Rebecca,

Do you know what wren guards are? I have had SO many problems with house wrens in past years. You might consider putting one on the box when the bluebirds have laid their first egg.

My experience is that the wrens don't seem to bother empty nests (although I know that they do). They wait till there are eggs or young chicks. I've had them peck eggs and throw them out of the nest box.

The worst things I've had the house wrens do, though, is throw just-hatched chicks out of nest boxes. I've had them do that with baby bluebirds and last year just-hatched chickadees. With the bluebirds, I caught them in the act (nest box cam) and returned all chicks to the box. However, the next day they did it again! I was able to return the chicks to the box. Last year I was only able to find 5 of the 6 chickadees (I didn't know there was a chickadee nest or I would have put a guard on it). I returned those to the box and put on a wren guard and they survived.

Now I always put a wren guard on the box when the first egg is laid. You can find out more about this at

sialis.org

good luck! Linda...

As soon as the first egg has been laid, I put up a Sparrow Spooker. (Homemade from Mylar) Then I make my own wren gaurd so the wrens cannot see the hole to the Box. I need to go check the box, as I feel the first egg may be there today! I love you all!
Rebecca