Smuttynose, one of the Isles of Shoals off Maine and New Hampshire, is a major summer mating and nesting place for the herring gull and the great black-backed gull. Scott and Sweet, with their usual command of camera and subject, follow one year's influx of the two species from their busy arrival through courtship and copulation, nest-building, and brooding--always vigilantly guarding eggs and chicks from other gulls who would eat them, and later ""hustling"" constantly for food for their demanding young. A new gull's work begins with the 24-hour project of pecking through its shell; later the herring gull must tap a particular red spot under its parent's bill, thus triggering a feeding response--or else die of starvation. There are other hazards, and throughout Scott emphasizes the birds' relentless territoriality. (One might ask for some explanation to accompany his initial offhand reference to the ""territorial imperative,"" but the concept becomes clear as the behavior is observed.) Again, Scott integrates precise information--on such matters as the gulls' rare ability to strain the salt from sea water, or the mechanics of their soaring flight--with an attractive appreciation.