Climate change now driving factor in monarch butterfly decline, says MSU study
Whether they're soaring over a field of flowers or dodging toddlers with nets, butterflies are a quintessential part of the Midwest summer experience. And here in Michigan we are blessed with a particularly gorgeous species: the monarch. But they haven't been around as much these days.
Stateside spoke with Erin Zylstra, post doctoral researcher at Michigan State University, to find out why. Zylstra recently led an in-depth study into what is causing the disappearance of monarch butterflies in mid-Michigan and around the globe, which was recently published in the journal Nature. Their conclusion: Climate change has become a major factor in the species’ decline.
The monarch’s lifecycle and travel habits make them a tougher species to study than butterflies that stick closer to home.
“It’s hard to understand what’s going on with a species that spans three different countries, has this continental scale migration, which occurs over multiple generations. And any number of factors across that annual migration could be involved in that decline.”
Monarch butterflies spend the winter in Mexico, then migrate north toward the southern central United States. Those butterflies breed and lay eggs and then die. Once the new generation of butterflies hatch, they make their way even farther north for the summer--to places like Michigan. Again, the butterflies breed, lay eggs, and die. And the final generation travels all the way back down to central Mexico to overwinter.
What the MSU study found is that weather conditions in monarch breeding grounds can have a major impact on that year’s population. Zylstra explained that monarchs tend to do best when spring conditions are moderate. Not too hot, not too cold, not too wet.
“If the conditions are extreme, if they're much hotter than normal, if they're much drier than normal, or even if they're much wetter than normal, we see the monarch population is not quite as big that year. And so this obviously has implications when we think about climate change.”
Rising temperatures and more erratic weather could spell major trouble for the monarch population, and Zylstra said that addressing climate change at the policy level is the most important things people can do to protect the beloved species. But that doesn’t mean you should stop planting milkweed in your garden. The more habitat, the better, she explained.
“The milkweed populations have really been knocked back by a lot of the changes we've made to the landscape in terms of agriculture and herbicide use. By planting more milkweed in some of these areas, in our yards, in roadsides, in open areas that we let be natural, those are only going to provide more opportunity and habitat for monarchs and other species that use those plants.”