But the high, snowy Yellowstone Plateau would make for hungry winters, so the elk head for lower elevations in October. Some 10,000 to 15,000 head for the sheltered northern end of Yellowstone National Park. As many as 12,000 more spend their winters at the National Elk Refuge near Jackson. Elk refuges and winter feeding areas attempt to address the problem that for nearly six months a year, elk need to live in the same sheltered, low-elevation grasslands that make good sites for towns, ranches and farms. The bull's antlers grow from two permanent bones, called pedicles, that attach to the elk's skull.
Antlers take about four months to grow.
They harden over the summer, fall and winter until, dry as old wood, they snap off close to the bull's head. Then the next set begins to grow. Of the four subspecies of elk that still survive in the United States, the Rocky Mountain elk found in Yellowstone country have the largest racks. A pair of antlers from a big bull may weigh 40 pounds. Elk like green grass, so they're often seen on open grassy hillsides.