In Patagonia, the rules are simple.

In order to eat, a puma must use stealth.

For her prey, staying alive requires vigilance.

She holds the power of life and death.

But even for this master hunter, survival is the ultimate challenge.

Late afternoon in the southern Andes, it's a time when this predator and her prey maintain an uneasy truce.

The guanacos know that she mainly hunts at night. So they should be safe at least until the sun goes down.

Like all cats, the puma has superb night vision.

But if the guanacos detect her scent, the hunt will be over.

She circles around to stay downwind of her quarry.