The Purple Crow Butterfly, alongside the Monarch Butterfly of Mexico, stands as one of the world’s two major overwintering butterfly species. In southern Taiwan, the valleys where these butterflies winter are primarily found from south of Chiayi to the northern low-altitude mountains of Pingtung.
In recent years, Kenting has observed an increase in butterflies being killed on roads during their spring migration, with incidents in June even seeing tens of thousands of butterflies crossing roads en masse. After a two-year study by butterfly scholar Chia-Lung Chan 詹家龍 , it’s been discovered that the protected forests of Kenting have become a new habitat for these butterflies.
Butterfly scholar Chia-Lung Chan 詹家龍
The Kenting National Park Management Office, aiming to protect this “purple ecological treasure,” plans to set up nets at migration hotspots and install speed reduction warning signs next year, turning it into a conservation highlight following bird watching and crab protection initiatives.
The Purple Crow Butterfly is one of the most populous butterfly species in Taiwan. Historically, overwintering valleys were distributed in low-altitude mountains south of the Tropic of Cancer, but due to human development destroying their habitats, valleys with thousands of butterflies have dwindled to single digits.
However, in the more southern Kenting National Park, where overwintering groups were only sparsely found in the past with an estimated thousand individuals, significant numbers have been spotted in recent years on the stretch from Kenting to Nanwan on Provincial Highway 26, as well as on the Pingtung County Road 200 from Hengchun to Manzhou.
This year witnessed a massive surge in numbers, prompting the Kenting Management Office to commission Chia-Lung Chan to investigate the butterflies’ migratory behavior and ecology within the park.
There are four common species of Purple Crow Butterflies in Taiwan, not varying much in size, with a wingspan of about 6 to 8 centimeters, classifying them as medium-sized butterflies. They are distinguished by their purple front wing backs, which reflect dreamy colors at different angles due to the scales on their wings and sunlight refraction.
Chan’s investigation indicates that Kenting’s winter temperatures are higher than traditional overwintering habitats, and the strong “downslope winds” of the Hengchun Peninsula during winter were thought to be unfavorable for the butterflies to winter and breed. Yet, it’s been found that the protected flatland forests in Kenting have become a new habitat.
“Butterflies are a moving landscape in nature!” According to Chan, the mass gathering of Purple Crow Butterflies in winter forms spectacular overwintering valleys. However, because their breeding and habitats are mainly in flatlands and low-altitude mountains, which are often destroyed by human development, Kenting remains protected. Current surveys have identified five breeding hotspots, with the Nanwan area within the Nuclear Power Plant III being the largest breeding ground for the Lesser Purple Crow Butterfly.
The peak of the butterfly migration begins in May and reaches its zenith in June. Due to the speed of the butterflies, about 20 kilometers per hour, and the driving speed limit of 40 kilometers per hour in the area, implementing “road closures for butterfly protection” during the peak migration period would have a significant impact.
Plans for next year include installing 5-meter-high protective nets alongside hotspots on Provincial Highway 26 in the Nanwan section and setting up speed reduction warning signs to remind road users to slow down, further developing Kenting’s conservation highlights after bird watching and crab protection.