At first acquaintance, migratory birds seem to move in a solid mass, all for one and one for all. Closer study of the North Basin this season shows it ain’t necessarily so. In the last week of April, a raft of perhaps five hundred Greater Scaup assembled in the North Basin and then all took off for their annual migration to their northern breeding grounds. Almost all, that is. A lone female Scaup stayed, or was left, behind. She remained the sole Scaup on the water for almost three weeks. Then, out of the blue, four male Scaup appeared and clustered around her. They hung together for a few days and then the whole group disappeared, presumably northward. This afternoon I saw with considerable surprise a solo Greater Scaup male hanging out loosely with a coven of five American Coots. These Coots are themselves refuseniks, or outcasts, from an earlier Coot emigration at least as massive as that of the Scaup. The five hang out in the shadows of the Opening Circle promontory on the upper east side of the park, and look like they’re settled in for the year. Is today’s bachelor Scaup one of the four Scaup who came to rescue the lone female? Or is he a different bird altogether, stopping in from somewhere farther south? How lovely it would be to be Dr. Dolittle, who spoke the language of creatures other than ourselves.