In the 1980s, about 4.5 million monarchs spent winter on the coast of California and northern Mexico every year. “There would be these forests full of monarch butterflies looking like leaves on trees,” Elizabeth Crone told TIME for Kids. Crone is a professor at Tufts University, in Massachusetts. She studies the species.
In 2020, fewer than 2,000 monarchs were counted in California. This means their population has dropped more than 99%. “The decline has been pretty staggering,” says Hillary Sardiñas of the California Department of Fish and Wildlife (CDFW). In the West, “folks haven’t seen monarchs in a number of years.”
To change that, CDFW, River Partners, and other groups began last year to plant 30,000 milkweeds in California. Monarchs need milkweed to survive. Will this plan save the insect from extinction?
Monarchs and Milkweed
Monarchs have a “very specific relationship” to milkweed, Sardiñas says. They breed only where milkweed is growing. Females lay eggs on it, and monarch caterpillars eat it. The plant is poisonous to many animals, but not to monarchs. Its toxins build up in the butterfly’s body, making the monarch deadly to predators.
In California, milkweed is “virtually gone” because of farming, says Cheryl Schultz, of Washington State University. She’s an adviser on the project. The goal, Schultz says, “is to get enough milkweed into the landscape so that when monarchs are migrating and leave the coast, they can find places to breed.” Wildflowers such as lupine have also been planted. They provide the nectar monarchs need to fuel their migration.
In North America, there are two groups of monarch butterflies. Eastern monarchs live east of the Rocky Mountains. They migrate south to Mexico in the fall and fly back north in the spring. Western monarchs live west of the Rockies. In the fall, they migrate to California and northern Mexico. In the spring, they fly inland .
Both groups are in decline. Scientists blame habitat loss, climate change, and pesticides. But monarch butterflies aren’t on the endangered-species list. The United States Fish and Wildlife Service said last year that monarchs deserved protection but that other species needed more help.
In the Field
On a windy day in March, Asia Jones, of River Partners, led a 15-person crew at the Yolo Bypass Wildlife Area. The Northern California site is one of eight planting locations. Each person carried a bucket of 100 milkweed rhizomes . “They’d walk in a straight line down a row, and every three feet, they’d dig a quick hole and throw in a rhizome,” Jones says. Together, they planted 4,500 rhizomes. They also spread lupine seeds.
Data from the next western monarch count, by the Xerces Society, is due in January. “People like to see these bright-colored orange butterflies,” Crone says. But Schultz thinks it will take “at least a decade” to note a significant increase in their numbers. “Restoring the habitat takes time,” she says. “We’re not going to see results overnight. . . . But I have an incredible sense of hope that we can do this.”
You Can Help
Do your part to protect monarch butterflies. “What I want kids to do is get engaged,” says Hillary Sardiñas, of the California Department of Fish and Wildlife. Plant native milkweed. Grow wildflowers. If you are in the West and see a monarch, take a photo. Upload it to the Western Monarch Milkweed Mapper. “You can help track the migrating monarchs and understand where they are during the year,” Sardiñas says. “That’s super valuable information to us.”