Western monarchs are not as well-known as their eastern counterparts that migrate all the way to Mexico each year. The western population of monarchs overwinter along the Pacific Coast, but it’s definitely not the only habitat they need. We wanted to share some of our favorite photos of these monarch butterflies, and the diversity of habitats (both expected and surprising) they use across the West.
Although not known for exorbitant populations of monarchs, some do spend the summer breeding season in the Pacific Northwest. This monarch is shown on showy milkweed within a restored habitat on a ranch in Corvallis, Oregon.
The deserts of southern and eastern California are home to a special kind of milkweed known as desert or rush milkweed (Asclepias subulata). Where there is milkweed, you will find monarchs! Here is a monarch chrysalis on desert milkweed in Palm Springs, California, October 2017.
Many monarchs west of the Rocky Mountains migrate to the California coast to overwinter…but not all of them….
In just the last few years, it has come to our attention that monarchs overwinter in Baja California, Mexico. Saul Riatiga has been leading overwintering counts in Baja since 2016 but prior to his involvement, there was little to no known data of the monarchs overwintering in this area.
Monarch butterflies, like many other migratory insects and animals, need places of refuge to survive during their migration journey. They even rely on habitat in Inyo Mountains Wilderness, adjacent to Death Valley National Park near the California/Nevada border. To give you an idea of why this is shocking, here’s a picture of the area:
Despite the desolate landscape, monarchs were thriving. In the West, we have observed that mulefat is a critical source of nectar during the winter for monarchs, as seen in the photo below. This monarch may have migrated to the desert valley for overwintering, or may simply be passing through. Researchers are still trying to uncover this secret.
Western monarchs are everywhere, yet we still have so much more to learn about this fascinating, declining insect. Learn more about the recently announced population numbers here.
You can help us learn more about these monarch mysteries through citizen science.
Get involved with Monarch Conservation:
- Idaho: Advocates for Idaho Monarchs Facebook Page
- Oregon: http://www.somonarchs.org
- Washington: Washington State University — Monarch butterflies in the Pacific Northwest Facebook Page
- Utah/Arizona: https://www.swmonarchs.org/
- California: https://monarchalert.calpoly.edu/ and https://www.westernmonarchcount.org/
- Western United States at large: https://www.monarchmilkweedmapper.org/ and https://mlmp.org/default.aspx