Scroll down to the Monotonic Trills...
http://www.allaboutbirds.org/guide/easte...
I'm from New England and I've got these birds in my back yard that make this noise for hours on end.I've never actually seen them but I got a video (there's not really anything to look at, it's just for the sound) and I was hoping someone might be able to tell me what they are.
