“The sight of hundreds of thousands of butterflies with purple wings that appear to change color as they catch the sunlight at different angles is a thrill for many people,” he said.
Yet this rare migratory pattern has led to the deaths of thousands of butterflies as motorists run into them on Freeway No. 3, which lies along their migratory path. However, measures taken by the National Freeway Bureau over the past three years have resulted in a significant decline in the road-kill rate.
A study by National Taiwan University entomology professor Yang Ping-shih (楊平世) showed that the number of butterflies killed by cars declined from 3 percent of the flock in 2007 to 0.3 percent last year.
Encouraged by the progress, the bureau this year expanded the section of the freeway to be closed during the migration peak period to 3km from the previous 2km and extended a security net to 660m from 460m to encourage the butterflies to fly higher, avoiding the traffic.
“The protective measures are very special. They can only be found in Taiwan. We are proud to be spending a little money to offer some protection for the butterflies and the environment,” National Freeway Bureau Director-General Lee Thay-ming (李泰明) said.
Butterfly populations in Taiwan, which has one of the world’s highest butterfly densities, were decimated by commercial collecting, particularly in the 1960s, when they were sold by the kilogram to collectors. The practice of capturing large numbers of butterflies for commercial use is rare today, because it is no longer profitable.
Today, human encroachment remains the greatest threat to the insects.
Chan said about 200,000 butterflies disappeared as a result of the construction of a parking lot in Maolin to accommodate tourists in the 1990s.
To prevent similar problems, an area has now been marked off as a butterfly sanctuary in the Maolin National Scenic Area. It is part of a conservation program sponsored by the Council of Agriculture that includes the cultivation of plants upon which the insects feed.
“I hope the latest steps to provide the purple crows safer passage during their migration, coupled with a greater public awareness of the problems they face, can help increase butterfly populations,” Chan said.
Some conservation experts share his view, arguing that more must be done if Taiwan is to keep its reputation as a “butterfly kingdom.”
Hsu Yu-feng (徐堉峰), an entomology professor at National Taiwan Normal University, said butterfly numbers provide an important indicator of the state of the environment.
Butterfly numbers have fallen from a high of 11,500 butterflies per minute recorded during the 2005 migration period, experts said.
“A decline in the butterfly population could signal a deterioration of our environment, so we have to pay more attention to the environment and protection of butterfly habitats,” Hsu said.
Also See: Britain's disappearing butterflies
RSS