In the general Cape Cod area there are two principal nesting places every year, at Tern Island, Chatham, and in Plymouth. During the season--the birds arrive about the end of April--both terneries have populations which number in the thousands. There are in addition a few small islands off the Cape and a few comparatively isolated areas where smaller groups nest successfully, although terns are sociable birds, and breed best in large numbers. In August, beginning with the arctic tern, which, I am told, is the earliest to migrate, the birds begin to leave their nesting sites in groups or small companies on their way south. They spend the winter anywhere from Florida to the edge of the Antarctic ice. So the Paine’s Creek area, with its sand eels and alewife fry, represents a way station, a stopping-off place, one leg of a migratory journey ... the first for birds hatched during the late spring or early summer. Terns reach flying age in a month, but their parents go on feeding them for some time. They are slow to mature and do not breed until they are about three years old. The young are not much smaller than their parents, and without a close watch it might be hard to tell the difference at first; but their heads are gray, as compared with the jet-black napes and crowns on the adults. They still spend most of the time waiting to be fed. Some make inexperienced, practice flights over the water, plunging in and out in an almost kittenish, hit-or-miss way, while their parents dive like arrows, pinpointing the surface with little flashes of spray, from which they rise up with silver quarries in their sharp bills. But as many more of the young terns stand along the beach or on shoals at the mouth of the inlet, crying, begging to be fed. Terns are intensely active and brilliant in performance. They are comparatively small birds, but they are capable of migrating over thousands of miles of ocean waters, and their long, angled wings beat deep, low, and strong. They are all black and white sharpness, flashing as bright as the gold circlets of water around sharp grasses at the mouth of the inlet. They swing. They dart. They winnow the air. Their lovely white shuttlecock tails spread out and settle as they turn against the wind, crying: “Kierr! Kierr!” Two juveniles wait on a shoal, constantly calling in a high-pitched tremolo, intensified when a parent bird flies over them. The trim expert adult flies past, then swings back down the shore and circles back, finally coming in to land between them. It has no food in its bill, but stands there for a minute or so, and then begins to move away from them, as they crouch and strut after it in an almost elderly way, crying their protests. It signals departure with a slight lift of its wings and in a few seconds flies up, the thwarted young ones taking off behind it.