A remarkably diverse population of bird life, migratory and indigenous, lives in the region known as the Chesapeake Bay country. It is one of the finest locations on the eastern seaboard for observing wild birds. Among the cattail and wild rice, the cordgrass and loblolly, from the countryside north of Baltimore to the windswept beaches of the Atlantic, are the imperiled canvasback, the boat-tailed grackle, the secretive king rail, the fragile egret,...