birds in my backyard

I have a cardinal nesting in my backyard in a climbing hydrangea vine. I noticed the nest because there was a pale blue egg with lots of brown speckles on the ground. It had a small hole in it (the size of a wren's beak) and was empty. I looked above and found the female cardinal sitting on her nest. Since I found the nest (last week), she has been faithfully sitting - so I think she has laid more eggs.

There is also a pair of wrens are in a bird house by the garden in my side yard. The female wren is spending a lot of time in the house, so I assume she has eggs or chicks even by now. The male sings to her often.

The sparrows in the back bird house had peeping chicks that I heard last week, but I think something may have happened to them (wren?). The parents are still tending house though, so either the kids are just quiet or they have a new brood on the way.

I have seen a catbird and robin in the yard often and I keep watching to see where their nests are. How many bird nests can fit in one tiny yard? I think they have nests up in the neighboring trees though and just come to my yard for water.

I did see a bluish warbler the other day in my waterfall and got a photo (below). Maybe someone can tell me what type of bird this was.