A global conservation collaborative — the International Union for Conservation of Nature — has declared North America’s migrating monarch butterflies endangered.
The designation doesn’t carry regulatory weight — but it sends a strong message that the species is in trouble. Eastern monarch butterflies spend their summers along the eastern seaboard and migrate thousands of miles every fall to winter to Mexico.
Like many pollinator species, the butterflies have faced stark population declines in recent years. Climate change, deforestation and increased herbicide use are all to blame. Still, scientists in New England say there’s a lot more that can be done to protect the insects.
The path to endangered status
Monarch butterflies have been a focus of conservation concern for some time.
IUCN says the species’ population throughout the United States and Canada has shrunk by between 22% and 72% over the last decade.
The eastern population, which migrates to New England every summer, is estimated to have shrunk by 84% between 1996 and 2014.
Monarch butterflies are currently candidates for federal protection under the Endangered Species Act. If approved, that listing would offer them a whole host of new protections. The federal government decided not to list them in 2020.
Steven Reppert is an expert in monarch butterflies and a retired neurobiology professor at the University of Massachusetts Chan Medical School in Worcester.
He says at the time, the monarch’s case wasn’t deemed severe enough.
“There was a priority of animals and plants, and there were 100 that were higher priority for that designation than the monarch butterfly, and they could only do so many designations each year,” Reppert said.
‘Death by a thousand cuts’
Many effects of climate change, including drastic temperature changes, have made it difficult for monarch butterflies to migrate, feed and find safe habitat.
“Climate change is an issue that is really important, particularly with what we’re seeing recently with all the heat, wildfires, droughts,” Reppert said.
Climate change is causing more extreme droughts and heat events across the monarch’s wide range. Droughts can cause milkweed, the food source for their caterpillars, to dry out. That means caterpillars have less food to eat, and it takes longer for them to become a butterfly.
Kent McFarland coordinates the Vermont Butterfly Atlas for the Vermont Center for Ecostudies. He says they face many other threats, alongside climate change. Herbicide use on agricultural fields has contributed to the butterflies’ decline, as has deforestation and habitat loss.
“It’s kind of a death by a thousand cuts,” he said. “It’s not necessarily just one thing.”
Monarchs in New England
The butterflies migrate from central Mexico to the east coast in the summer, which is the time of year when they reproduce.
“They are starting to breed in our fields,” says Heidi Holman, a wildlife biologist at New Hampshire Fish & Game. “Keep your eyes open for that wonderful migration all the way through September.”
McFarland, with Vermont Center for Ecostudies, says that while monarchs are a pollinator species, they aren’t the pollinating powerhouse that bumblebees and other insects are.
Still, he says it’s unclear what the impact would be if they someday stop coming to New England.
The butterfly is Vermont’s state insect.
“To me, that would be the biggest loss — to not have that mysterious phenomena, of, like, this tiny little insect migrating, you know, 3,000 miles,” McFarland said. “That’s the biggest loss for me.”
How to help
Scientists say there’s a lot that individual gardeners, farmers and others in New England can do to support monarch butterflies.
Kent McFarland with the Vermont Center for Ecostudies says next week, starting on July 29, New Englanders can join an international citizen science effort to track monarch populations here, as part of the Montreal Insectarium’s annual Mission Monarch Blitz.
“We’ve made it super easy for people to volunteer,” he said. “You can, you know, just count milkweed in your backyard and see how many Monarch eggs or caterpillars are on it. Or you can go to a local meadow or park and check milkweed for monarchs and caterpillars.”
The blitz runs through the first week in August.
“The great thing is, sometimes with species that we think are endangered and having conservation troubles, there’s not a lot that we can do, just as citizens,” McFarland said. “But with monarchs, there’s actually a ton we can do, because you often can find them right in your backyard, as long as you’re taking care of your backyard properly.”
McFarland says keeping a pollinator garden, even if you have very little space, is a huge help to monarchs. Letting milkweed plants grow and flower rather than weeding them can also help.
Reppart, with the Chan Medical School, says butterfly way stations across New England, like Monarch Watch’s Monarch Waystation Network, a national program with 40,000 contributors, provide monarchs with milkweed and assistance with reproduction and navigation.
He says monarchs are well worth saving.
“If monarch butterflies are no longer around then I think we’re talking about not only the monarch, but a number of other species that are going to be in danger,” Reppert said. “I think we have to be very concerned. If we lose the monarch butterfly, we’re going to lose a lot of other things.”
Holman, with New Hampshire Fish & Game, says now is the time of year to focus on helping monarch butterflies, since more will be arriving in the northeast this summer.
Holman, who also advises the Monarch Joint Venture, a non-profit that supports the migration of butterflies and provides research for their conservation, says people can support habitat for monarch caterpillars by using less herbicides and holding off on mowing their lawns.