Pumas in the Rocks, Pumas in the Grass

Three years after becoming entranced by the world of the world’s smallest camel, the vicuña, Arthur Middleton returns to San Guillermo, Argentina with photographer Joe Riis to learn more about these unusual animals and to share their adventures here.

A vicuña has to make hard choices every day. Sometimes the choice is whether to eat or to be eaten.

Yesterday we visited a place called Aguito del Indio, where a small spring-fed stream flows from beneath a red rock wall down a broad, sandy canyon. Lush greenery crowds in around the stream’s upper reach. Aguito del Indio offers both the food and the water a beleaguered vicuña badly needs.

But there’s a catch: its rocks also provide the perfect cover for a puma to hide and strike. So Aguito del Indio is a vicuña boneyard. Along both sides of the stream are a litter of weathered bone shards, old ribcages, twisted strips of hide, and sun-bleached skulls.

There are even some fresh kills in the nearby grass.

The choice a vicuña encounters here (risk it all for nourishment, or play it safe and go without) may hold the key to understanding a lot of what we see vicuñas doing at San Guillermo. We see one fascinating behavior, the vicuña’s daily migration, unfold every morning near one of the park’s big meadows. The meadow is full of knee-high grasses, and surrounded by a broad gravel plain.

Photo by Joe Riis.
Vicuñas graze on the Aguito del Indio. (Photo by Joe Riis.)

As we sip on our coffee, the first dull light of day slowly lights up hundreds upon hundreds of golden-brown vicuñas, dotted all across the plain. Some of them remain bedded; others have already roused. As the sun grows brighter, the vicuñas begin a familiar ritual–their daily migration to feed in the meadow.

They travel in small family groups, gathering numbers as they head for the meadow from miles around, but when the first vicuñas arrive at meadow’s edge, no one wants to step in first. What if a puma crept in there overnight? A daring few–perhaps the hungriest?–test their luck. They’re jumpy, craning their long necks to see into the grasses ahead. And if no pumas strike, the others start to pile in behind them.

Once inside the meadow, the vicuñas graze happily all day. Males fight. Youngsters play. If it’s hot, females roll around in the mud a bit. But without fail, one hour before sundown, they begin to migrate back out into the plain. By nightfall the meadow, so full of life all day, falls silent. After all, who wants to be in that tall grass, in the dark, when the puma comes?

Can you see the puma? Because it can see you. Photo by Joe Riis.
Can you see the puma? Because it can see you. (Photo by Joe Riis.)

We see something similar round the rocky canyons. Few vicuñas venture there, even though there is good grass to eat. In fact, Emiliano’s research shows pumas are a major reason for dense grass growth in the canyons: by scaring vicuñas, the predator seems to protect these “risky” places from overgrazing.

More and more, these are the reasons why ecologists think the big cats may help shape ecosystems more strongly than other predators, like the canids. Since cats tend to hide in specific places that prey can learn to avoid, they indirectly relieve grazing pressure on nearby plants–perhaps benefiting other animals that depend on them as well.

Worldwide, many of the big cats are in decline so even though we are a world away from the lands of the lion, tiger, or jaguar, we hope what we learn at San Guillermo can help open our eyes to what we might be losing.

Read All San Guillermo 2014 Posts




Meet the Author
Arthur is a wildlife ecologist based at Yale School of Forestry and Environmental Studies. He studies the predator-prey interactions and seasonal migrations of large mammals in the Rocky and Andes Mountains.