The migratory monarch butterfly—the iconic subspecies common to North America—was declared endangered today by the International Union for the Conservation of Nature (IUCN), the global leading authority on the status of biological diversity. 

The butterfly, known for its twice-yearly, 2,500-mile journey across the continent between its summer and winter grounds, has declined by between 23 and 72 percent in the past 10 years, according to the IUCN.

Though the monarch has long been considered under threat, its listing on the IUCN Red List—the inventory of species’ conservation status—marks the first time it has been officially declared at risk of extinction. 

“It’s hard for people to imagine that something that shows up in their backyard is threatened,” says Anna Walker, who led the monarch butterfly assessment. She’s a member of the IUCN Species Survival Commission Butterfly and Moth Specialist Group, and species survival officer at the New Mexico BioPark Society. 

The threat to monarchs comes from a combination of factors. Habitat destruction over decades in migratory monarchs’ wintering grounds has taken a massive toll. The impact is felt by both the western population, which is found west of the Rocky Mountains and winters on the California coast, and the eastern population, which is found in the eastern U.S. and Canada and winters in Mexico’s fir tree forests. In summer habitats, pesticides used in agriculture have killed monarchs and also milkweed, the plant they lay larvae in. Climate change, too, is an increasing threat as dramatic weather events such as hurricanes and drought become more common along the butterflies’ southern migration routes.  

The western monarch population, less studied and more at risk, has plummeted 99.9 percent in recent decades, from around 10 million in the 1980s to just 1,914 in 2021, according to the IUCN. The eastern population declined by 84 percent between 1996 and 2014. 

Walker commented: -  

“Only one percent of insect species have been assessed by the IUCN—so having the monarch listed is significant. The listing can be a great tool to communicate to the public, and to global authorities, about the urgent need to conserve the butterfly.”

There is hope for the resiliency of monarchs too, Walker says. Insects reproduce quickly “so that gives a great opportunity: If we reduce some threats, the butterfly can do the rest of the work,” she says. 

“We are kind of at this critical window where climate change is going to start having a bigger and bigger impact on species,” she says—so increasing the population numbers now may be critical to setting the butterflies up for success.

Main Source: National Geographic