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Scientists have put the monarch butterfly on the endangered list because of its fast dwindling numbers. The population of monarch butterflies in North America has declined between 22% and 72% over 10 years, depending on the measurement method. More than 40,000 species are now threatened with extinction as scientists warn that the Earth is undergoing a sixth mass extinction event driven by human activity.

科学家已将帝王斑蝶列入濒危名单，因为它的数量正在迅速减少。北美的帝王蝶的数量在10年内下降了22%至72%，依测量方法不同而不同。现在有4万多个物种面临灭绝的威胁，科学家警告说，地球正在经历由人类活动驱动的第六次大规模灭绝事件。