Based on the research of Chan Chia-lung and others connected to the Butterfly Conservation Society of Taiwan, and on Internet views of the purple milkweed butterflies in Maolin's valleys, in his 2003 book Butterflies British lepidopterist Dick Vane-Wright listed Taiwan's purple butterfly valleys as one of the world's two great groups of wintering butterfly valleys, alongside the monarch butterfly valleys of Mexico.
2003 年 6 月，著名蝴蝶學者 Dick Vane Wright 透過台灣蝴蝶保育學會研究員詹家龍等人的研究，並在網路目睹茂林的紫蝶幽谷景觀，於是在該館出版的《蝴蝶》一書中，將台灣的「紫蝶幽谷」和墨西哥「帝王斑蝶谷」並列為世界上兩大「越冬型蝴蝶谷」。