07 Mar

Frozen Food: Winter Woes for Cougars

Cougar

It was dark, and cold. Under cover of night, F61, an adult female mountain lion currently followed by Panthera’s Teton Cougar Project, padded softly back to her kill. Drew Rush, on assignment for National Geographic’s article “Ghost Cats” had visited while she was away, and set up a motion-triggered camera to photograph her upon her return.

After a quick examination of the camera, F61 inspected her kill. It was an elk, and she had carefully covered it in snow to minimize its chances of detection from competitors.

But something had changed. What was once soft, fluffy snow had hardened in her absence, entombing the elk carcass in an impenetrable igloo instead. Luckily there was one area of the kill covered in a thinner layer of snow, one she could punch through in order to feed. And over the next few days, F61 wedged her head deeper and deeper into the hole, attempting to eat as much of her elk as she could.

(Photograph by Drew Rush/National Geographic)

Each season presents its challenges. In summer, for instance, bears steal numerous meals from cougars. But it’s winter now, and bears are hibernating in northwest Wyoming where we work.

Now, cougars can eat in peace more often. Nevertheless, heartless cold temperatures and snows frequently steal meals from mountain lions instead. Mountain lions typically cache their kills beneath a mound of snow but when temperatures drop precipitously at night, this behavior frequently backfires.

Unlike foxes, coyotes, and wolves, cougars lack the strong feet and stout claws for intensive excavation. Thus, when snows become thick ice that hinders their ability to feed, cougars abandon their kills to hunt again. (The below video shows a red fox excavating an igloo hiding a bighorn sheep carcass. The mound was created by F49, an adult female mountain lion.)

A red fox excavates an igloo hiding a bighorn sheep carcass. The mound was created by F49, an adult female mountain lion tracked as part of Panthera's Teton Cougar Project, to minimize the chances that scavengers would detect her kill.

In winter, its common for cougars in our study area to lose access to at least half of every elk they kill. Cougars tend to feed on one side of an elk at a time, and by the time they are finished with one side, the other can be wedged beneath a solid layer of compressed snow and ice, and completely inaccessible.

This is important to realize because it helps us understand the foraging ecology of cougars. Cougars need to kill a specific amount of meat to meet their energetic demands for living, but they kill much more than this. In summer, bears steal their kills, and in winter, cold weather and snow steal their food. Thus, cougars are often unable to consume all of what they kill, and so they must kill again more quickly. This is, of course, bad news for elk and deer.

F61, an adult female mountain lion, straining with everything she has to reach deep beneath the layer of ice to reach just a bit more of the elk she’d killed and cached beneath the snow. (Photograph by Drew Rush/National Geographic)

F61 was not a cougar to give up easily. She stretched and reached as far as the small hole in the ice allowed. With toes stretching and limbs flailing to either side, F61 tipped herself forward and upward, looking as if she were break dancing, or attempting advanced yoga. Alas, she eventually abandoned the carcass to scavengers and set off in search of fresher game. It can be tough being a cougar.

Follow F61 and other cougars on Facebook.

Learn about Panthera’s Teton Cougar Project.