Monarch butterfly classified as a threatened species

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The monarch butterfly has taken another step closer to extinction and scientists on Thursday listed the iconic orange-and-black-winged insect as a threatened species due to its rapidly declining numbers.

“It’s a heartbreaking decline,” said Stuart Pimm, an ecologist at Duke University who is not involved in the ranking. “It is one of the most recognizable butterflies in the world.”

The International Union for Conservation of Nature included the monarch for the first time on its “red list” and classified it as an “endangered” species, two steps away from extinction.

The IUCN estimates that the monarch population in North America has declined between 22% and 72% in the last 10 years, depending on the measurement method used.

“What we’re concerned about is the rate of decline,” said Nick Haddad, a biologist at Michigan State University. “It’s very easy to imagine how quickly this butterfly could be in even greater danger.”

Haddad, who was not directly involved in the classification, estimates that the monarch population he studied in the eastern United States has fallen 85% to 95% since the 1990s.

In North America, millions of monarchs make the longest migration of any insect species known to science.

After spending the boreal winter in the mountains of central Mexico, the butterflies migrate north, reproducing in several generations over thousands of kilometers (miles). Descendants arriving in southern Canada begin the migration back to Mexico at the end of the boreal summer.

“It’s a truly awe-inspiring sight,” said Anna Walker, a conservation biologist with the New Mexico BioPark Society, who was involved in the new classification.

A smaller group spends winters on the California coast, then disperses in spring and summer in several states west of the Rockies. The decline in this population has been even more precipitous than that of eastern monarchs, although there was a small rebound last winter.

Emma Pelton of the NGO Xerces Society, which monitors western monarchs, said they are threatened by habitat loss and increased use of herbicides and pesticides in agriculture, as well as climate change.

People can help, for example, by planting milkweed, also called milkweed, a plant that caterpillars depend on.

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