Some of the data I was reading yesterday indicated about half of the annual fawn kill was due to lions and about a quarter was coyotes (all CA data). But there were many healthy does also taken by lions, counter-intuitive to the rule of thumb that predators only take the weak, old or sick among the herds. They also migrate with the herds, overlapping each other's territory, bucking the usual trend to keep to one large area as resident predators. Like our deer, our lions are always on the move.
Doubtless, the presence and growth of lions isn't helping things. But I'm curious as to why this would be a significant contributor over many years. What level of deer population would reduce lion numbers? How has the lion population stayed in control in the past? Is the absence of grizzlies or wolves (who may steal lion kills) allowing lions to grow beyond their normal carrying capacity? Too many questions, for sure. And dynamic, complex systems can't easily be reduced to singular causes so much as the interplay between many causes.
Personally, I lean toward Daniel Quinn's "law of limited competition." The basic idea is that in the natural world, animals may compete to the fullest extent of their ability but they may not lay claim to all the food nor may they wage war against their competitors. All animals follow this rule (including humans before civilized cultures took over). So the lions and coyotes are safe from me. Unless, of course, I suddenly decide that I want a nice coyote pelt for some reason.
I appreciate the idea somebody posted about traditional bowhunters not being a significant problem compared with rifle hunters. I've only taken 2 deer in my life -- both with a rifle. But I certainly agree that if all hunters were limited to more primitive (and quiet) methods, then there would be fewer hunters and many fewer kills. My rifle kills were over and done with so quickly, I was left with a slight feeling of disappointment. I'm more proud of stalking in close to several deer this year (all does, it turned out) than in my kill with a rifle last year.
Now if only we could convince our wise and loving representatives to put a moratorium on rifle hunting only...