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Monarch butterflies now listed as endangered

Monarch butterflies now listed as "endangered" in North America
Monarch butterflies now listed as "endangered" in North America 00:19

Monarch butterflies are now listed as endangered because of fast dwindling populations in North America. 

The International Union for the Conservation of Nature announced the designation on Thursday for the orange-and-black butterflies. The group estimates that populations have declined between 22% and 72% over a decade. 

After wintering in central Mexico, the butterflies migrate north to Canada. They breed new generations along the way that begin the return trip at the end of summer. 

The butterflies are imperiled by loss of habitat and increased use of herbicides and pesticides for agriculture, as well as climate change.

"Drought limits the growth of milkweed and increases the frequency of catastrophic wildfires, temperature extremes trigger earlier migrations before milkweed is available, while severe weather has killed millions of butterflies," the IUCN said in a statement.

Monarchs are seen in Massachusetts from mid-summer through early fall, according to the National Park Service.

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