Born to be Big At birth, an elk calf weighs about 35 pounds (16 kg) and can gain two pounds (one kg) a day for the first few weeks. At the start of its first winter, an elk may weigh five times as much as when it was born. Cow elk can weigh more than 500 pounds (225 kg), stand 4-1/2 feet (1.3 m) at the shoulder, and measure 6-1/2 feet (2 m) from nose to rump. An average bull weighs 700 pounds (315 kg), stands 5 feet (1.5 m) at the shoulder, and measures more than 8 feet (2.4 m) from nose to rump.When winter begins, cows and bulls separate, rejoining their previous herds. In the late spring or early summer, cows will leave the all-female herd to give birth. The single calf (twins are rare) is born between late May and early July. Calves weigh about 35 lbs at birth and their fur is dotted with cream-colored spots along their backs. A calf can stand after the first 20 minutes of life, but it can not run fast or for long periods of time. For the first few weeks, the mother will hide her calf in thick brush and graze at a distance so she won't draw attention to its presence. The calf stays motionless, stirring only when the mother returns for nursing. This is when the calf is most vulnerable. Bears, coyotes, mountain lions and wolves will be looking for it. The calf's spotted coat helps to camouflage it and the calf itself produces no odor, making it harder to find. If the female elk feels her calf is threatened she will rush to its defense, using hooves and teeth to drive the predator away. When the calf is approximately 3 weeks old, both it and its mother will rejoin the female herd. Once within the herd, the calf's chances of survival are greatly improved.