User blog comment:Trainsparency/2019 Spook and Sinister Hunting Thread/@comment-40084747-20191009211801/@comment-43990775-20191009234322

they spawn anywhere besides safari roads, underwater, and underground

they are more "common" in places where they have more space to choose from of where to spawn

Ex: even though they can spawn IN the swamp, they will most likley "choose" the cliffs by the swamp because they have more space there.