This one made me laugh. Just before I took it, I shot one of the female bluebird with a big mouthful of long dried grass. Dad has a tiny wisp of grass. :0)
I guess it is the same with all creatures. My friend said the same thing was happening with the finches that built on her porch. The male just brought in a token stray every now and then while the female did the bulk of work. He is handsome thought. Maybe she thinks he's worth it.