“Does one of their powers have to do with glass?” You already know quite a bit about them; care to speculate?
Hmm… I suppose it would make sense for it to be Shatterbird, between “shatter” and the public terror-inducing announcements of the Slaughterhouse’s presence… If she’s got a large range, she could shatter a whole lot of windows and glass lenses at once, making it quite apparent that they’re around.
Also, I suppose the “bird” part could mean that she does it with her voice. Maybe she makes a sound that carries far and shatters glass. Both things work well with the announcement thing.