Why do people call the cops when they see a mountain lion? What law is the lion breaking? Is it trespassing? Speeding? Vandalizing?

There's going to be more of this as mtn. lions have to expand their territory due to population expansion. This is because the lions currently have no natural predators. Unfortunately, their numbers will eventually have to be culled by hunting. Beautiful animals, but when they get too hungry they may salivate after humans.

I've always had a large sign on my back porch saying 'No Mountain Lions Allowed.' I've never had any problems.

The mountain lion was on her front porch for 15 minutes and she did not take a picture?

Unless these individual mountain lions are taught by aggressive non-lethal measures to once again fear humans and therefore avoid human contact there will be no alternative but to kill them. That is a horrible and unnecessary outcome.

Learn from history - read about how Boulder Co ignored this problem until someone was killed and then how it developed an aggressive program of reintroducing fear of humans into these animals:

The Beast in the Garden: A Modern Parable of Man and Nature by David Baron

[Portion removed; be respectful of other posters]

@Peter, I get that your position purports to actually save rather than risk more mountain lion lives.

However, the problem though is generally with humans and our ever-encroaching development -- not the natural fauna.

Give it a rest - my position is that we should learn from history, i.e. Beast in the Garden, rather than repeating the mistakes made elsewhere.

I keep scratching my head every time I read of someone calling the police because they saw a mountain lion. There's nothing the police can (or should) do. The reality is that if you live in the Santa Cruz Mountains (and the foothills) there are mountain lions in your neighborhood EVERY DAY. They use the creeks as their main path of travel. Most of the time you don't see them. But they are there. People in La Honda see them all the time (and they show up on the myriad of wildlife cameras that people out here have put up.) You should take precautions EVERY DAY. But we don't call the cops every time we see wildlife (except maybe when the wild life at Apple Jack's gets out of hand...)