As I pointed out with the American Bittern, most herons don't sing, but
bitterns do. That's presumably because each bird occupies its own patch of marsh,
instead of flying around from one feeding spot to another, as most herons do. If so, they would
need to advertise their presence to friend and foe, just as the cohabiting rails do.
This five-note,
accelerating song, emanating from deep in the cattails, sounds perfect for the job. It even has the
same cadence as the Yellow Rail's song. It also would fit nicely on the
sound track of one of the Jurassic Park movies. With that context, it might
suggest a long-knecked biped with beady eyes. In fact, that is just what it is.