Any creature that has evolved to survive in a given environment instinctively knows how to make the best use of its particular adaptations.
That seems like a straightforward principle, doesn’t it? Yet monsters in Dungeons and Dragons campaigns often fail to follow it.
No doubt, that’s largely because many of us begin playing D&D when we’re teens (or even pre-teens) and don’t yet have much experience with how the world works. Or we come to D&D as adults with little or no background in the military, martial arts, evolutionary biology or even tactical simulation games, and so we don’t consider how relative strengths and weaknesses, the environment, and simple survival sense play into the way a creature fights, hunts or defends itself. Consequently, we think of combat as a situation in which two opponents swing/shoot/claw/bite at each other until one or the other goes down or runs away.