Along with heading to the mountains to see the gold aspen leaves, a must-do for a lot of Coloradans in the fall is to hear bull elk bugle. The male elk’s high-pitched bellow signals the start of the rut — mating season — and is a beckoning call for wildlife-watchers and a harbinger for hunters of the chase to come.

But a new analysis by a sportsmen’s group says the Rocky Mountain icon is increasingly under pressure from human encroachment into the areas it uses to migrate, seek food and shelter, and give birth. The Theodore Roosevelt Conservation Partnership’s report looks at the impact of the state’s booming outdoor recreation and the more than 40,000 miles of mapped trails used by hikers, mountain bikers, ATV riders and others.