Hunting Mountain Lions with Motion-triggered Cameras at the Grand Canyon

We were in for a long, bumpy ride down a washed out, rocky, rutted, very bad road. We crawled slowly along the southern border of Grand Canyon National Park towards the mountain lion cache site.

I'd gotten stuck on the same road earlier, when the SUV I was driving bottomed out over a large rock jutting out of the middle of the road, followed by a hole the size of a small crater, all situated on a steep incline. The erratic floods of the monsoon season can wreak havoc on unmaintained roads. I blame them for the hole, but I don't have anyone to blame for the rock. I used the jack and a few strategically placed rock piles get the car moving again. Luckily on this trip we had higher clearance.

The road crosses leisurely out of the National Park, into tribal land- owned and sometimes guarded by the Havasupai- before crossing Forest Service land and then leisurely making its way back to the Park, seeming to me to making a circuitous point about the arbitrary quality of such boundaries. There weren't any guards at the desolate entrance to Havasupai, so we let ourselves in and headed toward the former Pasture Wash Ranger Station, a long-abandoned run down cabin on a wide plateau about 35 miles west of the Grand Canyon Village, as the crow flies.

The South Bass Trailhead is a little ways east of the old ranger station, a long lonely trail to the banks of the Colorado River. Technically a hiker could do a "rim to rim to rim" trip, crossing the river and taking the North Bass Trail up along the Powell Plateau to the top of the North Rim, and then coming back the same way, but they'd have to arrange to get across the mighty Colorado. I've heard of hikers serendipitously crossing paths with boaters who will give them a lift across the river. Trusting that they'll find a ride back on their return is a leap of faith.

Our destination lied above the canyon's rim. We left the car near the ranger station and started hiking along an old telegraph route, heading toward Pt. Huitzil. My companions were a Park Ranger and the park's Wildlife Biologist. The ranger had been out this way over the weekend for a bit of hiking when he and his companion came across the carcass of a yearling elk that hadn't been a carcass for very long. And it had been cached under a rock pile, presumably by a mountain lion.

He stopped by the old train depot that served as the wildlife office to tell of his discovery. Naturally, we asked him to lead us to it. We thought that a fresh mountain lion cache would be the perfect opportunity to test out our newest mountain lion monitoring gadget, a remotely-triggered camera.

I'd moved to the Grand Canyon that summer to work on a mountain lion research project. Most of my research to date consisted of setting up scent stations to collect mountain lion DNA. I also searched for tracks, collected scat, responded to observations, and listened to countless tales of historic and current mountain lion sightings that came my way.

One thing I hadn't yet seen was a fresh kill site. I knew that mountain lions cached their prey, but I didn't really know what that looked like. I had a friend in Missoula who'd been to a kill site once with another biologist friend. He described it in highly unscientific terms, "You know how they pile leaves and shit all over the carcass? Well they don't just make one pile. They make a bunch of little piles. They tear out the guts and shit and put them in one little pile over here, then they have a bunch other shit in piles over there. There's piles everywhere. They're freaky, I'm tellin' you."

I couldn't wait to see that freaky shit myself. As we meandered off-trail through the junipers toward the cache site, we noticed a few archeological artifacts. Okay, I didn't, but my hiking buddies did. I don't have an eye for them. My eye is usually trained on the ground scanning for tracks, scat, scrapes, fur, pellets, feathers, any signs of wildlife. I could trip over a metate in the middle of an ancient ruin surrounded by petroglyphs and not even notice any of it.

But the ranger had an eye for artifacts- one of which was the smallest arrowhead I'd ever seen. He told me it was called a "bird point." We took turns examining the tiny relic of the past before he carefully placed it under a large rock where it would be protected. I don't know if he was more concerned about it being destroyed by the elements, swiped by greedy collectors, or thinking about coming back for it later. Whatever the case, it was relatively safe for the time being. We hiked on.

The cache was on the eastern slope of a small dry wash with very little cover. The yearling elk that had been covered with dirt, twigs, and mostly rocks. Mountain lions have a tendency to cover their kills with whatever material is at their disposal, which wasn't much in this dry wash.

We investigated the various piles (its true, lions often take out the stomach, and its contents, and cache them away from the rest of the carcass), documented all the lion sign: tracks, scat, drag marks. We determined that this was the work of a solitary adult lion who ambushed the young elk first jumping on his back, breaking his neck, and then, based on the puncture wounds on his muzzle, suffocated him before slitting open his belly and diving in to a hearty meal..... literally.

I hooked up the camera to the remote sensing equipment inside the heavy-duty metal housing, inserted 4 D-cell batteries (this was in the early stages of remotely-triggered camera development- this model would be considered a dinosaur now), and mounted the bulky casing to the trunk of a juniper with wire. The 35 mm camera inside the casing would be triggered by motion, or more accurately changes in heat, detected by the sensors that also reside inside the casing. Each time the sensors detect motion, the camera takes a snapshot of whatever is in front of it at that moment. We were hoping to get photos of a mountain lion feeding at the cache site, and to see what other scavengers might benefit from the kill.

We left the site and arrived back at the car shortly before dusk, which was right around the time that this curious cat popped into the view of the camera lens:

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