The Purple Martin above pokes its head out to see what’s going on below. The Purple Martin below is next to what appears to be a Northern Rough-winged Swallow (although I’m not sure about that). According to my field guide the female Purple Martin does not have that much brown in it.
Note: someone has assured me that the females can show a blue-brown and the martins wouldn’t allow a Rough-winged Swallow on their birdhouse. Therefore I now believe the brown bird with its back to us is a female Purple Martin.
Nice shot with a lovely composition! FWIW I have seen photos of Purple Martin females that look pretty brown and you can see a tiny bit of a blue tinge on the wing edges here. I can’t imagine the Martins tolerating any other species that close to the nest.