Statement on the Possible Mountain Lion Attack in Colorado

DENVER – Animal Wellness Action and the Center for a Humane Economy — two organizations at the forefront of the Prop. 127 campaign to outlaw the trophy hunting of mountain lions that voters rejected in November 2024 — issued the following statement after news reports of a possible fatal lion attack in Larimer County, an area north of Estes Park:

“We extend our deepest and most heartfelt condolences to the family and friends of the victim, in what Colorado Parks and Wildlife authorities are investigating as a suspected mountain lion attack,” said Wayne Pacelle, president of Animal Wellness Action and the Center for a Humane Economy. “We are deeply saddened by this loss of life, and discussions on the exceedingly rare nature of such incidents does little to console people grieving over this tragedy.”

This fatal incident occurred during Colorado’s ongoing lion trophy hunting season, which stretches from November 24, 2025, to March 31, 2026, with a quota of 610 lions. The vast majority of lions are taken with the aid of packs of dogs, typically run by guides who conduct the hunts and offer a shooting opportunity to a fee-paying trophy hunter. Advocates of the hunt have argued that aggressive lethal control improves public safety and reduces conflicts with people, pets, and livestock.

In the wake of an emotionally wrenching moment like this one, it is important to understand how these events connect to state policies and to gauge whether refinements in policy can reduce risk.

“A growing body of peer-reviewed scientific evidence strongly challenges the premise that trophy hunting of lions reduces risks of dangerous human-lion encounters,” said Jim Keen, DVM, PhD, author of a 2024 scientific review of mountain lion hunting and public safety entitled “Aggressive Trophy Hunting of Mountain Lions May Exacerbate Human Conflicts with Wildlife.”  Dr. Keen is the director of veterinary science for the Center for a Humane Economy and a former U.S. Department of Agriculture research scientist and faculty member at the University of Nebraska School of Veterinary Science and Biomedical Research.

“It may be counterintuitive, but multiple field-based studies demonstrate a positive association between the number of lions killed and subsequent increases in reported conflicts with people and domestic animals,” added Dr. Keen. “Selective killing of older male lions through guided trophy hunts, aided by the use of packs of dogs, destabilizes lion populations, increases the proportion of lions in a population who are juveniles or younger animals, and ultimately raises the likelihood of conflicts with people, pets, and livestock.”

The effect of trophy hunting in reducing the average age of animals in a population is well understood. Trophy hunters preferentially target large, dominant adult males—the individuals most critical for maintaining stable territories and social structure and who are most skilled at killing deer and elk. Removing these animals creates territorial vacuums that are rapidly filled by younger, less experienced males. These younger lions are more likely to roam widely, enter suburban and rural communities, prey on pets or livestock, and encounter people, thereby increasing the risk of dangerous interactions.

Colorado’s mountain lion hunting program is among the most aggressive in the West, with long seasons and high kill quotas. In recent seasons, trophy hunters take approximately 500 mountain lions, with males constituting the larger share of animals killed. Despite this heavy lethal pressure, there is no credible scientific evidence that such policies improve public safety. Instead, the data indicate that aggressive trophy hunting may undermine safety by disrupting the very population dynamics that naturally limit conflict.

“Trophy hunting is often falsely sold to the public as a safety measure, and today’s incident reminds us that the fatal lion attacks on people occur more frequently in areas with extensive hunting than areas without hunting,” Pacelle added. “Younger lions are traditionally involved in more encounters with people, and trophy hunters, especially those led around by guides, target older animals more skilled at killing traditional prey. That allows an opening for younger lions and it’s that group that produces more social instability and conflicts with hikers, hunters, or foothill or mountain communities.”

Mountain lion attacks on humans remain exceedingly rare, especially in regions and states without any hunting of lions. “How humans manage apex predators matters,” adds Dr. Keen. “California ended trophy hunting of mountain lions more than 50 years ago and instead relies on non-lethal management and targeted removal of problem animals, and it has human–lion conflict rates lower than states with intensive trophy hunting.”

As Colorado authorities investigate this heartbreaking incident in Larimer County, Animal Wellness Action and the Center for a Humane Economy look forward to working with CPW personnel, commissioners, lawmakers, and a range of stakeholders to address an important policy question: whether current trophy hunting policies provides any buffer of protection for public safety, or whether its effect is to increase the remote risk of human-lion encounters.

The synthesis of the literature on human-wildlife conflicts and the effects of trophy hunting on those conflicts can be found here.