Scientists Revisit Historic Animal Diversity Survey

At the UC Berkeley Museum of Vertebrate Zoology, mounted moose heads are small potatoes compared to the thousands of animal specimens collected under the guidance of museum founding director Joseph Grinnell starting in 1908.

The museum, holding some of the largest collections mammals, bird, reptiles and amphibians in the world, is a result of decades of research on vertebrate animal diversity in California. Carried out by Grinnell and his colleagues, the research covered hundreds of sites and produced thousands of pages of field notes and photographs.

"(Grinnell) wanted to describe the fauna of California in such a way and in such detail that that basic description could provide the baseline information for us today," said James Patton, curator of mammals at the museum and professor emeritus in the UC Berkeley Department of Integrative Biology.

Indeed, almost one hundred years later, UC Berkeley researchers are doing it all over again. In what they call the "Grinnell Resurvey Project," they are revisiting more than 200 of the original sites, documenting animal diversity and comparing the results to Grinnell's data. In doing so, they plan to examine the relationship between changes in animal communities and geographical ranges to changes in habitat and climate, a goal that Grinnell had originally intended for the project, researchers say.

"We have a detailed knowledge of terrestrial fauna of California in early 1900s. So we can go ask the question: ‘What kind of changes have taken place and why might have those changes taken place?'" Patton said.

Fieldwork started on the Yosemite site in 2003 and will be completed this summer. Researchers are taking specimens from the site and recording the abundance of various species using live trapping, marking and release methods.

They are also documenting habitats by recording the surrounding vegetation and taking digital photographs of the sites, using methods of documentation first established by Grinnell and now used around the world.

So far, researchers in Yosemite have found significant changes in the elevation of certain species that may be due to different types of local habitat modifications.

For example, the Montane shrew has been found to replace the Trowbridge shrew as the most abundant species in the valley floor. Researchers believe this may be linked to the National Park Service's attempt to restore Yosemite's dry meadows to moist conditions, a habitat preferred by the Montane shrew.

Changes in species distribution can also result from long-term climate changes due to global warming, researchers say. For example, the pika, rabbit-like animal that is highly sensitive to hot temperatures, has shifted upwards in its elevational range, in concordance with increasing summer temperatures.

Researchers hope that examining these species will help in generating predictive models of how vertebrate diversity responds to changes in habitat.

"With the historical data and today's data, you have two points of real data that you can use to help model what's going to happen in the future and what's the rate of change," Patton said.

Researchers may be able to use such information to help protect diversity in the area. This is important considering the fact that, according to researchers, California possesses a high degree of threatened species.

For example, the alpine chipmunk, like the pika, has shown an increase in elevational range. But due to its smaller distribution, further movement upward could result in eventual loss of the species, Patton says.

"Grinnell and (museum cofounder Annie) Alexander could already see the effects of humans on natural systems in California ... So rather than speculating about the effects of land use change or climate change or habitat loss on the fauna, we can really document it and find ways to predict it, so that we can look at different options for the future in in terms of habitat protection," said Craig Moritz, museum director and UC Berkeley integrative biology professor.

Besides statistical modeling tools, the study has benefited from developments in research technologies over time. Researchers can now use the tools of molecular genetics to analyze DNA from both current samples and the skin of historic samples, allowing them to observe the nature of genetic change in the populations, Patton said.

They are also using new geographic information systems (GIS), which can compare local climate data in California from previous decades and be used to create climate models from Grinnell's day. It also allows scientists to project what kinds faunal changes might occur due to the effects of global warming, for example.

"We're using techniques that weren't even considered back in the Grinnell days," Patton said.

Researchers are currently working on making the information available to the public on the Internet. After they wrap up the survey in Yosemite, they will start on the Lassen Peak area.

"Sometimes we stay in the public campgrounds along with hundreds and hundreds of other people over summer. Other times we're up in the back country ... It's wonderful. It's the best part of the job, I can't believe I get paid to do it, really," Moritz said.

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