But research has determined that only four species of crow butterflies and two species of tiger butterflies that spend the winter in those Tawu valleys have clearly elevated fat levels. This shows that the other seven species of milkweed butterflies must use some unknown method to pass the winter. The next step is to research the milkweed butterflies 'breeding functions.
但研究結果卻發現，大武越冬谷中只有 4 種紫斑蝶和 2 種青斑蝶冬天的脂肪明顯高於其他季節，顯示其他 7 種斑蝶應該另有渡冬妙方；下一步還要研究斑蝶的生殖功能，說不定又會過濾掉一些。