Science & Technology

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The Western Monarch Butterfly population has been declining since the 1990s. Scientists worried that if this trend continues, the beautiful creatures might become extinct. Thankfully, there has been a notable increase in the monarch population over the last year, giving scientists hope that they will survive.

In the early 90s, between three and ten million monarch butterflies migrated to California for the winter. Between 2020 and 2021, only about 2,000 were counted in the entire state. Astonishingly, the numbers increased in 2021 to around 250,000. While researchers were happy about the dramatic increase, it left them wondering how this happened.

Migration Patterns of Monarchs

The migration patterns of monarch butterflies are complicated. The butterflies east of the Rocky Mountains travel to Mexico in the fall, where the weather is warm and there are wooded areas for them to live. Those west of the Rockies travel to the California coastline, also in search of a warmer climate.

(Photo by Yichuan Cao/NurPhoto via Getty Images)

The butterflies then go into a hibernation-like mode called “diapause” that allows them to extend their short life by a few months. Only about one-third of the insects survive this period. The ones that make it through awake from their slumber and find a mate. The females then head to Nevada to locate milkweed to protect their eggs and feed the caterpillars once they hatch.

The Remarkable Return

The complexity of a monarch’s life cycle and migration process makes it difficult to pinpoint what caused their grand return. However, scientists have narrowed it down to a handful of possibilities.

• Mild weather conditions: Monarchs cannot survive harsh climates, nor can milkweed.
• The perfect amount of rain at the ideal time: Milkweed does not grow enough to protect the eggs and feed the caterpillars if the right amount of rain does not fall.
• Drought conditions: Less rain means fewer crops which equals fewer pesticides to kill the butterflies.
• Wildfires: Wildfires prepare the soil for new wildflower growth that increases survival.
• Perhaps the winged creatures are a “negative density-dependent” population: This means the butterflies may have a better chance at survival when there are less of them to feed and protect.
• Difficulty tracking the species: It is possible that researchers do not know of all the places that monarchs migrate, live, and reproduce.
• A combination of some or all the above ideas: Many scientists believe the jump in population can only have happened if one or more of these explanations occurred.

(Photo by Brittany Murray/MediaNews Group/Long Beach Press-Telegram via Getty Images)

Western Monarch Mystery Challenge

Washington State University put together a contest of sorts to learn more about these beautiful insects. The Western Monarch Mystery Challenge was started in 2020 by scientists who are hopeful to learn more about the activities and habits of monarch butterflies during the spring months. They ask anyone who sees a monarch within those months to report it. The information reported will be used toward efforts in conserving the monarch population. The challenge runs from February 14 to April 22, 2022, and participants have a chance to win a $50 REI gift card.