题型：阅读理解 题类：模拟题 难易度：普通
内蒙古赤峰市2021届高三英语3月模拟试卷
Western monarch butterflies(帝王蝶)spend their winters on the central California coast. A few months later, they produce young in the Central Valley and as far north and east as Idaho. But where they go in between remains an open question to biologists. Therefore, a group of biologists call on anyone who spots a monarch north of Santa Barbara this spring to get a quick shot(镜头)and email them the photo with a date and a location.
"Something's going on in early spring," said Cheryl Schultz, a professor at Washington State University Vancouver. "Winter survival isn't the problem in the short term, but they don't know whether the monarchs are not making it producing places, not finding plants to feed themselves along the way," she said.
The Western monarch population stood in the millions in the 1980s. In 2017, an annual count found 200,000 butterflies. In 2018, the number fell to about 30, 000-a figure that held steady last year. The monarchs' decline is part of a large trend among dozens of butterfly species in the West. What exactly caused the decline? Biologists attach it to a variety of reasons. Many chemicals are sprayed on the milkweed(乳草)monarchs will feed on. Climate change also plays a role in challenges facing monarchs. Yet, they're not nearly as threatening as those leading to loss of their living room. Farms used to have rough borders that were grounds for the plants monarchs love and live in. However, newly applied practices pushed crops to the edge of fields.
"Butterflies often have good and bad years. We do think there's potential to turn the situation around." Dr. Schultz said. And she said she saw two reasons for that. First, the population decline seen in 2017 ~ 2018 wasn't repeated last year. And second, she's seen butterfly populations recover before.
试题篮
