RENO, Nev. Butterfly populations in California are declining and, in some cases, moving to higher elevations in the Sierra Nevada due to climate change and loss of habitat, according to a study authored by biologist Matthew Forister, a University of Nevada, Reno assistant professor in the College of Science.
"Caterpillars are important herbivores as well as a food source for small mammals and birds," Forister said. "They play a significant role in an ecosystem. Butterflies are used as indicators of the health of the environment worldwide. What's happening here is a globally recognized pattern, though this study is unique in representing North America."
The study, to be published this week in the Proceedings of the National Academy of Sciences, is based on 35 years of data collected by Arthur Shapiro, professor of evolution and ecology at the University of California, Davis, and analyzed by a team headed by Forister, who was also a former doctoral student in Shapiro's lab.
The analysis of the data found that climate has changed over the past three decades, with an increase in both maximum and minimum daily temperatures, shifting some low-elevation butterfly populations to higher elevations.
For example, in recent years the field skipper butterfly seemed to react to global warming by expanding its range from northern California to central Washington State and Idaho. Now it's jumped the Sierra and invaded the western Great Basin, becoming established in California's Sierra Valley, and in the Carson Valley and near Verdi in Nevada. It also has been very responsive to spring temperatures, emerging nearly a month earlier than it did near Sacramento 30 years ago.
Forister has been working on analyzing the data for more than five years. For the data on butterflies to be meaningful, decades of consistent sampling is required with long-term data sets, he said.
The data are based on biweekly butterfly surve
|Contact: Mike Wolterbeek|
University of Nevada, Reno