For the (urban) birds.
I thought these birdhouses were simply part of an art installation, being that they are on the High Line in New York City. Then I heard a "chirp." One google search later, I learned that the birdhouses are the work of Sarah Sze, who wanted to create an artwork that is "simultaneously an observatory, an experiment, and a metropolis, evoking urban construction, scientific models, and attempts to capture nature in situ." Translation: lucky birds.