The western monarch butterfly population in California experienced a significant decline of 30% last year, according to researchers. The drop in numbers is believed to be primarily due to the unusually wet weather conditions. Volunteers from the Xerces Society, a nonprofit organization focused on invertebrate conservation, reported counting over 230,000 butterflies during their observations around Thanksgiving, compared to 330,000 in 2022.
Although the orange and black insects have shown signs of recovery in recent years, bouncing back from a record low of just 2,000 butterflies in 2020, their population still remains significantly lower than the millions observed in the 1980s.
Scientists attribute the critically low levels of western monarchs in the region to various factors, including the destruction of their milkweed habitat along their migratory route due to housing construction and the increased use of pesticides and herbicides. The changing climate is also considered a key driver of the monarch butterfly's threatened extinction, disrupting their annual 3,000-mile migration synchronized with the arrival of springtime and the blossoming of wildflowers.
'Climate change is making things harder for a lot of wildlife species, and monarchs are no exception,' stated Emma Pelton, a monarch conservation biologist with the Xerces Society. She emphasized the connection between the severe storms experienced in California last winter, known as atmospheric rivers, and the changing climate.
Each winter, western monarchs travel from the Pacific Northwest to California, where they return to the same locations and even the same trees, clustering together to keep warm. Along their migratory route, they breed multiple generations before reaching California, typically arriving in early November. When warmer weather arrives in March, they disperse to areas east of California.
On the other side of the Rocky Mountains, a separate monarch butterfly population migrates from southern Canada and the northeastern United States to central Mexico. Scientists estimate that the monarch population in the eastern U.S. has declined by approximately 80% since the mid-1990s. However, the drop-off in the western U.S. has been even more severe.
The declining numbers of western monarch butterflies highlight the urgent need for conservation efforts. Protecting their milkweed habitat, reducing the use of pesticides and herbicides, and addressing climate change are crucial steps in ensuring the survival of this iconic species. The continued decline of western monarchs serves as a reminder of the delicate balance between human activities and the preservation of biodiversity, urging us to take action to protect these magnificent creatures.
