I ask Burns whether she can sex the birds. “Only when one lays an egg,” she confides, “although the females tend to look a bit more refined than the males, with slimmer bills.” Of the 16 birds we check today, all are males except one. A couple are stragglers which bred last season and are taking their time about leaving. All are beautifully white, but their nobility of bearing is undermined by the putrid fishy smell that surrounds them.