Awww! and Aaarrrggghh! I understand your conflicting feelings about this discovery. If your goal is to non-violently get them to move on to greener pastures (and out of your patio furniture!) I have an idea: Squirrels really don't care for the smell of mothballs. Just scattering them won't work because a determined momma would just push them off your deck, but if you were to fill some stockings with several handfuls, and hang the odoriferous bags full in close proximity to the nursery (maybe using those shepherds crooks that clamp on to deck rails?), you could probably get them to move on in short order. Personally, I'd have to do this because Jazmyn has proven herself able to catch adult squirrels, and Izzy would clean out the babies in a heartbeat, and I wouldn't be able to stand the sight or sound of it...

Kathy -- when I went back out, I decided that BOTH nests look like they are primarily twigs, though there certainly are some more grass-like pieces as well as a few small seedheads (maybe dried sedum?) in the second one (it's also not as deep). I pulled out the one that was clearly all twigs (had a very deep "cup" in the middle but no eggs), but I left the other because I just wasn't sure. Here are the two pictures: first is the all-twig one that I removed today (how well do I need to clean out the box? I think there are a few twigs on the floor since I didn't have a brush with me). The second is the other box. Just a note: these two boxes are fairly close together because last year we had tree swallows and I had read that tree swallows and bluebirds will "share" space if there are two boxes. Swallows won't let another swallow pair nest nearby but will leave the bluebirds if they want the other house. I think what I read (on Audubon site or somewhere) was to put the two boxes about 10-15 feet apart. I know that's not what you do if you want actual bluebirds to use them both, but we were hoping to keep a pair of bluebirds in the one if the swallows returned this year (those swallows are GORGEOUS birds, too!)

Today I found an egg in that nest! It's 2cm long (20.5 mm). According to http://www.sialis.org/eggsizes.htm it could be a Carolina wren or House sparrow. It's larger than the wren and smaller than the sparrow. While investigating, a carolina wren was screaming at me from a near by bush, and it seemed to be very upset with me for being there. It may be his nest or he could have a nest near by. I installed spooker on bluebird house that on this yard. Just in case if this is house sprarrow nest. Babies pretty big in this box. (I wrote abot 4 babies earlier, but I was wrong about quantity) I can't stay on that yard for long to make sure they accepted it because have small baby with me right now. Do you think this is a good idea or I should take it down? This is the box Janie - birds lay one egg in day, and same, as you wrote it earlier, skip a day in egg laying. She starting incubation only after she will lay her last egg. All this time eggs stay cold - up to 10 days if she skipping days and lay 5 egg. I surprised that this is new for you.

That is always an amazing sight! I saw chickadees fledging a few years ago by chance and I was hooked since then. BTW, you may want to put a metal hole reducer to 1-1/8". I have a friend whose nest box had chickadee nestlings and they were attacked by a house sparrow. She was heartbroken.