It’s been a long wait from the initial petition in 2014, through the long slog of status review, to today’s official announcement by the U.S. Fish & Wildlife Service that listing the North American monarch butterfly as endangered or threatened under the Endangered Species Act is warranted, but precluded by higher priority listing actions.
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.
Based on surveys conducted over this recent Thanksgiving weekend, the western population has further plummeted to <2,000 individuals.
The ESA provides for a warranted-but-precluded finding when the Service doesn’t have sufficient resources ($$$) to complete the listing process because the agency must first focus on higher-priority listing rules. Warranted-but-precluded findings require subsequent review each year until the agency undertakes a proposal or makes a not-warranted finding. So in the interim, monarchs will be a Candidate under the ESA.
The Service’s Great Lakes office, which is handling the monarch case, is considering 9 other species with higher- priority status, either ahead in line or with court-mandated decision deadlines: little brown bat, plains spotted skunk, Illinois chorus frog, golden-winged warbler, Blanding’s turtle, Mammoth Springs crayfish, 2 freshwater mussels, and a plant called Hall’s bulrush. Nationwide, 161 species are ahead of the monarch in priority.
While I’m relieved that monarchs weren’t dismissed as “not warranted for listing” based on the Trump Administration’s abyssmal environmental record, I’m especially relieved that the Biden-Harris Administration will be at the helm in future reviews of this magnificent species. A Biden-Harris Secretary of the Interior would be much more amenable to take emergency listing action to list the monarch as endangered or threatened if the best available science so indicated.
For more information on the announcement:
U.S. Fish & Wildlife Service press release
Assessing the Status of the Monarch Butterfly