KEY POINTS

  • Monarch butterfly populations have been declining 
  • The iconic migration that once ran in the millions now only hosts thousands of monarchs
  • This year's western monarch migration only brought less than 2,000 butterflies to California
  • Monarch butterflies are still not protected under the Endangered Species Act

Western monarch butterfly populations are on a decline, and this year's migration showed the species' grim situation. From the millions of butterflies migrating in the 1980s, researchers only recorded less than 2,000 butterflies this year.

Every winter, monarch butterflies move south to California's coast or to the Sierra Madre Mountains in Mexico to stay warm. During the 1980s, these annual events saw millions of butterflies going to the same places each year, clustering trees by the thousands as they bask in the sunlight to warm themselves. The  U.S. Forest Service described the event as a "unique and amazing phenomenon."

As the years went by, however, it became clear that the migrations brought smaller and smaller populations of the iconic species. This week, the Xerces Society for Invertebrate Conservation released the results of the 24th Western Monarch Thanksgiving Count, reporting that only 1,914 monarch butterflies were recorded on the California coast this year.

According to the organization, that's a grim 99.9% decline from the monarch population in the 1980s. That's also a much lower number compared to the previous 30,000-butterfly threshold recorded from 2018 to 2019, despite the volunteers visiting even more overwintering sites compared to the previous year.

"In only a few decades, a migration of millions has been reduced to less than two thousand butterflies," Stephanie McKnight, a conservation biologist with the Xerces Society, said in the organization's press release.

In its blog, the organization noted that the declining trend is not only applicable to the West because the spring and summer sightings of the eastern monarch population have also dropped by 80% since the 1990s when monitoring began, suggesting a substantial population drop within decades.

Monarch Butterfly Endangered Species Act Monarch butterflies fly at the El Rosario butterfly sanctuary in central Mexico. Photo: Reuters/Edgard Garrido

But what has been dooming the species' population? It could be a host of factors including the loss of milkweed and degradation of their overwintering areas. Pesticide-use may also have contributed, while climate change has also caused disruptions in the weather conditions in the butterflies' breeding grounds. 

As the Center for Biological Diversity explained, monarch butterflies need to have large populations to survive threats. However, the numbers appear to show that the iconic migration is close to collapsing.

However, despite the grim numbers monarch butterflies are still not protected under the Endangered Species Act (ESA). As the Xerces Society explained, the U.S. Fish and Wildlife Service (FWS) recently decided that having monarch butterflies protected under the ESA is "warranted but precluded by higher priority actions."

The decision makes monarch butterflies a "candidate" species for the ESA, and its status will be reevaluated every year. But according to the group, the species requires "immediate conservation action."

"In making this decision, the USFWS agrees that monarchs are threatened with extinction — especially the western population, which is in critical condition — but unfortunately did not provide the protection that they so desperately need to recover," the Xerces Society noted in its blog.

Apart from a lack of federal protection, monarch butterflies also don't have state protection. 

So what can we do to protect monarch butterflies? Organizations are also working to help conserve the species, for instance by protecting their habitats or creating new ones. Regular citizens may also do their part through simple actions, the FWS said.

Gardening organically, planting local milkweed and other native nectar plants and educating other people about pollinators would add to the all-important efforts to protect monarch butterflies.