On a May morning, a brilliant sun shines down on a Connecticut shoreline. Flocks of shorebirds, some of them state or federally threatened, swoop onto deserted beaches with few visible signs that humans were ever part of the picture. To the north, a salt marsh punctuated by the white dots of great egrets fishing in the tidal flats sustains the illusion of a place people somehow missed.Welcome to Pleasure Beach, 77 acres at the tip of a small peninsula that boasts one-fifth of Connecticut's undeveloped barrier beaches. The controversy surrounding this tiny slice of nature underscores the daunting political challenge of reconciling human interests with those of threatened and endangered species.This place's complicated geography poses unique challenges. The peninsula is shaped roughly like a tall witch's hat lying on its side. A narrow channel that you could easily swim across separates the brim from Bridgeport's mainland. The top three-quarters of the hat is Long Beach West, little...