the bird basically snatched them and took them into a cave where it's actual nest was at. Now there trying to figure out how to get out. They aren't able to get out without the bird's permission and even if they tried to without it they can't cause there's a barrier not allowing them to get out. Every few minutes or so (I think) there able to go more further out inside the cave to explore like for food which is what was said in this chapter, but if they go too far away they'll both end up at the start without getting anything.