Biology Student Busts Myths about Monarch Butterfly Habitat

March 10, 2014

Much of what you thought you knew about monarch butterflies may be wrong. Jessica Griffiths, a biology graduate student, has been studying monarchs' overwintering habits for three years, and her discoveries could change the way monarch habitat is protected.

Monarchs spend the winter clustering together at more than a hundred overwintering sites up and down the California coast. Traditionally, those sites have been managed as separate units because it was assumed that monarchs stayed at the same site all winter.

Designing her own hands-on research approach with the help of Professor Francis Villablanca, Griffiths and a team of Cal Poly students tagged monarchs at three different sites in San Luis Obispo County with different colored tags then returned later and counted tagged butterflies. Griffiths' findings suggest that there is much more movement than previously thought, especially among neighboring sites.

"Many monarchs probably use multiple overwintering sites during the season," Griffiths said. "This means that we can't just protect one or even two sites in an area, we need to protect them all. We should be managing at the landscape level, not the site level."

Griffiths also investigated which trees monarchs prefer. People commonly assume the butterflies prefer eucalyptus, but Griffiths thought they only appear to because eucalyptus trees are so abundant.

"This work is based on one of the most basic steps a scientist can take — to test a broadly held notion that has actually never been tested," Villablanca said. "There is no better way to learn the scientific method than to apply it."

Griffiths discovered monarchs don't prefer any species of tree, and they use native conifer species, such as Monterey pine, more often than eucalyptus. "There are management implications for this: we need to revise our current, eucalyptus-centric management techniques and start planting more conifers," Griffiths said.

Griffiths credits this real-world experience with helping her become a better scientist. "When doing field work, you're constantly trying new things, running into obstacles, and working around them. You have to be able to solve problems creatively."

And Learn by Doing, when your subject is monarchs, can have some unexpected rewards. "Sometimes a bird would disturb a cluster of monarchs, and they would all take off in a burst of orange. When so many butterflies take flight at once you can actually hear the shush-shush of their wings flapping. It's incredible," Griffiths said.