If you have not heard an outburst at close range from a Clapper Rail, then you have not lived. You can feel it in your bones and if you are not prepared, beware that people have pooped themselves when surprised by a Clapper. The following pics are from Bombay Hook in Delaware but I also added some from NC of a swimming Clapper.
Black Rails? Just kidding. They are clearly Clapper chicks.
Here are some NC Clappers. These were taken at Cedar Island marsh.