每日英語跟讀 Ep.K160: California Throws a Rescue Line to Its Dwindling Monarch Butterflies
Known for their windowpane wing design and bright orange color, Western monarch butterflies add a dash of magic to the California coast, where they spend the winter. Now a coalition of conservation groups, the California Department of Fish and Wildlife, and the environmentalist organization River Partners are working together to extend a lifeline to the monarchs, whose population has been dwindling drastically.
The groups have embarked on an effort to add 30,000 milkweed plants across the state to provide the butterflies with places to breed and acquire the sustenance for migration.
The Western monarchs’ California population has fallen 99% since the 1980s, The San Francisco Chronicle reported. A major factor in that drop has been a decline in milkweed caused by farming and pesticide use. Milkweed is vital to monarchs as a place to lay eggs and as a food source for their caterpillars.
Monarch butterflies do something called “overwintering” on the coast of California — spending time there from October to March before migrating farther inland to breed.
Every year around Thanksgiving, volunteers count the migrating monarchs at the coastal overwintering sites, said Cheryl Schultz, a biology professor at Washington State University who works with the River Partners project. In 2019, 29,000 butterflies overwintered in California. A year later, that number was just 2,000, she said.
In response, California put forward a $1 million state-funded initiative to restore the Western monarchs’ natural habitat — and hopefully the population itself — by planting 600 acres of milkweed statewide.
“It’s going to take time for that habit to establish,” Schultz said. “It’s not like we can plant milkweed today and poof, you know, three months from now we have 40 functioning habitats for monarchs. Different areas will take different amounts of time to come online.”
Although monarch butterflies are faced with extinction, the species is not federally protected because other species are a higher priority.
According to the U.S. Forest Service, milkweed is a wildflower known for being “a mega food market for insects.” Almost 500 types of insects, including butterflies, feed on some part of the milkweed plant — its sap, leaves and flowers all provide nutrition.
Schultz said that, aside from being a source of food, milkweed contains cardenolides, enzymes that when digested by monarch caterpillars make them toxic to predators like birds.
休茲說，除了作為食物來源，乳草還含有強心甾，這些酶被帝王斑蝶幼蟲消化後，會使幼蟲對牠們的掠食者如鳥類而言具有毒性。Source article: https://udn.com/news/story/6904/5544159