Earth Protect Blog

By Livia Albeck-Ripka

© The New York Times Co.

PACIFIC GROVE, CALIF. » On a recent Sunday, I found myself among a crowd of hushed humans in a eucalyptus grove near Monterey, our necks craned toward the tree canopy.

Above us, thousands of Western monarch butterflies were clustered on branches, camouflaged by wings that appear dull when closed. But every so often, a group would rouse and burst into a dance of orange confetti.

One family mused on the inner lives of the butterflies. A couple watched in awe, silent. Another man called a friend by video to share the magic. He told him of how they just “flutter through.”

Monarch butterflies make among the most impressive migrations of any species, flying hundreds of miles from various parts of the United States to Mexico and coastal California, where the Western population overwinters. But in the past several decades, their populations have plummeted because of global warming, development and farming practices, leading scientists to fear that the migratory population could ultimately become extinct.

“Monarchs are a harbinger of what’s going on with many species,” said Karen Oberhauser, a conservation biologist at the University of Wisconsin. She has studied the monarchs for more than 35 years.

This year, however, the butterflies’ Western population has made a modest recovery, surprising scientists. Across California’s coast, onlookers have gathered at groves to witness the phenomenon. Amid dire news about climate change and after close to two years of pandemic life, the butterflies’ arrival has offered a reprieve.

“It’s like an escape,” Chris Messer, 30, said as he gazed up at the insects. “You get to see the brilliance of this orange dance in the sky.”

Clara Howley, who had traveled 170 miles from Santa Rosa to see the butterflies with her sister, said she was spellbound.

“We get so wrapped up in our lives. It’s nice to see the monarchs still wrapped up in theirs,” she said. “I just can’t look away.”

It is a marvel. The Western monarchs, each weighing less than a paper clip, embark on their athletic feat from west of the Rocky Mountains. Much of how they migrate is still a mystery, but scientists believe they most likely rely on environmental cues, including sunlight and temperature. Several generations of butterflies are born and die before the journey is complete.

But why are they rebounding? That, experts say, remains unclear.

It could simply be that the butterflies had an especially good breeding season (insects can reproduce rapidly, and their populations do tend to fluctuate) or that especially warm fall weather last year changed the butterflies’ breeding and migration behavior, throwing off the count.

The current numbers, however, are still a far cry from previous population totals: In the 1980s, millions of monarchs flocked to California for the winter. In 2017, an annual count found about 200,000 butterflies. Last year, the same count found fewer than 2,000.

“I was really saddened,” Oberhauser said, adding that she had worried “we might be seeing the end of an incredible migratory phenomenon.”

But the rebound, she and others say, is cause for cautious optimism. This year, volunteers have already counted more than 100,000 butterflies, according to the Xerces Society for Invertebrate Conservation.

“It’s close to miraculous,” said Paul Meredith, 77, a volunteer with the butterfly sanctuary, who that Sunday was seated — binoculars around his neck, insect pin in his cap — among the trees.

But, he added, “there’s a lot of things we don’t understand.”