Spring, summer and fall are the best times for viewing wildlife in Rocky Mountain National Park. Spring is birthing season for many large mammals in the park; elk, mule deer and moose are seen in many areas with their newborn calves.
It is very likely to see wildlife in the summer—they like to soak up the sun as much as we do. Elk are seen frequently throughout the summer in meadows and at or above the treeline. Big horn sheep are seen from May to mid-September, mule deer are commonly seen in open meadows just about anytime of the year, and moose are often spotted in the willows on the west side of the park, in Kawuneeche Valley.
And lastly, fall is mating season for many large mammals, commonly called the rut. It is typically from mid-September to mid-October, and consists of large groups of elk in one area, the bull elk occasionally fighting to win a harem, and the sound of elk bugles echoing against the granite mountains.