This little male is flapping his wings to seduce the little female on the box. They're not building nests yet, but territory is being claimed, and mates selected. Last summer's fledgling Bluebirds seem to have stayed close to home, but soon they'll have to find their own territory. I wish I could have a garden full of bluebird boxes, but once mating begins they don't share well. A nest box in the back and one in the front seemed to work well last year. As long as they don't see each other they seem to coexist, but last summer, when they did occasionally meet at the bird bath, there was a little skirmish. I think another bird bath will be on the list of things to buy this summer.
