When Vic and I wrote about the house wrens in our front yard two weeks ago, we weren't sure if the nest was a real one or a dummy nest. As far as we can tell, the nest is real and the female is most likely incubating eggs at this point. We don't want to look into the box to check, though, for fear of disturbing her if she is incubating.
If you remember, we mentioned that house wrens are polygynistic, meaning that the male may take more than one mate. But each female needs her own nest box for things to work out. Well, on the day that our column about wrens came out two weeks ago, a second female entered the scene. She was presumably attracted by the vigorous singing of the male.
I dashed over to Shipley Nature Center and bought their last two nesting boxes. These are actually built for bluebirds, but wrens don't know that and use them gladly. The reason I bought two is that I wanted one for the second female wren and one for any potential bluebirds that might still show up looking for a place to live. I hung one new box in the front yard near the active nest, and the other in back.