The smaller bulls will be run off by the older male, who can be quite aggressive and dangerous while in rut. They have been known to tear down deer fences and even kill other animals with their fighting. The smaller bulls will herd together and attempt to breed the cows from time to time. Breeding starts at the first sign of cold weather. The gestation period is nine months.
Single births are most common, but occasionally twin births do occur.
The newborns are up and running soon after birth. The spots seen on the coats of the very young elk are shed by about three months of age. Antlers are the bony growths on the foreheads of most male deer. They grow from pedicles, permanent bony outgrowths of the frontal bone. Antler growth requires protein and calcium, with testosterone being the controlling factor and part of the cycle of growth.