This is an ingenious trap that truly works like a champ. (use cheetoes and bread for bait) I bought one because
I had a number of House Sparrows that had moved in and were killing bluebirds. (they attack adults, but their modus is attacking nests to kill chicks - they're horrible little beasts)
They are a tremendously aggressive non-native species that have done damage to native bird populations. Some would argue that they may act as disease carriers to your flock, but who knows...
(funny, as I was writing this I heard the telltale chirp outside and lo and behold, one was sitting beside a Swallow box - time to go set up Uncle Blaines sparrow trap myself!)
I set my trap up the first of the bluebird breeding season, because the males were hanging around my bluebird box. I actually caught a couple right off. Now they are back and setting up shop in my barn, making a horrible racket and munching on my chicken feed. I have the box set up again, and am getting no action at all. Im afraid Im going to somehow have to figure out how to not have chicken feed out all the time, and give them a reason to check out the trap. It does, work, tho.