Monarch Butterfly Numbers: Eastern Population Rises While Western Count Stays Low

Few insects capture public attention like the monarch butterfly, known for its striking orange wings and its remarkable long distance migration across North America. The latest population figures give a mixed picture of how these butterflies are faring this year.

In this article we summarize what recent counts show about monarch numbers, looking at both the eastern and western populations. The figures are based on published surveys and assessments from conservation organizations and researchers.

A Tale of Two Populations

North America is home to two main migratory monarch populations, an eastern group and a western group. They follow different routes and spend the winter in different places, and their recent population trends have moved in noticeably different directions.

Eastern Monarchs Rebound in Mexico

According to published figures, eastern monarchs that overwinter in central Mexico occupied about 7.24 acres, which is roughly 2.93 hectares, during the most recent winter season. This is seen as an encouraging sign for the eastern population.

A Second Year of Growth

The reported area marks an increase of about 64 percent compared with the previous winter, when the butterflies occupied around 4.42 acres. According to the published information, this is the second year in a row that the eastern population has increased.

Still Below a Safe Level

Despite the good news, the eastern population remains below the level that scientists consider sustainable over the long term. Researchers recommend an average of about 15 acres of occupied habitat, a level that has not been seen since 2018.

Western Monarchs Remain Low

The western monarch population, which spends the winter along the California coast, tells a more worrying story. According to the Western Monarch Count organized by the Xerces Society, numbers there have stayed very low in the most recent season.

The Western Count in Numbers

The final survey period of the Western Monarch Count ended in January, with volunteers recording 6,464 monarchs across 193 overwintering sites. According to the published results, this was among the lowest totals recorded since the counts began in 1997.

A Long Term Risk

A federal assessment has highlighted the long term risk facing both populations. According to that assessment, over the coming decades eastern monarchs face a substantial chance of disappearing, and the risk reported for the western population is even higher.

Why Habitat Matters

Like many butterflies, monarchs depend on healthy habitat along their migration routes. Areas with flowering plants and suitable vegetation provide the food and resting places that migrating butterflies need to complete their long journeys.

The Role of Nectar Plants

Flowering plants are an important source of nectar for adult butterflies, giving them the energy they need to travel. Monarchs in particular are closely linked to milkweed, the plant on which they lay their eggs and on which their caterpillars feed.

How People Can Help

Conservation groups often encourage people to support monarchs by planting native flowers and milkweed and by protecting existing habitat. Small actions in gardens and public spaces can add up to meaningful support for pollinators over time.

Watching the Fall Migration

Each autumn, monarchs travel south toward their wintering grounds, a journey that draws the attention of nature watchers across the continent. The latest numbers will be followed closely to see whether recent gains can be maintained.