In the 1980s, about 4½ million monarch butterflies spent winter on the coast of California and northern Mexico every year. “There would be these forests of monarch butterflies looking like leaves on trees,” Elizabeth Crone told TIME for Kids. She’s a professor at Tufts University. That’s in Massachusetts. Crone studies monarchs.
In 2020, fewer than 2,000 monarchs were counted in California. Their population has dropped more than 99%. “The decline has been pretty staggering,” Hillary Sardiñas says. She works for the California Department of Fish and Wildlife (CDFW). In the West, “folks haven’t seen monarchs in a number of years.”
CDFW, River Partners, and other groups want to change that. They began last year to plant 30,000 milkweeds in California. Monarchs need milkweed to survive. Will this plan save the species?
Monarchs and Milkweed
Monarchs breed only where milkweed is growing. Females lay eggs on it. Monarch caterpillars eat it. The plant is poisonous to many animals. But not to monarchs. Its poisons build up in the butterfly’s body. This makes the monarch deadly to predators.
In California, milkweed is “virtually gone” due to farming, according to Cheryl Schultz. She teaches at Washington State University. She’s an adviser on the project. Schultz says the goal “is to get enough milkweed into the landscape so that when monarchs are migrating and leave the coast, they can find places to breed.”
There are two groups of monarch butterflies in North America. Eastern monarchs live east of the Rocky Mountains. They migrate south to Mexico in the fall. They 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 monarchs aren’t on the endangered-species list. The United States Fish and Wildlife Service said last year that the butterflies deserved protection. But it thinks other species need more help.
In the Field
Last March, Asia Jones led a planting crew for River Partners. It worked at the Yolo Bypass Wildlife Area. Team members planted milkweed rhizomes . “They’d walk in a straight line down a row,” Jones says. “Every three feet, they’d dig a quick hole and throw in a rhizome.”
Data from the next western monarch butterfly count is due in January. “People like to see these bright-colored orange butterflies,” Crone says. Schultz thinks it will take at least 10 years for the numbers to go up. “Restoring the habitat takes time,” she says. “But I have an incredible sense of hope that we can do this.”
You Can Help
Do your part to protect monarchs. “What I want kids to do is get engaged,” says Hillary Sardiñas of the California Department of Fish and Wildlife. How? Plant native milkweed. And if you are in the West and you 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 is super valuable information to us.”