Govind Tekale
The population of Eastern Monarch butterflies has nearly doubled over the past year, according to data released by the World Wildlife Fund and Mexico’s National Commission of Protected Natural Areas. The iconic orange and black butterflies now occupy 4.42 acres (1.79 hectares) of forest in their Mexican wintering grounds, up from 2.22 acres (0.9 hectares) last winter.
Despite this encouraging growth, scientists warn that the population remains dangerously low – about 80% below historical levels and only one-third the size experts believe necessary to avoid migratory collapse.
“While it’s wonderful news that the monarch population increased this year, their numbers are still down by 80% overall and remain just one-third the size needed to avoid migratory collapse,” said Tierra Curry, a senior scientist at the Center for Biological Diversity.
A Fragile Recovery
The annual count measures the area of oyamel fir trees turned orange by clustering butterflies in the mountains of central Mexico. Scientists estimate that approximately 20-30 million monarchs occupy each hectare of forest during winter (with a median of 21.1 million, according to Thogmartin et al., 2017).
According to research published by Semmens and colleagues in 2016, a minimum threshold of 6 hectares (approximately 15 acres) of occupied forest is needed to keep the migration sustainable. The current population, while improved, falls significantly short of this target.
Researchers attribute the recent population growth primarily to favorable weather conditions along the migration route in 2024, with less severe drought than in previous years.
“We recognize the key role of local communities, as well as the support of the government of Mexico in conserving the forest and providing this iconic species with the opportunity to thrive,” said Jorge Rickards, director general of WWF Mexico. “It’s now time to turn this year’s increase into a lasting trend.”
Multiple Threats Remain
The Eastern Monarch butterfly faces numerous challenges to its survival:
Habitat loss continues as milkweed – the only plant on which monarchs lay eggs and their caterpillars feed – disappears from agricultural and urban landscapes.
Pesticide use, particularly herbicides that eliminate milkweed and insecticides harmful to butterflies at all life stages, poses a significant threat. Neonicotinoid insecticides used in crop seed coatings and ornamental plants have been specifically identified as harmful to monarchs.
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Climate change disrupts migration patterns and degrades both breeding habitats in the United States and Canada and overwintering sites in Mexico.
“Monarchs still need big help if we’re going to save these iconic butterflies from the double threat of climate change and pesticides,” Curry said.
Progress in Forest Protection
A separate report shows some improvement in protecting the Mexican forests where monarchs overwinter. Forest degradation in the core zone of the Monarch Butterfly Biosphere Reserve decreased by 10% compared to the previous year. Between April 2023 and February 2024, 9.14 acres of forest were damaged, down from 10.13 acres reported the year before.
The damage stemmed from illegal logging (6.17 acres), natural causes primarily related to drought (2.47 acres), and disease management (0.45 acres).
These forests provide crucial protection for monarchs against wind, rain, and low temperatures during winter. They also support local communities, improve water quality for nearly 6 million people in Mexico City and surrounding areas, and host significant biodiversity.
Conservation Efforts and Legal Protection
In December 2024, the U.S. Fish and Wildlife Service proposed listing the monarch butterfly as threatened under the Endangered Species Act. This decision came after a decade of advocacy by conservation groups including the Center for Biological Diversity, Center for Food Safety, and Xerces Society for Invertebrate Conservation.
“The Fish and Wildlife Service must finalize the listing of monarchs and in so doing protect them from its threats, including and especially pesticides, which have been a major driver of their rapid decline,” said George Kimbrell, legal director at the Center for Food Safety.
The final decision on protected status is expected by December 2025.
Meanwhile, conservation organizations like the Monarch Joint Venture coordinate efforts across North America. Their network of over 135 partners works on habitat restoration, research, education, and community engagement to support monarch recovery.
The Remarkable Migration
Eastern Monarch butterflies undertake one of nature’s most extraordinary journeys. Each fall, they travel up to 3,000 miles from the northern United States and southern Canada to their winter sanctuaries in Mexico’s mountains.
After winter, these same butterflies fly an additional 600 miles north to the southern United States. There they lay eggs on milkweed plants before dying, completing their unique eight-month life cycle. The next three to five generations, each living only three to five weeks, continue the migration northward until reaching breeding grounds in the northern states and Canada.
As pollinators, monarchs contribute to healthy ecosystems across North America. With 80% of agricultural food production depending on pollinators, their protection has widespread benefits beyond the species itself.
Frequently Asked Questions
Why is the Eastern Monarch butterfly population declining?
Eastern Monarch butterflies face multiple threats causing their decline. The main factors include widespread loss of milkweed (their only food source as caterpillars) due to herbicide use in agriculture, pesticide exposure, climate change disrupting migration patterns, and habitat loss in both their breeding grounds and overwintering sites in Mexico.
How many Eastern Monarch butterflies exist today?
Scientists estimate there are approximately 37-62 million Eastern Monarch butterflies based on the 2025 count of 1.79 hectares (4.42 acres) of occupied forest in Mexico. Each hectare typically houses between 21-30 million butterflies. This represents a significant drop from historical numbers, with the population down about 80% from previous decades.
What is being done to protect Monarch butterflies?
Conservation efforts include habitat restoration programs to plant native milkweed and nectar plants, protection of overwintering forests in Mexico, research and monitoring programs, and public education initiatives. Additionally, the U.S. Fish and Wildlife Service has proposed listing the monarch as threatened under the Endangered Species Act, with a final decision expected by December 2025.
How far do Monarch butterflies migrate?
Eastern Monarch butterflies undertake one of the longest insect migrations in the world. They travel up to 3,000 miles from southern Canada and the northern United States to central Mexico in the fall. After overwintering, they begin flying north again in spring, traveling about 600 miles before laying eggs and completing their life cycle.
How can I help Monarch butterflies?
You can help monarchs by planting native milkweed and nectar-rich flowers in your garden, avoiding pesticide use, participating in community science projects that track monarch populations, sharing information about monarch conservation with others, and supporting organizations working to protect monarchs and their habitats through donations or volunteer work.
What would happen if Monarch butterflies went extinct?
The extinction of Monarch butterflies would mean losing a key pollinator in North American ecosystems, potentially affecting plant reproduction and food production. It would also represent the loss of one of nature’s most remarkable migrations and an iconic species with significant cultural importance, particularly in Mexico where monarchs are associated with the Day of the Dead celebrations.
