One of the best parts about moving to my hobby farm has been bird watching. Last Summer, I noticed several humming birds about the house -- a log cabin. Now, I know why. I suspect they eat larvae from carpenter bees. I will put out a welcome mat in the Spring.
I also found a nest fallen in my Yard. It's made of small twigs and what appears to be some kind of fiber. I put the small key in it to give you an idea of the size.
My wife used a stick to pick it up; looked to delicate to touch.