Summary (tl;dr)

A woman was found dead on the Crosier Mountain Trail in Larimer County, Colorado, in what authorities suspect was a rare fatal mountain lion attack, leading to the euthanasia of two mountain lions and the closure of area trails.

Essential Background

Mountain lion attacks on humans are considered extremely rare in Colorado, with only 28 reported attacks since 1990 and the last suspected fatal incident occurring in 1999. Despite their rarity, mountain lions are common in the forested and rocky terrain of Larimer County, especially in winter when they follow deer and elk to lower elevations. Notably, there was a prior report in November where a man running on the same Crosier Mountain Trail had to fight off a mountain lion.

The Full Story

On Thursday, January 1, 2026, hikers discovered an unresponsive adult woman on the Crosier Mountain Trail in unincorporated Larimer County, Colorado, near the small community of Glen Haven. A mountain lion was observed near the body by the reporting hikers, who then scared the animal away by throwing rocks. Colorado Parks and Wildlife (CPW) officers, alongside local law enforcement and firefighters, responded to the scene and launched an extensive search for mountain lions. Two mountain lions were located, one at the scene and another nearby, and both were subsequently euthanized in accordance with CPW policy for wildlife involved in attacks on humans. A necropsy will be performed on the animals to determine their involvement in the attack, check for abnormalities, and test for neurological diseases. Trails in the Crosier Mountain area remain closed as authorities continue to search for a reported third mountain lion.

Why It Matters

This incident is significant as it marks what is believed to be the first fatal mountain lion attack in Colorado in over 25 years, prompting serious concerns about public safety for hikers and outdoor enthusiasts in areas with active wildlife populations. The event underscores the potential dangers of encountering apex predators, even in areas where human-wildlife interactions are typically uncommon. The closure of popular trails highlights immediate safety measures being taken, while the euthanasia of the involved animals reflects wildlife management protocols aimed at preventing further incidents. It also reignites discussions around coexistence with wildlife and the importance of awareness and preparedness when venturing into natural habitats.

Geographic Location

• Crosier Mountain Trail, Unincorporated Larimer County, Colorado, United States (fatal mountain lion attack)
• Glen Haven, Larimer County, Colorado, United States (nearby community to the attack site)