America’s national parks offer lots of exciting outdoor activities and stunning scenery. They’re also home to incredible wildlife, including moose, bears, bighorn sheep, elk, and more.

Outdoor Guide recently compiled a list of the “best US National Parks to visit if you love watching wildlife.” Colorado’s Rocky Mountain National Park was included in the round-up.

According to Outdoor Guide, Rocky Mountain National Park is home to “one of the most astounding occurrences in the natural world.” The elk rut, known as “Elktober,” is when thousands of bull elk move to Rocky Mountain National Park to find mates during the fall. The elk have been known to block traffic or shut down trails. Bulls will bugle loudly and lock horns in their quest for a mate, putting on quite a show for spectators.

Estes Park even hosts Elk Fest, a festival that includes live music, food trucks, and bugling contests. As always, it’s important to view the animals from a distance and never approach or feed them.

Check out Outdoor Guide’s full list of national parks to visit if you love watching wildlife here.