MAMMOTH HOT SPRINGS, Wyo. — Yellowstone National Park officials are warning the public about aggressive elk as the calving season sets in.

Across Wyoming, cow elk will be much more territorial and may run toward individuals.

The best way to avoid a conflict is to stay alert, says the park.

An elk calf bedded down under a boom lift. Photo: Jacob W. Frank // NPS

“Look around corners before exiting buildings or walking around blind spots: cow elk may bed their calves near buildings and under cars,” said the park.

In the case that an elk run towards you, find shelter in your vehicle or behind a tall, sturdy barrier as quickly as possible. Attacks can be unprovoked and unpredictable.

Calving season or not, always keep at least 25 yards (23 m) from elk.

The elk population in Yellowstone is 10,000 to 20,000 animals, dispersed in six to seven different herds. The population across the greater Yellowstone ecosystem is estimated at 30,000-40,000 elk.

Abundance of the northern Yellowstone elk population, 1923–2022. Shaded area indicates uncertainty about the trend with respect to random under- and overcounting. These results underestimate the true population size because they do not account for imperfect sightability. Photo: NPS

Elk mate during the rut, which occurs annually in September and October. Cows birth a single calf, usually May through late June, weighing about 30 pounds.

A thirty-two-minute old elk calf in Mammoth Hot Springs in 2010. Photo: Jim Peaco

For protection from predators, the calf has a spotted coat and an instinct to lie completely still when danger approaches. Within two weeks the calf is able to keep up with the mother, and both rejoin the herd.