Science

California’s monarch butterfly faces extinction as numbers plunge from millions to thousands 

The number of monarch butterflies wintering on the California coast has plummeted to a record low, according to entomologists.

Fewer than 2,000 monarchs were recorded in November and December, compared to 200,000 barely three years ago.

In the 1980s, the monarch butterflies migrating south to groves from Marin County to San Diego was estimated at 4.5 million.

By 1997, when volunteer counts began, that number dwindled to about 1.2 million.

The overwintering population plummeted from 200,000 in 2017 to less than 30,000 in 2018, representing a single year decline of 86 percent.

Climate change, habitat destruction and pesticides have all helped pushed the iconic orange-and-black butterfly to the brink of extinction, experts say.

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Fewer than 2,000 monarch butterflies were recorded in coastal California in November and December, compared to 200,000 barely three years ago

Starting in early November, western monarchs fly thousands of mile from the Pacific Northwest to central and southern California—returning to the same site, and often even the same tree, to ride out the winter.

No individual butterfly completes the entire cycle, though: Females lay eggs on the return trip north and it can take up to five generations to complete the trek back to Canada.

Since 1997, groups of butterflies, known as flutters, have been tallied every fall by the nonprofit Xerces Society as part of the Western Monarch Thanksgiving Count.

Between November 14 and December 6, 2020, volunteers surveying tree groves on the California and Northern Baja coast counted just 1,194 insects at 246 sites.

The Xerces Society, which began volunteer counts of monarch populations in 1997, has charted the insect's devastating decline

The Xerces Society, which began volunteer counts of monarch populations in 1997, has charted the insect’s devastating decline

Scientists at Washington State University predicted once the western monarch population dipped below 30,000, their numbers would drop even more precipitously. That threshold was crossed in 2019. The following year the monarch experienced a 93 percent drop

Scientists at Washington State University predicted once the western monarch population dipped below 30,000, their numbers would drop even more precipitously. That threshold was crossed in 2019. The following year the monarch experienced a 93 percent drop

That represents the lowest number in the count’s 23-year history, and a massive 93 percent decline from the 29,000 reported in 2019.

Traditional monarch meccas like Pismo Beach and Natural Bridges reported only a few hundred butterflies, the society said.

Pacific Grove, nicknamed ‘Butterfly Town, USA’ because of the thousands of monarchs that usually gather in the Monterey pine and eucalyptus trees there, had no monarchs at all.

THE AMAZING MIGRATION OF THE MONARCH BUTTERFLY

The 3,000-mile mass migration of monarch butterflies in North America is one of the insect world’s fantastic feats.

Millions embarking on the arduous journey from as far north as Canada down into Mexico and the California coast each autumn.

Monarch butterflies migrate from Canada to Mexico and the California coast every year in what's been described as one of the most spectacular natural phenomena in the world

Monarch butterflies migrate from Canada to Mexico and the California coast every year in what’s been described as one of the most spectacular natural phenomena in the world

The number of migrating monarchs has plummeted in recentyears. 

Researchers said while an estimated one billion monarchbutterflies migrated to Mexico in 1996, that number stood atabout 35 million this past winter.

Threats to them includehabitat loss due to human activities, pesticides that killmilkweed and climate change, experts say.

Monarch butterflies living east of the Rocky Mountains spend their winters in Mexico to escape the cold weather while those west of the Rockies spend winters on the California coast before returning home in the spring. 

Scientists say their orange color tells potential predatorsthey taste awful and are toxic to eat thanks to chemicals fromthe milkweed plants that nourish them in their larval state. 

 

 

‘Their absence this year was heartbreaking for volunteers and visitors flocking to these locales hoping to catch a glimpse of the awe-inspiring clusters of monarch butterflies,’ said Sarina Jepsen, the Xerces Society’s director of endangered species.

As recently as 2017, monarch populations in the region were still in the hundreds of thousands.

But a population viability model developed by researchers at Washington State University predicted the western monarch would quickly head toward extinction once its population dipped to 30,000 butterflies.

That threshold was crossed in 2018 and 2019, the society said, and now ‘It seems that, unfortunately, this prediction was right.’

‘We may be witnessing the collapse of the western migration of monarch butterflies,’ the group added. ‘A migration of millions of monarchs reduced to two thousand in a few decades.’

In all, the numbers recorded in the 2020 count represent a 99 percent decline since the 1980s.

Monarchs have been in decline elsewhere: The eastern migratory population —which travels from southern Canada to central Mexico—has dropped 80 percent since monitoring began.

Two workers at a monarch butterfly sanctuary in Michoacán, Mexico, were murdered just days apart in 2020. Authorities haven’t announced a motive but illegal logging is common in the area, despite a ban to protect the butterflies, The Guardian reports.

In December 2020, the U.S. Fish and Wildlife Service declined to add the monarch butterfly to the Endangered Species Act, claiming it was ‘warranted but precluded by higher priority actions.’

A month earlier, a California court ruled the state didn’t have the authority to put insects on its own endangered species list.

Entomologists point to a number of human factors threatening the majestic insect, including increased pesticides, massive wildfires, the clearing out of groves for housing developments, and the loss of milkweed, the monarch caterpillar’s sole host plant.

Climate change has also disrupted the monarch’s migration patterns, researchers say, which are synched to season changes and the blossoming of wildflowers.


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