I know that lions can be scared away when they see humans approaching without fear, but what if they’re ambushed? How about a tiger, or a polar bear? If I manage to sneak up on one of these apex predators, and jump out, screaming, and running at it, will it run? Or will it just turn around and kill me? I guess I’m wondering if apex predators have a fight or flight reflex, and how strong it is if they do. Do they tend to resort to fighting more often if they’re the baddest tiger in the jungle vs the runt of the litter? Do they quickly assess the threat and respond accordingly, or does a flight instinct kick in and send them running?
I’d go for an “it depends” answer. If they are just out and about looking for food, most would probably run. No animal wants to risk injury and fighting with an unknown enemy carries too much risk. So, their instincts will likely make them run. However, if you do it near their den and/or young, the instinctual calculus may be very different and you could end up as an impromptu baby snack.