関連ワード:  why do birds fly in av shape during migration    why do the birds fly in av shape during their evening migrations    why do birds fly in av shape when they migrate to warmer places    why do migratory birds fly in a v shape    why do.birds fly in a v    why do birds fly in a v pattern    why do birds migrate in a v shape    why do birds fly in a v shape  
結果 : why do birds fly in av shape during migration