Exciting news indigo! I can only speak from my own experience and say that I have had Chickadees nest in a BB box here, and the Blues did not try to swipe the box. Then again, I had 2 other options in the yard for the Blues. Do you have another BB box up? I'd put one up if you don't. I haven't heard of using a Sparrow Spooker on a box of Dees. Hope that someone here knows. I don't put one on mine. It's cool that you will be able to monitor the Chickadee nest. Their little eggs are the size of Jelly Belly jelly beans. Sometimes, the moms will sit tight on the nest when you open the box, even after you thump on the box before opening it. :o)

I use a spooker on my Dee box. If the Blues bother them put on a hole reducer. I think there are directions on how to make on on the sialis site. Good Luck!

I also treat the Dee box the same as the Blue's box and put up a sparrow spooker after the first egg is laid. As Bandjzmom suggested, I would also make sure there is another box for the Blues to use.