Western monarch butterflies(WMBs, 西部帝王蝶) fly thousands of miles every year, flying north in spring and summer, and south in fall. Now, scientists want people in the western US to give them a hand by sending in any pictures of monarchs they take this spring.
WMBs, like most butterflies, help plants create seeds, which can then create more plants by spreading a dust called pollen between plants. In turn, monarchs depend on plants. They gather sweet nectar (花蜜) from flowers for food. They rest and spend their winters in trees. And they depend completely on a plant called milkweed to lay their eggs.
Their number has been dropping sharply since the 1980s, when 3 million to 10 million butterflies migrated (迁徙) annually from the northwestern United States to spend the winter at hundreds of sites along the California coast. In 2020, less than 2, 000 monarchs were counted in the entire state. But in 2021, that number jumped to 247, 237. Scientists still don't fully understand this phenomenon. But they're studying it, saying it'll take years of tracking them to work it out.
Scientists have learned a lot about where Western monarchs spend the winters. But they know much less about where they go when they leave their winter homes. That's why scientists from several universities are organizing a project called "Western Monarch Mystery Challenge" to seek for practical assistance from "citizen scientists" in the American west.
They're asking anyone who sees a monarch butterfly outside of their winter homes this spring to take a picture and send it to them. By collecting the pictures, along with the date and place where the pictures were taken, scientists hope to learn more about what happens to the butterflies and where they are after they leave their winter homes and protect them better in the future.
Last year's increase in monarch number is great news. But the number of monarchs is still way below the millions of butterflies that migrated in the 1980s.