Asked by Maggie R.

Why would the population of mountain lions increase in the past 10 years even though humans were expanding into the mountain lion's habitat?
Answered by Ms. Sue
It's possible that something happened to the lions' predators. In California, mountain lion bounty hunting is now banned, and some experts believed that's what has led to an increase in its population.

http://tchester.org/sgm/lists/lion_attacks.html