...by accident.On the day I thought my bluebirds fledged the box, I checked in to make sure they had actually left.
There were two Bluebird eggs still in there.
I left them in there for a couple days just to make sure they weren't new. I know bluebirds will have more than one brood, but since this was my first successful pair I didn't have too much knowledge on the subject. After a couple days I realized these eggs were not viable, and from the first brood.
I carefully removed the nest and set in in the woods not far from the nest box. I left the eggs in the nest....I have no idea why I did it that way...I just did.
Yesterday I, for some reason went to look at the nest...and I found this Brown-headed Cowbird egg in it. One of the "dead" Bluebird eggs was poked and pushed out of the nest!
Now I feel pretty good about this as last year I saw a Summer Tanager feeding a baby Cowbird and I know I may have just saved a Warbler, Tanager, Cuckoo, or other bird from this parasitic nest robber.