The migratory monarch butterfly, known for its spectacular annual journey of up to 2,500 miles across the Americas, has entered the International Union for Conservation of Nature Red List of Threatened Species as Endangered.

The organization says the butterflies found across the northern hemisphere are now at risk of extinction.

The native butterfly population, known for its migrations from Mexico and California in the winter to summer breeding grounds throughout the United States and Canada, has shrunk by between 22% and 72% over the past decade. Legal and illegal logging and deforestation to make space for agriculture and urban development has already destroyed substantial areas of the butterflies’ winter shelter in Mexico and California, while pesticides and herbicides used in intensive agriculture across the range kill butterflies and milkweed, the host plant that the larvae of the monarch butterfly feed on.

Climate change has significantly impacted the migratory monarch butterfly and is a fast-growing threat; drought limits the growth of milkweed and increases the frequency of catastrophic wildfires, temperature extremes trigger earlier migrations before milkweed is available, while severe weather has killed millions of butterflies.

The western population is at greatest risk of extinction, having declined by an estimated 99.9%, from as many as 10 million to 1,914 butterflies between the 1980s and 2021. The larger eastern population also shrunk by 84% from 1996 to 2014.

Concern remains as to whether enough butterflies survive to maintain the populations and prevent extinction.

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Photo via International Union for Conservation of Nature