MADISON, Wis. — Monarch butterfly populations in North America are in peril.

According to the U.S. Fish and wildlife service, the population East of the Rocky Mountains has declined nearly 85% in the less than 25 years. The western population — which is smaller than the eastern one — has declined more than 97% in that same time span.

“It's probably going to go extinct,” said Karen Oberhauser, director of the UW-Madison Arboretum and a leading researcher on monarchs in North America. 

She said while the western population of butterflies is likely going to be extinct soon, the eastern population levels have held steady over the past decade

“The population needs to be a lot higher to be sustainable over the long-term,” Oberhauser said. “But basically right now we have thousands of people that are working to preserve monarch habitat, and I really think that without these efforts monarchs would be a lot worse off.”

Oberhauser leads some of those efforts in Wisconsin.

One of the largest things killing monarchs is habitat loss from modern farm practices. Monarch caterpillars only eat milkweed, which used to be found in farm fields across the midwest and still was as recently as the early 2000's.

“Since then milkweed has essentially all but disappeared from row-crop fields because of the use of genetically modified crops that allow farmers to spray the fields after the crops have emerged,” Oberhauser said.

Climate change is also killing butterflies, with untimely migration and unpredictable storms killing thousands at once.

“Habitat and weather are the two biggest contributing factors, but we also know that a lot of other things kill monarchs,” Oberhauser said “So in some ways it's kind of like death by a thousand cuts.”

Mosquito sprays, invasive predators, and cars all also contribute to killing the species.

Earlier this week the U.S. Fish and Wildlife Service announced monarchs qualify to be added to the endangered species list, but that they would not receive federal protection.

“We conducted an intensive, thorough review using a rigorous, transparent science-based process and found that the monarch meets listing criteria under the endangered species act,” said Aurelia Skipwith, USFWS Director in a press release. “However, before we can propose listing, we must focus resources on our higher-priority listing actions.”

Oberhauser said the Endangered species Act is the among most effective conservation legislation ever enacted in the U.S. Which is both why she understands the importance of several species being given protection, but also why she was eager to see monarch's receive those protections.

“While I was disappointed,” Oberhauer said. “Just because monarch numbers are declining and because... in my opinion, the protection of the endangered species act would have helped them, I also know that there are a lot of other organisms that are worse off than monarchs right now.”

Monarchs are a flagship species, helping out lots of other plants and animals it shares an ecosystem with. Oberhauser said every day people can help them out..

Planting milkweed in yards or any available space, volunteering to monitor them, or working with or donating to conservation groups have already gone a long way to saving them.

“We need everyone working together to preserve monarchs,” Oberhauser said. “So just spreading the word to their neighbors, their family, their friends what people can do to help monarchs.”