Monarchs Proposed for Endangered Species Act Protection

In response to a decade of advocacy by conservation groups, the U.S. Fish and Wildlife Service today proposed to protect monarch butterflies as threatened under the Endangered Species Act. The once-common orange-and-black butterflies have declined by 90% in recent decades, with the latest count showing the second smallest population on record.

If today’s proposal is finalized, monarchs will gain not only protection from harm but also a comprehensive recovery plan and ongoing funding to restore their habitat.

“The fact that a butterfly as widespread and beloved as the monarch is now the face of the extinction crisis is a tri-national distress signal warning us to take better care of the environment that we all share,” said Tierra Curry, a senior scientist at the Center for Biological Diversity. “What’s bad for monarchs is bad for humans, so we have to stop pretending that our health is somehow separate from that of the wildlife our activities are decimating.”

Following the lowest count ever in 2014, the Center for Biological Diversity, Center for Food Safety, Xerces Society for Invertebrate Conservation and renowned Monarch biologist Lincoln Brower petitioned the U.S. Fish and Wildlife Service seeking protection for the butterflies and their habitat under the Endangered Species Act. Monarchs were placed on the candidate waiting list for protection in 2020.

Today’s announcement is a result of a lawsuit filed by the Centers to get a date by which the Service would make a decision on whether to provide protections.

“Today’s monarch listing decision is a landmark victory 10 years in the making. It is also a damning precedent, revealing the driving role of pesticides and industrial agriculture in the ongoing extinction crisis,” said George Kimbrell, legal director at the Center for Food Safety. “But the job isn’t done: Monarchs still face an onslaught of pesticides. The Service must do what science and the law require and promptly finalize protection for monarchs.”

In one of the longest migrations of any insect, at the end of summer eastern monarchs fly from the northern United States and southern Canada to overwinter together in high-elevation fir forests in Mexico. The population size is determined by measuring the area of trees turned vivid orange by the clusters of butterflies.

Scientists estimate that 15 acres of occupied forest is the minimum threshold for the migrating pollinators to be above extinction risk in North America. In winter 2023 there were only 2.2 acres of monarchs, and the 2024 count is also predicted to be bleak because of poor summer weather conditions for breeding and abnormally warm September temperatures that delayed the start of migration.

Migratory monarchs face tremendous threats. Their initial decline was driven by widespread loss of milkweed, the caterpillar’s sole food source, due to increased herbicide use on genetically engineered corn and soybean crops — most notably, Monsanto’s Roundup. All stages of monarchs are harmed by neonicotinoid insecticides used in crop seed coatings and on ornamental plants.

Grasslands and other green spaces that provide wildflowers for nectar-seeking adult monarchs continue to be lost to sprawl development. Millions of monarchs are killed by vehicles annually as they migrate across the continent. In their winter habitat in Mexico, forests and streams are being lost at record rates to grow avocados for unsustainable avocado demand in the United States.

The much smaller western migratory population is down more than 95% since the 1980s. Most monarch butterflies west of the Rocky Mountains overwinter on the central coast of California. In spring and summer, successive generations of eastern and western monarchs spread across the continent in search of milkweed. When days grow shorter the last summer generations roost together in trees as they make their way towards their winter forests.

Non-migratory populations of monarchs live year-round in southern U.S. states. These butterflies have smaller wings and are harmed by parasites that build up on non-native tropical milkweed plants that don’t die back in winter.

In Canada monarchs were listed as endangered under the Species At Risk Act in 2023. In Mexico they are considered a species of special concern. The International Union for Conservation of Nature ranks them as vulnerable, a category denoting threatened status.

The Endangered Species Act is a powerful tool to prevent extinction and help vulnerable species recover. It’s 99% effective at preventing species under its protection from going extinct.