ID'ing bird nests can be a little tricky. It's pretty straightforward if you've seen the bird around the nest, but if you just open a nesting box you may not be 100% sure what you're looking at. In order to help with nest ID's I'm going to post some pictures from the more common nest box visitors. Round 1 goes to the AMAZING Eastern Bluebirds - enjoy!
Eastern Bluebirds build beautifully neat nests. In this area they generally use pine needles and they build a perfectly cup-shaped nest. If you look carefully, you'll see the wood shavings that I put at the bottom of the box.The male is constantly zooming around the box, protecting the box against the local Tree Swallows.
Generally Blue birds will lay an average of 4-6 eggs. They can have up to 3 broods in a season although 1-2 are most common. Normally my Blue birds will start early and raise two broods. They don't seem to reuse the same box, rather they'll move to another one.