"But all we could know for sure was that these butterflies had passed through those places. Our findings didn't prove they were flying from the valleys where they spend the winters," explains Chan. To provide proof positive that they were flying from those valleys, it would be necessary to catch butterflies that had been marked at those valleys.
「但光知道蝴蝶從這些地方通過，並不能證明它們是從越冬谷飛來的，」詹家龍解釋，還必須要能在這些據點上捕獲帶有越冬谷標記的蝴蝶以「驗明正身」才行。