Here is the call of the Great Blue Heron: http://www.enature.com/fieldguides/detail.asp?sortBy=has+audio&curFamilyID=219&curGroupID=1&lgfromWhere=&curPageNum=2   Step, step, step, she moves along the river bank, a careful walker. Her neck – a gray and white question mark – moves in contrapuntal rhythm to her lower body, and the whole of her is a food-seeking machine. When startled…