讀後心得

This year, the monarch butterflies migrating from the south to the north arrived early, but in smaller numbers, with a cumulative total of 160,000, which is below the historical average of 220,000. On March 4th and on the 12th and 13th, records for the number of butterflies crossing were broken, exceeding 250 per minute, but the numbers have since significantly decreased. Conservation associations continue to monitor the situation, as some butterflies from the south are still in transit. Climate change may be affecting the migration patterns, and there have not yet been large numbers of monarch butterflies observed at the Zhunan monitoring point.

Although the speed of the migrating Danaus plexippus butterflies from the south to the north this year is earlier, the number is relatively low. It is understood that last year's record of the northward migration of Danaus plexippus reached a cumulative total of 400,000 butterflies. This year, with anticipation, the advance party arrived in Linnei Township, Yunlin County, in early March, with the number exceeding 250 butterflies per minute for two consecutive days, setting the record for the earliest road closure in history. However, after those two days, the numbers have only reached that standard twice, and the current cumulative migration amount stands at 160,000, still below the historical average of 220,000.

Since 2007, the Ministry of Transportation and Communications’ Highway Bureau has implemented the "National Highway Butterfly Crossing" measure during the migration period of Danaus plexippus, closing the outer lanes from kilometer 251 to kilometer 253 of National Highway 3 when the migration reaches 250 butterflies per minute, in order to reduce traffic harm to the butterflies. The Taiwan Danaus plexippus Conservation Association has been monitoring the culvert at the Linnei section of National Highway 3 since March, recording 210 butterflies crossing per minute on March 4. Subsequently, on the 12th and 13th, the number exceeded 250 butterflies per minute for two consecutive days, creating the earliest road closure record; however, the following observed numbers have significantly decreased, making this year one with the least road closure days.

Based on past experiences, Danaus plexippus typically leaves Linnei Township before the Qingming Festival. The Taiwan Danaus plexippus Conservation Association observed more than 300,000 butterflies in 2023 and more than 400,000 in 2024. However, this year, after the Qingming Festival, only 160,000 butterflies have migrated, which does not meet the historical average of over 220,000. The association's chairman pointed out that in the southern butterfly valley, some Danaus plexippus only began to depart on the 4th, but in small numbers. So far, the total migration count is over 160,000, and further observation is needed. Until April 30, seven volunteers will continue to monitor, count butterflies, and tag them daily.

In addition, the chairman also mentioned that the sudden temperature changes before this year's Qingming Festival may have caused some Danaus plexippus to choose to stay in the south. On sunny days, the monitoring point in Zhunan has not yet recorded large numbers of Danaus plexippus, and observations will continue this week.