This morning when we looked, the bird nest was empty so I went outside to check the ground below. I didn't find a baby bird, but I found a lot of feathers that looked as if they might have belonged to the mother (or dad) strewn in a rather large area. I don't know what could have climbed the brick wall to devour the birds, but it looks as if something happened to them.
I hope nothing else decides to build a nest in that window. It is so sad to see them disappear before they get to maturity. (You may remember that last year I just happened to look out as a chipmunk was eating one of the eggs.)
Considering the misfortune these birds are having, it is amazing we have any birds at all!