Wed, Apr 10, 2019 - Page 14 News List

Highway gives way to purple crow butterfly swarms
紫斑蝶年度大遷徙 國道封閉讓路

A purple crow butterfly is pictured in Kaohsiung on Jan. 2.

Photo: Huang Chia-lin, Liberty Times

The mass migration of purple crow butterflies is one of Taiwan’s most spectacular ecological events. Numbers of migrating butterflies peaked at the end of last month, with a butterfly cascade of up to 1,200 insects per minute flying over National Highway No. 3 at Yunlin’s Linnei Township. This year has seen the largest purple crow butterfly migration recorded in a decade.

The purple crow butterfly and the monarch butterfly in Central and South America are the only two known butterfly species that engage in mass migrations. In Taiwan, the purple crow butterflies’ annual mass migration occurs from the wintering valleys in Kaohsiung and Taitung northward to their birthplace in areas such as Miaoli County. The returning butterflies will pass through Yunlin County’s Linnei Township en route, and butterfly watchers can most easily see them in the foothills of the mountains. The purple crow butterfly mass migrations mostly take place around Qingming Festival, otherwise known as Tomb Sweeping Festival, so purple crow butterflies are also known locally as Qingming butterflies.

The annual migration north crosses the Jhuoshuei River. One important section along its route is Section 252 of Highway No. 3. Nets are erected along a 2km stretch of this section, so that passing butterflies are not hit by speeding vehicles. Should the rate of butterflies exceed 250 per minute, the northbound outer lane will be closed.

On March 21, volunteers from the Taiwan Purple Crow Butterfly Ecological Preservation Association captured a small purple crow butterfly with its wing marked “MT217.” It had been marked and released in Kaohsiung’s Maolin District on Feb. 17, and taken 33 days to fly the 100 km to Linnei. It is believed the butterfly is headed to Miaoli’s Jhunan Township.


1. migration n.


(qian1 xi3)

2. purple crow butterfly phr.


(zi3 ban1 die2)

3. peak v.


(da2 dao4 gao1 feng1)

4. monsoon n.

季風 (ji4 feng1)

5. honey plant phr.


(mi4 yuan2 zhi2 wu4)

The purple crow butterfly migration occurs only when certain conditions are met. Firstly, the northeasterly monsoon needs to turn to a southerly wind, allowing the butterfly to ride the airflow northward. Secondly, the weather must be dry. Thirdly, there must be honey plants along the route. The last few years have brought challenges to the purple crow butterfly mass migration. Warmer weather and low rainfall, for example, have meant that there have been fewer honey plants, and they have bloomed at irregular times.

(Translated by Lin Lee-kai, Taipei Times)







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