They aren't that dumb if they can see. I used to let my big crested birds free range, but everyone with the big crests got killed by a hawk so they aren't allowed out without being watched. If you trim off their crests around their eyes they can do better. I found that my little silkies had a hard time following the larger birds at times through brush because they got their leg feathers stuck in the black berry bushes, and because they are so small, would have to walk around some stands of grass because they couldn't push over them.
It's so funny to see a silkie walk right into something it can't see and wonder what happened.