Mountain Lion: Sensing Humans

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I recently wrote about some remote camera photos from southeast Peru that illustrated mountain lion scent-marking behavior (see post Camera Trap: Puma (Mountain Lion)). I commented that if our sense of smell was better, we might have been able to detect this behavior without the use of digital technology. Well, other photos indicate that our other senses are not as good as the senses of the other large mammals living in the forest and that they react to us even when we don’t know they’re there!

For example, some photos taken by a remote camera illustrate that our sense of hearing, along with our sense of smell, is relatively weak. The first rapid sequence of 10 photos shows a mountain lion (also known as a puma or cougar) walking up the trail with its ears partly laid back and its forehead wrinkled, in what I interpret as an expression of unease. Seven minutes later, the remote camera took photos of two field workers arriving to change the camera’s batteries and memory card. Because this camera is set in a rugged area where the trail is quite steep, I suspect the humans were less than 1,000 feet (300 meters) away when the photos of the puma were taken. I interpret these photos to indicate that the mountain lion knew the humans were nearby and that it was walking up the trail to avoid them. The trail is covered with moss and leaves, so footprints are virtually impossible for humans to see, and the men had no idea they were so close to a mountain lion until they saw the photos from the remote camera. I’m sure the mountain lion, and other animals in the area, were very aware that humans were present.

Fortunately, for the time being humans do not often go into the forests where we have set our remote cameras, and humans haven’t had a big impact there. That may be changing. Because the Inter-Oceanic Highway has been built through the area, it is now easier to move large machinery into the area and remove resources from the area. There are now a lot of people inside and outside of Peru who are interested in extracting natural resources that they couldn’t access before, and the human impact on the forests and the wildlife is growing. This is one of the reasons that we’re working in this area, in collaboration with the Botanical Research Institute of Texas. Although the Cusco regional government has proposed conserving part of the area for sustainable use by local residents, and a non-governmental organization has proposed placing part of the area under its protection, it’s not clear that any action will take place soon enough, or be strong enough, to conserve these forests and wildlife. For now, all we can do is wait and see, using advanced technology to compensate for our limited sensory systems.

Russ Van Horn is a scientist with the San Diego Zoo Institute for Conservation Research, leading our Andean bear conservation program.