Question: what kind of animals are at yellowstone national park

title: List of animals of Yellowstone
text: Bulls grow antlers annually from the time they are nearly one year old . When mature , a bull 's `` rack '' may have 6 to 8 points or tines on each side and weigh more than 30 pounds . The antlers are usually shed in March or April , and begin regrowing in May , when the bony growth is nourished by blood vessels and covered by furry - looking `` velvet . '' Antler growth ceases each year by August , when the velvet dries up and bulls begin to scrape it off by rubbing against trees , in preparation for the autumn mating season or rut . A bull may gather 20 - 30 cows into his harem during the mating season , often clashing or locking antlers with another mature male for the privilege of dominating the herd group . By November , mating season ends and elk generally move to their winter ranges . Calves weighing 25 - 40 pounds are born in late May or early June .