The Western monarch population, which overwinters along the California coast, has suffered one of the most dramatic wildlife declines ever recorded. From an estimated 1.2 million butterflies in 1997, winter counts have repeatedly fallen to tens of thousands or fewer, with several recent seasons ranking among the lowest on record. Preliminary data from the 2024–2025 winter indicates that Western monarch numbers remain critically low, placing the population at continued risk of collapse.

The Eastern monarch population, which overwinters in a small region of central Mexico, has also experienced severe losses. From an estimated 384 million monarchs in 1996, the population has declined by approximately 90 percent since the 1990s, with repeated years of dangerously low overwintering acreage. While some years show modest rebounds, overall trends continue downward, and recent data suggest that population instability has intensified in the past decade due to compounding environmental pressures.

The primary drivers of these declines are well documented and ongoing: widespread pesticide and herbicide use, accelerating climate change, prolonged drought, and the continued loss and degradation of breeding, migratory, and overwintering habitat. Grasslands have been converted to agriculture and urban development, reducing native milkweed—the sole food source for monarch caterpillars and the only plant on which monarchs lay eggs—across much of the species’ range. At the same time, critical overwintering habitats are being damaged or destroyed, undermining monarch survival during their most vulnerable life stage.

In December 2020, the U.S. Fish and Wildlife Service concluded that listing the monarch butterfly as Threatened or Endangered under the Endangered Species Act (ESA) was warranted, based on extensive, peer-reviewed scientific analysis. However, in December 2025, the long-anticipated final decision was once again delayed, leaving monarchs without the federal protections scientists have repeatedly said they need.

Compounding this uncertainty, the current administration has proposed rolling back the Endangered Species Act to weaker 2019 regulations, citing economic growth and development priorities. These proposed changes would reduce protections for imperiled species and their habitats at a time when monarch populations are already teetering on the edge.

Despite these challenges, monarch recovery is still possible—but only with immediate, sustained conservation action. Protecting breeding habitat, restoring milkweed and nectar corridors, safeguarding overwintering sites, and engaging communities at every level are all essential. From backyard gardens to landscape-scale restoration, every effort matters.

Time is no longer on the monarch’s side.
The science is clear.
The need is urgent.
Your support is critical.