California’s monarch butterfly population has declined by 99% since the 1980s

Noel Kirkpatrick

 The western population of monarch butterflies had particularly bad years in 2018 and 2019. (Photo: Bill Kennedy/Shutterstock)

Each year since 1997, the Xerces Society for Invertebrate Conservation has conducted the Western Monarch Thanksgiving Count, an annual event in which citizen scientists count the monarch butterflies overwintering in California.

The most recent results — collected in November 2019 and released this month — are not good. Volunteers reported 29,418 monarchs, according to the Xerces Society, which is just barely above last year’s all-time low of 28,429. Like last year, it’s also less than 1% of the millions of monarchs that wintered in California as recently as the 1980s, indicating the western monarch butterfly population “remains at a critical level.”…