A Monarch butterfly is viewed in a forest of eucalyptus trees at the Goleta Butterfly Preserve on February 10, 2015, in Goleta, California. | George Rose/Getty Images

The Number of Monarch Butterflies in Western North America Is Plummeting

Millions of monarch butterflies once inhabited the West Coast, but the number may now be just 300,000, highlighting the need for Endangered Species Act protections.

A new study finds monarch butterfly populations from western North America have declined far more dramatically than was previously known and face a greater risk of extinction than eastern monarchs. | Candace Fallon
A monarch butterfly on a milkweed plant | US Fish and Wildlife Service