Starting in Maolin, they fly their way through the valleys and mountains up through Chiayi, Taichung, and Hsinchu, all the way up North to Yangmingshan. The sheer amount of these butterflies migrating can and sometimes does stop traffic along highways in Taiwan, forcing you to stop and "smell the roses" – or, rather, watch the butterflies!
Since they are from a tropical climate, these butterflies cannot survive cold winters, which is why they migrate south in the Fall and north in the Spring. So, it helps that Taiwan’s environment in its different regions is so diverse!
Fun Fact: Purple Crow caterpillars can eat the leaves of poisonous plants. Storing the poison in its body helps defend the butterflies from predators when they are adults!
Although these butterflies are not endangered, they are under threat. In the past couple of decades, many butterfly valleys around Taiwan have disappeared due to human activities in the area. Weather patterns and vegetation have also affected migratory patterns; When Taiwan experienced a severe drought last year, this impacted both the location and timing of the butterflies’ Spring migration north, delaying it by almost half a month. To address human impact, the butterflies and their valleys are now protected, and efforts have been made to limit future impact with greater conservation efforts and partial road closures during their migration. However, with climate change and global warming affecting overall migration patterns, the “Purple Butterfly Vally” phenomena may one day disappear altogether.
