Monarch Butterflies Return to California in Large Numbers After Last Year's Historic Low

California is seeing the return of colorful friends after a record-low population last year.

Orange-and-black Western monarch butterflies are making a comeback to the area. An unofficial count of the population of these butterflies currently shows that over 50,000 monarchs are resting on the central coast. This number is in stark contrast to the under 2,000 monarchs recorded in 2020. The official count of the butterfly population began on November 13.

"This is certainly not a recovery," said Sarina Jepsen of the Xerces Society for Invertebrate Conservation, "but we're really optimistic and just really glad that there are monarchs here and that gives us a bit of time to work toward recovery of the Western monarch migration."

As reported by the Associated Press, monarchs from the West migrate to around 100 wintering sites along the Pacific coast in California. They often arrive in the state at the beginning of November and fly across the country once March's warmer weather rolls around.

A preliminary count showed more than 13,000 monarchs arrive in Monterey County, which is home to the town of Pacific Grove. The town is known for its commitment to preserving monarch butterflies, granting it the nickname of 'Butterfly Town, USA.'

"I don't recall having such a bad year before and I thought they were done," recalled Moe Ammar of the Pacific Grove Chamber of Commerce. "They were gone. They're not going to ever come back and sure enough, this year, boom, they landed."

Scientists speculate that the decline of monarchs can be attributed to climate change. The presence of the butterflies usually indicates that an ecosystem is healthy, but plants that the butterflies get their food from have been dying.

The monarch butterfly currently does not have any regulations or protections assigned to it.

For more reporting from the Associated Press, see below.

San Fran Monarch
A Monarch butterfly lands on a flower at the Rinconada Community Garden on November 03, 2021 in Palo Alto, California. Large populations of Monarch butterflies are being seen breeding for the first time in the urban San Francisco Bay peninsula. Photo by Justin Sullivan/Getty Images

The Xerces Society count from 2020 recorded fewer than 2,000 butterflies, a massive decline from the tens of thousands tallied in recent years and the millions that clustered in trees from Northern California's Mendocino County to Baja California, Mexico in the south in the 1980s. Now, their roosting sites are concentrated mostly on California's central coast.

Western monarch butterflies head south from the Pacific Northwest to California each winter, returning to the same places and even the same trees, where they cluster to keep warm.

Pacific Grove is 70 miles (112 kilometers) south of San Francisco.

Monarchs have begun clustering together on pine, cypress and eucalyptus trees and sparking hope among the grove's volunteers and visitors that the struggling insects can bounce back.

Scientists don't know why the population increased this year but Jepsen said it is likely a combination of factors, including better conditions on their breeding grounds.

"Climatic factors could have influenced the population. We could have gotten an influx of monarchs from the eastern U.S., which occasionally can happen, but it's not known for sure why the population is what it is this year," she said.

Eastern monarch butterflies travel from southern Canada and the northeastern United States across thousands of miles to spend the winter in central Mexico. Scientists estimate the monarch population in the eastern U.S. has fallen about 80% since the mid-1990s, but the drop-off in the Western U.S. has been even steeper.

The Western monarch butterfly population has declined by more than 99% from the millions that overwintered in California in the 1980s because of the destruction of their milkweed habitat along their migratory route as housing expands into their territory and use of pesticides and herbicides increases.

"California has been in a drought for several years now, and they need nectar sources in order to be able to fill their bellies and be active and survive," said Stephanie Turcotte Edenholm, a Pacific Grove Natural History Museum docent who offers guided tours of the sanctuary. "If we don't have nectar sources and we don't have the water that's providing that, then that is an issue."

Pacific Grove
Leslee Russell of Livermore, Calif. takes a picture of her husband Dave Russell in front of a mural outside the Butterfly Grove Inn near the Monarch Grove Sanctuary in Pacific Grove, Calif., Wednesday, Nov. 10, 2021. The number of Western monarch butterflies wintering along California's central coast is bouncing back after the population reached an all-time low last year. AP Photo/Nic Coury