I’m fairly certain these birds are somehow desecrate of Houdini. Wrens gain their independence quickly, and they use that independence to be the best escape artists in the bird rehab world. They escape often, and once they’re out, I believe they gain access to the bird equivalent of the cat dimension. You’ll catch the fluttering of wings in the corner of your eye, but by the time you turn your head, it’s gone. They’ll be out for hours or even days at a time, surviving on the plentiful mealworms, roaches, and spiders native to the facility. Occasionally it gets to the point where we leave doors open hoping they’ll happen to fly out. They’ll be great from hiding from predators in the wild at least.