I just did a bit of research at the CA Fish and Wildlife site and elsewhere and found some interesting data. Please correct me if I am wrong, but it appears that before lion hunting was banned in 1972, fewer lions were killed by hunters than are killed today by Fish and Wildlife and ranchers killing depredation lions. Back before 1972, a hunter in the field or hikers or tree huggers almost never saw a lion. Today it is fairly common. Lion vs. livestock problems were also quite rare when lions were hunted but not today.
Cal Fish and Wildlife recently conducted a truly detailed and probably accurate study of lion populations in the state and came up with 4500. A ballpark guess for San Diego County is 100 but that is only a guess and many experts feel it is well on the low side. Also, researchers estimate that lions kill about 1 deer a week [when deer are available] and that equates to 200,000+ deer eaten here in CA each year, and the total population of deer in CA is about 500,000. Do the math. But when deer are not available, lions eat dogs, cats, turkeys, rabbits, etc. and they have to greatly increase their home range in order to find enough small game to eat and that means moving into the suburbs.
And finally, my wife and I lived in Encinitas before moving to HI and then to Fallbrook. We were on the corner of Saxony Road and Quail Hollow, with a 100 acre preserve behind us and canyons leading into the preserve. We had ducks in a pond in an enclosure and chickens and turkeys. One night, the ducks started quacking loudly so I assumed coyotes or a bobcat and grabbed my rifle and spotlight. I immediately woke my wife and had her look. I shined the light on the varmint and told her, "Look at the tail. Check out how long it is and the black tip. Nobody will believe you." It was an adult lion, probably a large male. When she tells that story to some of our city slicker friends, they smile smugly and say, "That was a bobcat." She then asks them to explain the long tail with the black tip and they tend to change the subject.
Pay close attention to the elections coming up. Wouldn't surprise me a bit if the San Francisco types in Sacramento introduce a bill banning all deer hunting in the state because mountain lions are running out of food.