When I lived in AZ, My first house was out in the country near Prescott, in a large secluded valley with the Agua Fria river running through it. Near the river were large stands of cottonmouth trees and about 1/3 mile away up river was an old smelter sight and EPA Superfund site. Near the site the river cut through some deep canyons with some natural caves and rock ledges.
Occasionally, I heard a cougar doing it's creepy screaming woman call. I found some tracks in the river bank that were larger than my closed fist; a big cat.
One evening, a group of javelina came through my property and my old lab and the wife's yappy dogs gave chase. The Javelina would have none of it and started fighting back. I grabbed my AR and ran out on the deck just as the dogs were headed back to the house in pure terror. Javelina were in close pursuit so I shot one of the javelina.
It was pretty big, about 50lbs or so. I dragged it out into the sage brush about 100yds from the house and left it.
The next day I decided to go move it further away from the house and it was gone. Apparently the cougar had come in and carried it off without leaving any drag marks. Impressive.
Most cougar attacks that I know of are done by young males that are driven out of their territory by a senior tom when they reach adulthood. They are usually desperate and prey on children and dogs.
However, this past year, there have been two fatal cougar attacks here in the Northwest involving adults. One was a female jogger and the other a male cyclist. Cougars surprise their prey by jumping on them and grabbing the back of the neck first, while raking the body with their claws. They are not trying to scare you off; they want to kill you as quickly as possible.
Mountain lions are for lack of a better way to put it, an entirely different beast. Sorry for the obvious pun.
Lions are thick where I live and I've been working among them for 14 years. In that time I've seen two of them, heard them scream once, observed fresh tracks and half buried kills more times than I've bothered to remember. I recreate in the woods also on my free time, so I've been in their territory a fair amount.
You are correct about young cats. As prey numbers decrease or more mature and dominant adults take over a territory they tend to push younger cats out and those cats will sometimes wander hundreds of miles in search of a new territory. They are lost and exploring so often they don't know what the hell they are doing.
Your account of the javelina incident doesn't surprise me. The strength to size ratio of an adult lion is absurd. One part of the career I've chosen that I love is that I get to meet a lot of experts about fascinating things. I happen to know the state biologist that is the lion expert here. He told me he was out tracking a young adult female that he had radio collared several months prior. He was on foot and walked up on a ridge because he was fairly certain the cat would be below him. When he got on top he could see a small group of cow elk below. They were mature elk but not enormous. He did not see a cat though..... until it decided to go for the kill. He watched a 90 lb female cat take down a 500 lb cow elk. And it did it just how you described, from behind and by going for the back of the neck. Once it was on the elk, it quickly swung around the front of the animal's neck and clamped down on the throat. It suffocated within a few minutes.
As with nearly all cats, they are essentially woodland ninjas and can be kind of spooky. Chances are far more people have been observed by lions than ever realize it. There in lies the problem. There's two situations that come to mind in regards to defense.
A close friend of mine who does the same type of woods work I used to do all the time ran into a cat while on foot in Montana. They surprised each other and the cat felt threatened. She deployed her bear spray and the cat ran off. First rule, if you are confronted by a cat in this situation, NEVER try and run, because as with all cats, if you run they have to chase. It's programmed instinct. Never turn your back on one either, because they are programmed hunters waiting for you to do so.
The second situation is if you are being stalked. Chances are you will be blind sided and have no idea the cat was there until it's on you. Fight like hell because if you become inconvenient enough, the cat may release you.
As far as a firearm choice goes, I'm comfortable with a 9mm with a 124 grain HST. The record cat killed near my town and regionally was 169 lbs so a 9mm would do the job. Though I'm still more comfortable with at least a 357, 45acp, or 10mm.
What I learned from the two I saw is this, when a cat wants to be fast, they are scarry stupid fast, and trying to get a shot off before it's on you is really unlikely. One of them I saw was scared because I passed by in my woods truck, so it took off running. It crossed what looked to be a 150 yard wide field in 6 or 7 bounds. Think about that for a second. It was gone in the tree line in an instant.
As with any animal, avoiding them is best. Dead animals buried in duff and forest debris should be avoided. They will come back to that kill. They do eat carion too so any dead animal can draw them in. They like to hide, just like your house cat, so avoid thick brush, dense saplings, and slash piles if in a logging operation areas. When you are in the woods remember to look up also. If you scare a cat some will climb a tree to hide. That happened to one of my employees his second week. The picture is pretty cool and it unnerved him a bit. Remember to check under your vehicles too if you live in the woods. My old boss had a cat come out from under his truck one morning. His dog tried to play with it like an old friend, and the cat wasn't up for it.
The reality is that more people come in contact with bears, or at least that we know of, and make more foolish decisions around them, so I feel the potential threat is higher with bears. I may be wrong and if I suddenly stop posting one day, you all will know why. I think it makes the most sense to carry a gun big enough to deal with the biggest threat and then you know your bases are covered. In the context of this thread, 10mm is fine for a cat. Bears are more debatable as we have all seen many times on THR.