What should you do if you hear a mountain lion warning sound while hiking in the wilderness?

If you hear a mountain lion warning sound while hiking in the wilderness, you should stay calm, make yourself appear larger by raising your arms or opening your jacket, and slowly back away while facing the lion. Do not run or turn your back on the animal. If the mountain lion approaches, make loud noises, throw objects, and try to intimidate it. If attacked, fight back aggressively. It is important to report the encounter to local authorities afterwards.