Although common in much of its range, the American Bittern is usually well-hidden in bogs, marshes and wet meadows.
Usually solitary, it walks stealthily among cattails or bullrushes. If it senses that it has been seen, the American Bittern
becomes motionless, with its bill pointed upward, causing it to blend into the reeds. It is most active at dusk.
More often heard than seen, this bittern has a call that resembles a congested pump.  Source: Wikipedia