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, according to a new study in the journal Biological Conservation.
“Western monarchs are faring worse than their eastern counterparts,” said Cheryl Schultz, an associate professor at Washington State University Vancouver and lead author of the study. “In the 1980s, 10 million monarchs spent the winter in coastal California. Today there are barely 300,000.”