the food passes into the abomasum, the fourth and "true" stomach, where it is broken down to the molecular level so that it can be absorbed by the intestine.
Secrets of Teeth
Like other deer, adult elk have sharp incisors for biting off plants, and broad, flat molars for mashing plants. Molars line both the upper and lower jaw, but incisors occur only on the lower jaw. Elk also grow two canines (also called tusks, ivories, whistlers or buglers) in the upper jaw.
When biologists want to determine an elk's age, they look at the teeth, not the antlers. Teeth are a better gauge because antler size can vary depending on the health of the bull, and cows don't grow antlers. To "age" the teeth, biologists place a cross section of an elk's tooth under a microscope and count the annual growth rings.
The type of teeth in an elk's mouth and the amount of wear they show can also indicate the animal's approximate age. To figure the age of a young elk, a biologist observes how many adult teeth have replaced the "baby" incisors and premolars. This transition is completed by the end of the third year. Older elk can be identified by the amount of wear on their molars because chewing tough plant fiber will wear down even the sturdiest of teeth.
In the Open
Although we primarily see elk in mountainous and forested terrain today, they are also well suited to open spaces. Some scientists believe that an elk's body and senses reflect adaptations for the lifestyle of a herd animal that once roamed the plains for its food.
An elk's long legs are packed with powerful muscles designed for speed and endurance. A strong heart and lungs pump blood and air to those muscles to keep them moving, and move is what elk do to find enough food to eat throughout the year. They also need to escape predators such as wolves, mountain lions and grizzly bears.
Elk have keen senses that enable them to identify each other over long distances and to detect approaching predators. Unlike human eyes that can see precise images, an elk's eyes are designed to detect movement, even the slightest shifting of grass as a predator approaches. To an elk, knowing that something is moving closer is more important than identifying the kind of animal approaching. And because their big eyes are on the sides of the skull, elk can see what is happening ahead of them and beside them, as well as most of what is going on behind them.
Likewise, their big ears can twist forward and back to capture faint rustlings and other sounds of movement. Elk also seem to have a superb sense of smell. Combine the sharp senses of a group of five, 10, or even 50 elk and it's easy to understand how they avoid predators.
In the next two sections, "Where Are The Elk" and "Elk Through The Seasons," you'll discover how their habitat and behavior also help them to stay safe.