Field research at Jasper Ridge

The flight of the butterflies

GIS technology has become the instrument of choice for an array of scientific research. It can map and analyze the presence (or absence) of vegetation, as well as its composition, and help interpret the impact of human beings. It can help track invasive plant species or project backward the presence of faunal populations long gone.

Bill Anderegg

Jon Christensen (shown in 2007 walking the perimeter of Stanford lands) is conducting a historical study of Bay checkerspot butterfly populations. Photo: L.A. Cicero

One of the most famous studies to emerge from Jasper Ridge was performed in the 1960s by biologist and ecologist Paul Ehrlich. For decades, he studied the Bay checkerspot butterfly population until the creature’s disappearance from the preserve in 1997. What history graduate student Jon Christensen calls the “dominant historical narrative” of the butterfly’s local extinction posits that the checkerspot could not survive development. That may be true in many places around the Bay Area, but here, Christensen suggests, the butterfly may have vanished because grazing vanished. In fact, the butterfly’s host and nectar plants benefit from disturbances such as grass fires or munching cows, though not from bulldozers. Christensen is now assembling a comparative history of more than 50 checkerspot populations to test the hypothesis that disturbance is a key to survival for the butterfly.

His study is part of the Spatial History Project, a larger set of digital history investigations funded by the Andrew W. Mellon Foundation and taking place at Stanford’s Bill Lane Center for the West. The project, led by historian Richard White, uses GIS and other technology to analyze disparate spatial and temporal datasets.

The question arises: How did a former environmental journalist working on a doctorate in history end up studying plants and butterflies? Christensen first came to Stanford as a Knight Fellow interested in studying how conservation is measured. Conversations with White led him to realize that the best way of thinking about that subject would be to work in a historical archive. That led him to Ehrlich’s papers, which led him to grazing records, Jane Stanford’s letters, leases, government documents and plant databases.

“I was asking, how can thinking historically deepen our understanding of what happened to the butterflies? How would that affect how we think about reintroduction?

“It was very troubling to watch the butterfly go extinct,” he said. “Now there’s a real possibility that their grassland habitat could disappear. There are fewer wildflowers than before, more invasive species. Without fire and without grazing, grasslands will change. What do we value? What do we want? What will it take to have the kinds of habitats we want?”

The research group working on the butterfly project at Jasper Ridge includes two historians, several biologists, a lawyer (Barton H. “Buzz” Thompson, co-director of the Woods Institute for the Environment) and a soil scientist, who all came together through a Stanford Environmental Venture grant.

“The intersection between science and the humanities can be richly productive,” Christensen said. “We make them rethink their questions, and vice versa. You can have a general-level conversation between sciences and the humanities, but it gets really meaningful here on the particular level. When we talk about particular places and species, that’s when it gets really interesting.”

White’s Mellon grant, along with funding from the Vice Provost for Undergraduate Education, allows the group to hire undergraduate research assistants. The students spent their summer entering data, creating maps and coming up with valuable hypotheses and conclusions regarding the butterflies.
“Decades ago, people didn’t collect the sort of data we would have wanted them to,” Christensen said. “People asked their own questions, not our questions. So we have to figure out how to use their data.”
Among the research assistants was Carrie Denning, an ’08 graduate in history pursuing a co-terminal degree in sociology, and Gabriel Shields-Estrada, a pre-med who loves both biology and statistics. Their respective maps literally illustrate the breadth and audacity of combining the new and the old.

Denning constructed a map of the history of development and conserved areas in towns, cities and counties throughout the Bay Area since 1940. Using city records and plant databases, she hoped to reach conclusions about the reciprocal relationship between conservation and development, which will be relevant to the butterflies in testing hypotheses about their disappearance. Shields-Estrada, meanwhile, created maps depicting the butterflies’ probable historical habitat, which will then be overlain with building and grazing maps.

Only a sophomore, he nonetheless zeroed in on one of the key challenges when you put humanists and scientists in the same room.

“I’ve challenged some assertions, saying there’s not enough data,” he said. “We have different ideas about exactitude.”

His realization that humanists and scientists have different ways of doing things, and that they must work together, is one of the most valuable aspects of collaboration at Jasper Ridge, Christensen said.

“The staff there has been incredibly interested and supportive of our historical research,” he said. “While they are managing dozens of research sites on the preserve, producing results that regularly end up in top science journals, they have given just as much care and attention and thought to our research. That is truly remarkable.”