Monarch Butterfly Population Drops by 30 Percent in California

Published on February 7, 2024

The population of western monarch butterflies in California has dropped by 30 percent since 2022, according to the most recent count conducted by the Xerces Society. The count, done at 256 sites across the western United States from Nov. 11 through Dec. 3, 2023, shows about 233,400 western monarch butterflies stayed at sites along the California coast during the winter—about 102,000 fewer than the year before. The 2023 population is only 5 percent of its size in the 1980s, according to the study published Jan. 30. The dwindling monarch butterfly population is representative of declines of other at-risk butterflies, bees, moths, and beetles in North America, according to Isis Howard, an endangered species conservation biologist with the Xerces Society....