讀後心得

This year, the migration speed of the Danaus plexippus from the south to the north is earlier than usual, but the number is smaller. As of now, there are only 160,000, which is lower than the historical average of 220,000. In March, the advance team arrived early in Linnei Township, Yunlin County, setting a record for the earliest road closure in history, but there has not been a large-scale migration following that. Although there are still some Danaus plexippus departing from the butterfly valley in the south, the numbers are limited. Temperature changes may have affected their return north, and volunteers continue to monitor the situation.

This year, the migration of the Purple Butterfly from the south to the north started earlier, but the number is fewer. At the beginning of March, the advance team of the Purple Butterfly arrived early in Linnei Township, Yunlin County, and during two consecutive days, the number exceeded 250 butterflies per minute, setting the earliest record since the closure of National Highway 3. However, this number only reached the standard in those two days, and the cumulative migration count stands at only 160,000, which is below the historical average of 220,000.

Since 2007, the Ministry of Transportation and Communications' Highway Bureau has implemented the "Highway Butterfly Path" measures during the Purple Butterfly migration period on the Linnei section of National Highway 3. Whenever the migration count reaches 250 butterflies per minute, they will close the outer lanes from kilometers 251 to 253 to reduce the impact of traffic on the Purple Butterfly migration.

The Taiwan Purple Butterfly Conservation Association observed on March 4 at the culvert of the Linnei section of National Highway 3, recording a count of 210 butterflies per minute; on the 12th and 13th, it exceeded the closure standard of 250 butterflies for two consecutive days, breaking the earliest closure record in history. However, the subsequent migration number significantly decreased, making it the year with the least number on closure days.

Based on previous experiences, the Purple Butterflies typically leave Linnei Township before the Tomb-Sweeping Day. The conservation association observed over 300,000 butterflies in 2023, and it is anticipated that the number will exceed 400,000 in 2024. However, only 160,000 butterflies were counted after this year's Tomb-Sweeping Day, far below the historical average of over 220,000. The chairman of the association stated that some Purple Butterflies still left from the Butterfly Valley in the south on the 4th, but the number was not large. As of now, the cumulative migration count stands at over 160,000, and continuous observation is required, with plans to send seven volunteers to observe and tag daily before April 30.

The chairman pointed out that there were significant temperature fluctuations before this year's Tomb-Sweeping Day, which may have caused some Purple Butterflies to choose to stay in place. As for the observation point in Zhunan, no large number of Purple Butterflies have been recorded yet, and observations will continue this week.