Wren Nest, Redux

Are Carolina Wrens opportunistic slobs? My friend "Woodduck" wrote today to share with me a quick note about one nest they made---in a backpack, no less. And it was a mess. Probably like the very one that seems to be getting worked on here. Now look at this thing, would you? Wrens are clearly unconcerned with any amount of tidiness in their nest affairs. They'll use any material. There's even a feather in there. Not to mention hay, moss, cedar needles, and even squirrel hair. But it works for them. Maybe it's a development that evolved to avoid detection by predatours: this doesn't look like anything so why poke around in it? Or maybe it's warm and toasty for the nestlings. And I hope this one works for them, too. I'll enjoy seeing the little devils come into the world.