There are two species of winter migrating butterflies in the world, the Mexican Monarch Butterflies and the Taiwanese Purple Crow Butterflies (Euploea tulliolus). The Mexican Monarchs stay within temperate climate gorges, living in mountainous areas 3000 meters above sea level, unreachable even by cars. Because of the low temperature, they usually cluster in tight packs on trees and are rarely active. Most often it is a silent admiration of them.
In contrast, Taiwan’s Purple Crow Butterflies are subtropical butterflies, and live within gorges that are located less than 500 meters above sea level. As long as the weather is right, rainless and sunny, they are active from morning to night every day. They follow their “Three No’s Policy” strictly: No checking in, No being late, and no taking leave. Thus, in contrast, the viewing of Taiwan’s Purple Crow Butterflies is relatively easier, more rewarding and very interesting.
Maolin's Purple Butterfly Valley is a very rare and special place in the natural world – a winter home for butterflies that migrate from colder areas every year. In Butterfly Valley, one might see hundreds of thousands of butterflies: Dwarf Crows, as well as Striped Blue Crows, double-branded Black Crows, Chocolate Tigers and six or more other species.
The first flocks of butterflies arrive around November, and gradually increase in number. After February the numbers gradually dwindle as some will die from courtship and mating, or some others will migrate. Thus, the peak of the butterfly season is from December to February, which also corresponds to the local Chinese date harvest period. Visitors can arrange for a tour that includes both butterfly watching and experiencing the Chinese date harvest!
The most ideal situation is the day after a rainfall, when the sun is shining brightly. If visitors are lucky, and the time and place are all perfect, masses of Purple Crow Butterflies can be seen gliding down through the gorge, preparing to feed, drink, and sunbathe. As visitors watch their elegant appearance as they search for flowers and drinking nectar, it becomes clear why people refer to these butterflies as the dancers of nature. Obviously, it will take some luck to be able to see all of this in one day!
Organisms choose where they dwell. They choose the climate, the temperature, the humidity, and indicators of forest health. Their choices change with the environment, and thus each and every forage or tree represents a butterfly; we cannot and should not disturb the environment.
The best place to admire Purple Crow Butterflies is the Butterfly Walkway and Ecological Park designed by the Maolin District Office. The Maolin Administration has also laid out a self-guided pathway, with narrative signboards to serve as guides.
Along the roads there are also road signs to remind drivers to “Slow Down. Butterflies Ahead.” Maolin National Scenic Area is the only place in the world where traffic signs have been set up for butterflies!