I sat for about 90 minutes watching one of my nest boxes this morning. When I first got there, it appeared that a pair of bluebirds were taking things out of the house, then they began bringing in more materials to build their nest. A pair of nuthatches stopped by to check out the nest box, along with a chickadee. . Then 3 brown headed cowbirds swooped in to check things out. When I finally left, the bluebirds where still working on the nest, undeterred by all of their visitors. I'm hoping for some better photos in the coming weeks. These are all pretty heavy crops. You can really notice how the quality of the light changed throughout the morning too.