The Passing of a Titan

An intimate portrait of F109, an adult female mountain lion tracked by Panthera’s Teton Cougar Project in northwest Wyoming.

Contrary to popular belief, mountain lions are not all the same. They are as distinctive in personality as we are. Some are bold, others stick to the shadows. Some are social, others avoid interactions. Some hunt elk, some prefer smaller fare. Some are productive, successful mothers that rear numerous kittens to young adults, and others never raise a single kitten to independence. It’s productive females like F109 that are so important to the future of mountain lion populations.

F109, an adult female mountain lion followed by Panthera’s Teton Cougar Project, was exceptional by every standard. She was near impossible to catch with hounds. She was a master of interwoven fallen trees and would leap to mount them, weaving loops across trunks without ever touching the ground. She would climb trees when dogs were close, and leap from one canopy to another, only to descend some distance away. We reveled in the fact that she was safe from hunters; her intelligent evasive strategies left their hounds (and ours!) in drooling befuddlement. F109 was the cat we’d tell stories about around the fire; we revered her tenacity and her indomitable spirit. Whenever a hike was long and hard, we’d say to ourselves, “at least we’re not on a 109 capture!”

F109 raised several litters of bouncing kittens to independence, all the while traversing the highest, most rugged terrain our study area in northwest Wyoming had to offer. She survived encounters with bears and wolves, as well as encounters with humans and bull elk. She endured bitter cold and landslides. She showed us exactly what a fortified den looks like (See A Fortress for Kittens). In 2013, she was the first and only mountain lion among those we’ve followed to successfully kill and consume a wolf (See Hunters or Hunted? Wolves Vs. Mountain Lions). Each winter, she also killed several bull elk, which can weigh greater than 700 lbs— more than 8 times her size. She was the first mountain lion we caught on video interacting socially with another mountain lion (See Solitary is not Asocial: Social Interactions Among Mountain Lions), and in recent years she interacted with other mountain lions some 28 times. Over the 6 years we studied her, we gathered data on 195 prey she killed and consumed. Twenty of those kills provided us the opportunity to film and study vertebrate scavengers and document more mountain lion social interactions. F109 taught us what it means to be a successful mountain lion, and as we continue to analyze data and reflect upon our time in northwest Wyoming, she will continue to teach us more.

F109 died this month of natural causes, old age and disease, at an incredible 12 years of age. In a hunted population such as this one, her long life is worthy of recognition. Her collar betrayed her final resting place, and we ascended 2,500 feet to find her high on Sheep Mountain, in the center of her territory. On high, we crossed a final snow-covered meadow to enter the copse of trees she’d chosen.

The mountain was quiet when we arrived, the air crisp and cool. There were nearby signs of a red squirrel, but it did not chatter at our approach or as we lingered over F109’s frozen body. F109’s death will go unnoticed by most, but her absence leaves a hole in the Jackson ecosystem. The local mountain lion community is more diminished for her passing. Our lives, I’m convinced, are more impoverished as well. Thank you, F109.

Look for updates on mountain lions we follow on Facebook. Thanks for reading.

Changing Planet


Meet the Author
Mark Elbroch is Director of the Puma Program for Panthera, a US-based non-profit that conducts science and conservation action to promote wild cat conservation worldwide. He has contributed to puma research in Idaho, Colorado, California, Wyoming, Mexico, Washington and Chile. He earned his PhD at the University of California, Davis, where his dissertation research focused on puma ecology in Patagonia in the presence of endangered humeul deer. He has authored/coauthored 10 books on natural history ( and numerous scientific articles published in peer-review journals.