When the female is incubating her eggs, she gets "time off" every two to three hours to find food and water. If she does not return within about 15 minutes, the male bird starts up a constant "wu-wu-" that grows ever more rapid and urgent. On hearing her husband's call, the female is sure to hurry home.
當鳥媽媽抱蛋，每隔二、三小時出門「放風」去覓食、喝水，約莫一刻鐘後不見返回，公鳥就會「wu-wu--」叫個不停，越叫越急促，聽到老公召喚，母鳥也會速速趕回。