Monarch Butterfly Numbers Aren't Looking So Dismal

California count appears to be much higher this year
By Newser Editors and Wire Services
Posted Nov 17, 2021 7:33 AM CST
Monarch Butterfly Lovers Have Reason to Be Optimistic
A butterfly sits on a leaf at 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)

There is a ray of hope for the vanishing orange-and-black Western monarch butterflies. The number wintering along California's central coast is bouncing back after the population reached an all-time low last year. An annual winter count last year by the Xerces Society recorded fewer than 2,000 butterflies, a massive decline from the tens of thousands tallied in recent years and the millions observed in the 1980s. This year's official count started Saturday and will last three weeks, but an unofficial count by researchers and volunteers already shows there are over 50,000 monarchs at overwintering sites, said Sarina Jepsen, Director of Endangered Species at Xerces Society for Invertebrate Conservation.

"This is certainly not a recovery but we’re really optimistic," Jepsen said. 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 US, which occasionally can happen," she said. Scientists estimate the monarch population in the eastern US has fallen about 80% since the mid-1990s, but the drop-off in the Western US has been even steeper at a more than 99% decline, reports the AP.

The decrease has been attributed to the destruction of their milkweed habitat along their migratory route as housing expands into their territory and use of pesticides and herbicides increases. Researchers also have noted the effect of climate change, one of the main drivers of the monarch’s threatened extinction. "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," says one monarch sanctuary tour guide. "If we don’t have nectar sources and we don’t have the water that’s providing that, then that is an issue."

(More monarch butterflies stories.)

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