Bears and tigers attacking humans, stampeding elephants, orca's attacking ships off the coast of spain. Sharks snacking on diver's, octopi with 100 ft tentacle reach feeling around on the top of boats. In fact there is one swamp in asia where the tigers can't be hunted effectively by humans and they'll snatch people out of boats. They aren't afraid of humans because humans have demonstrated themselves able to follow them back into the swamp. All of these things and more have happened in the real world. and if a pack of wolves (real world) can be smart enough to observe and decide to attack only the animals after the people leave or even are smart enough to avoid the dangerous people, give your magical monster's the same level of intelligence. If animals fought with the same tactics I see in most games , all predator animals in our world would be extinct by now.