After a thorough assessment of the monarch butterfly’s status, the U.S. Fish and Wildlife Service (Service) has found that adding the monarch butterfly to the list of threatened and endangered species is warranted but precluded by work on higher-priority listing actions. With this decision, the monarch becomes a candidate for listing under the Endangered Species Act (ESA), and its status will be reviewed each year until it is no longer a candidate.
“We conducted an intensive, thorough review using a rigorous, transparent science-based process and found that the monarch meets listing criteria under the Endangered Species Act. However, before we can propose listing, we must focus resources on our higher-priority listing actions,” said U.S. Fish and Wildlife Service Director Aurelia Skipwith. “While this work goes on, we are committed to our ongoing efforts with partners to conserve the monarch and its habitat at the local, regional, and national levels. Our conservation goal is to improve monarch populations, and we encourage everyone to join the effort.”
Over the past 20 years, scientists have noted declines in North American monarchs overwintering in Mexico and California, where these butterflies cluster. Numbers in the larger eastern population are measured by the size of the area they occupy. At a density of roughly 8.5 million monarchs per acre, it is estimated that the eastern population fell from about 384 million in 1996 to a low of 14 million in 2013. The population in 2019 was about 60 million. The western population, located in California, saw a more precipitous decline, from about 1.2 million in 1997 to fewer than 30,000 in 2019.
The Service used the best scientific information to evaluate threats to the monarch, including habitat loss, climate change, and exposure to pesticides, and used a model to create millions of simulations of future conditions to estimate the risk of extinction.
The Service prioritizes work on imperiled species through its National Listing Workplan. Currently, listing actions for 161 species on the workplan (64 percent) are a higher priority than the monarch. These species include plants, insects, freshwater mussels, fish, birds and mammals. Obligations to meet court orders and settlements due to litigation can affect when the agency works on some species.
“America’s farmers welcome the U.S. Fish and Wildlife Service’s decision to continue monitoring the health of the monarch butterfly population,” said American Farm Bureau Federation President Zippy Duvall. “Preserving natural surroundings for America’s wildlife has long been a priority for America’s farmers and ranchers. More than 140 million privately-owned farm and ranch acres are enrolled in voluntary conservation programs, providing habitats for countless animals and insects, including the monarch.” Farm Bureaus across the country have been involved with state and regional planning efforts for the monarch – joining forces with the energy and utility sectors, those who manage natural areas, and our urban hubs across the country – to meet ambitious goals for the species. The warranted but precluded decision will give all stakeholders time to continue conservation and research efforts.
Because monarchs are solely dependent on milkweed during the caterpillar stage, efforts to boost the number of milkweed stems across the country are the basis for many monarch conservation plans.
More information about the Service’s findings on the monarch and tips on how to help conserve monarch butterflies are available here: https://www.fws.gov/