Yesterday, a friend was telling me about a trip into the backcountry of Washington State. He and a buddy hiked 7 miles over a mountain into a remote canyon and made camp. The next morning, he heard a whistle off in the distance, so he whistled back, thinking it might be another hiker approaching their camp. A minute later, a cougar appeared at the edge of the clearing, and it stood there intently staring at my friend and his buddy.
The guys had no firearms with them, and not wanting to share the camp with a mountain lion, they decided to pack it up and get out of there. They quickly grabbed their gear and headed up the mountain trail away from the cougar. But when my friend looked back, he noticed that the cat was following them, keeping a distance of about 150 feet. Every time he looked, the cat was still there, and it stalked them for the full 7 miles back to their truck.
When my friend was telling me about this incident, he said he felt certain that if he had been alone the cougar would have taken him down. That's probably true. This cat seemed to have no fear of the men, and was willing to track them for a long distance up and over a mountain, possibly just waiting for an opportunity to take one of the men if they got separated too far from each other.
The normal pattern for a cougar is to single out one victim, but to hang back or avoid people who are in groups. However, it has been known for a mountain lion to attack a hiker or a mountain biker even when there are other people not far away. If there is any separation of the humans, the cat might make his move.
So the rule in cougar country is to never hike or bike alone, and stay close to each other in your group. A mountain lion is one of the few wild animals that will actually stalk a human with the intent to kill. Now that it's legal to carry firearms into National Parks, you might consider packing a defensive weapon.
And if you hear a whistle, you might want to wait a minute and figure out what's making the noise before returning the call. Who knew?