3am birding

While walking across campus today at 3am, it was absolutely silent, with no other human in sight. I was amused to list four species of birds before I made it home, though. A Robin belted out song on campus, with the echos off of buildings making it sound like a small chorus was going. A Killdeer called once, and 2 different Juncos sang once. A Song Sparrow sang a few songs, and a second Robin started up. I knew birds sang at all hours of the night, but I always thought it was the occasional isolated incident...