Western monarchs, the population found west of the Rockies, overwinter in groves along the Pacific coast from Northern California’s Mendocino County south to the northern edge of Baja California, as well as in a few inland locations. The Western monarch count is conducted by trained volunteers over several weeks around the Thanksgiving holiday. “And the root of those are habitat loss, both at the overwintering sites in California and elsewhere, and then migratory breeding habitat,” she said. Among details in the data, the count showed that overwintering sites trended to the south. California's central coast usually sees the most monarchs, and the San Francisco Bay Area normally has significant numbers as well.

Source: Forbes January 25, 2022 21:37 UTC