US Butterflies Face Severe Decline, One-Fifth Population Loss in 20 Years

A new report from Binghamton University estimates a 22% decrease in butterfly numbers from 2000 to 2020, urging swift action for conservation.

According to a groundbreaking study from Binghamton University, butterfly populations in the United States have plummeted by more than a fifth over the past two decades, with a staggering 22% decline noted between 2000 and 2020. This shocking figure emerges from extensive analysis, which involved examining 12.6 million butterfly sightings through 76,000 surveys across 35 monitoring programs, including citizen science initiatives like the North American Butterfly Association's Fourth of July counts.

The findings are particularly distressing; approximately one-third of butterfly species analyzed in the study experienced severe population declines. Some species, such as Julia's Skipper, lost over 90% of their populations. According to Prof. Eliza Grames, an assistant professor of biological sciences at the university, the degree of decline observed over such a vast territory is sobering and aligns with broader global trends.

Notably, several species, including the Florida white, Hermes copper, tailed orange, Mitchell's satyr, and West Virginia white, exhibited declines exceeding 98%. Even the previously common West Coast lady butterfly has decreased by 80%, indicating that even adaptable species are not safe from these alarming trends.

The research identifies critical factors contributing to butterfly population declines, including habitat loss, pesticide use, and climate change. Butterflies play an essential role as pollinators, aiding the growth of various plants and crops. Their diminishing populations could jeopardize food production and disrupt entire ecosystems. Additionally, butterflies serve as indicators of broader environmental health; a decline in their numbers often foreshadows complications for other species.

The research indicates the Southwest U.S. is experiencing the most severe declines, likely related to the region's extreme drought conditions. Drought poses a dual threat, harming butterflies directly while simultaneously impacting their food and host plants.

Despite these concerning trends, researchers believe that butterflies have the potential for recovery if urgent conservation measures are enacted. With their short generation times, butterflies can rebound quickly, and small actions such as planting native wildflowers, reducing pesticide applications, and leaving parts of yards unmowed can significantly enhance their survival chances.

Prof. Grames emphasized the necessity for government intervention in addressing these issues. "Insects are fundamental to life on earth," she stated, "and we need conservation actions and policies that support insects." This study underlines the crucial need for immediate attention towards butterfly conservation, potentially influencing efforts like adding species to the International Union for Conservation of Nature (IUCN) Red List of Threatened Species.