The monarch butterfly population in Western US decline has reached its lowest point in almost thirty years. After 28 years of monitoring the western monarch population, the Xerces Society for Invertebrate Conservation reported just 9,119 butterflies in 2024. Compared to the 233,394 recorded in 2023, this represents a startling 96% drop. In 2020, there were 1,901 butterflies, the fewest ever recorded, whereas in 1997, there were 1.2 million.

Last year, 33,200 monarch butterflies visited a Nature Conservancy site in Santa Barbara; this year, that number has drastically dropped to just 198 butterflies. Although the exact cause of this dramatic population decline has not been determined, researchers believe that habitat loss and intense heat are key causes. In July, Palm Springs recorded a record-breaking 124°F (51°C) heatwave, and in October, northern California saw another extreme heatwave.

Habitat Destruction and Climate Change Threaten Monarch Survival

The loss of habitat has been a major factor in the monarch butterfly population in the Western US decline, which has been under increasing pressure. The vital host plant for monarch caterpillars, milkweed, has been quickly declining due to urbanization, agricultural expansion, wildfires, and drought. Even in areas where it still exists, much of the milkweed is no longer appropriate for monarch reproduction due to pesticide contamination.

Extreme heat has also had disastrous impacts. Monarchs cannot tolerate temperatures beyond 108°F (42°C) and struggle to survive when temperatures hit 100°F (37.7°C). The sharp drop in population numbers may have been caused by prolonged heatwaves that negatively affected breeding cycles in the western United States last year.

Researchers are cautiously hopeful about the species’ potential to recover despite the concerning decline. The population of monarchs increased by almost 13,000% to 247,246 in 2021 after hitting a record low of 1,901 in 2020. This quick recovery suggests that if environmental conditions improve, the species might grow exponentially.

Also Read: Greenland Ice Sheet Cracking At Unprecedented Rate Due To Climate Breakdown, Study Reveals

Conservation Efforts and Policy Interventions Underway

The U.S. Fish and Wildlife Service declared in December 2024 that it is pursuing the classification of monarch butterflies as a threatened species in response to the decline. If approved, this designation would forbid actions that permanently change habitats, such as removing milkweed and activities like killing or transporting monarchs. Furthermore, proposals for protected wintering sites have been made for 4,395 acres (1,779 hectares) spread throughout seven coastal counties in California.

A final decision is anticipated by December, and public comments on the proposal will be received until March. To better understand the impacts of chemical exposure on pollinators, including bees, moths, and butterflies, the environmental law firm Earthjustice has petitioned the Environmental Protection Agency to mandate pesticide testing on these species.

Data for 2024 has not yet been released by the World Wildlife Fund, which keeps track of eastern monarch numbers. Conservationists emphasize the need to preserve monarch habitats immediately to stop additional losses, especially given the stark drop in the western population.

Also Read: Scientists Are Monitoring Tiny Marine Life From Space: A New Frontier In Ocean Research