Catastrophic Decline of the Western Monarch

Dan Western View

Monarchs cluster in the eucalyptus trees at the Natural Bridges State Park. Santa Cruz, California.

The Monarch Butterfly is an important native of the American West. Not only is it one of the most colorful creatures on the planet, it is amazingly resilient.  Yet it is delicate with membrane wings that seem so fragile, but it can fly hundreds, even thousands of miles across brutal deserts and high mountains.

Monarch Butterfly (Danaus plexippus).
Monarch Butterflies cluster together on the pines and eucalyptus trees during their migration to overwinter in Monarch Grove Sanctuary, Pacific Grove, CA.

Yet, as tough as it is, the Western Monarch is in a tragic decline.   in the 1980s, there were 4 and a half million Western Monarchs.  But the 2018 winter count was alarming.  They found only 28,000 in their winter home – a 99 per cent decline.

There are two varieties of Monarchs.  The Western Monarch winters on the California coast then spends summer in the Rockies.  It’s a long trip, but the Eastern Monarch goes even further, from Mexico to Canada.   The Eastern Monarch also has seen a significant decline, but not nearly as much as the Western.

Monarch butterflies winter home, Pacific Grove CA

These tough little creatures are facing many threats to their survival.  A major one is habitat loss.  They need flowers for nectar and Milkweed for their young.  The Monarch caterpillar only eats Milkweed, but to people, milkweed is an obnoxious plant and has not been welcome anywhere.  We just didn’t realize it was a vital food for the Monarch, and we’ve done too good of a job eliminating it.

As we began to understand the problem, several groups went to work on solutions.  The US Fish and Wildlife Service created citizen scientist programs which helps volunteers monitor the health of the species.  Milkweed gardens have been created on public land, and nonprofit groups have been created to assist with the effort.

Monarch butterflies winter home, Pacific Grove CA

These steps have made an impact but it hasn’t been enough.  The Western Monarch needs more habitat.   Everyone can help, with even a small patch of milkweed plus plants with colorful flowers from early spring to late summer, to feed them when they are migrating through our farmlands on their way to Colorado.

The majestic monarch doesn’t need to disappear from our magnificent landscape.

For more information, The Xerces Society has published a call to action. (.pdf)

Catastrophic Decline of the Western Monarch

I’m Len Wilcox and that’s the Western View from AgNet West and Citrus Industry Magazine.  Visit us on the web at

About the Author

Len Wilcox

Len Wilcox is a retired scientist who also ran a newspaper and has written for agricultural publications since the 1980s. He was a regular contributor to California Farmer Magazine. His commentary “The Western View” is a regular feature on Farm City Newsday and AgNet West.