Nesting Wrens

We have a birdhouse hanging in the tree in the front yard (a Christmas present from Tory two years ago). Last year, something built a nest in it, but either didn't use it or used it while I was in Italy so that I didn't get to see it. Anyway, this year I had high hopes for it. I saw Chickadees and House Sparrows fighting over it early in the season. The House Sparrows apparently won (blah), but they never nested. They went in and out but never had chicks. So my hopes were dashed. Then I noticed a little House Wren in the tree. It's an aggressive little bugger. It chased a squirrel out of the tree one day. Yesterday I noticed another House Wren and saw that they were going in and out of the bird house! Hopefully they'll be able to successfully nest in there and I can see baby House Wrens. I've been trying to get some pictures, but House Wrens are so small and I don't want to scare them away. So this is all I've got.