Mountain lions — also called pumas or cougars — are the top predator (other than humans) in the Santa Clara Valley. They live alone and are most active at night. Mountain lions are big: males can be more than 8 feet long and weigh over 120 pounds. Pumas can climb trees and may be found up to 50 feet up a tree. They primarily eat deer but also eat raccoons, birds, foxes, and mice. Cougars need large amounts of connected open spaces for hunting, water sources, and den sites. Mountain lion attacks on humans are exceptionally rare. If you encounter a lion, look big and stay with others. If attacked, fight back and be loud. Do not try to run away.