関連ワード:
what is the only bird that cannot fly only bird that can't fly what is the only bird that can fly backwards what is the only bird that can fly backwards and upside down what is the only bird that can fly upside down what is the only bird that can fly what is the only bird that can fly continuously for years without landing what is the only bird that can fly back what is the only bird that can fly backwards for any length of time which is the only bird that can fly backwards for a reasonable distance
