Bird housing crisis!

Dutch artist Wannes Goetschalckx's "Nest (Home Part 2)," on display here at Amsterdam's Galerie West, is a mysterious look at our urban overcrowding problems overlaid on avian housing. I say "mysterious" because all of the birdhouses here have windows, but none of them have doors.
Comments
I think you will find that the birdhouses actually have doors, but no windows, which is usual for those style of birdhouse. What is missing is the "front step" that a bird usually lands on to enter.
It would be a great work of art to introduce to a garden and see what actually happens.
OK, birdhouses are not supposed to have doors. The bird enters the hole at the top and builds a nest in the bottom. These are perfectly normal birdhouses.