Volume 2, Issue 10
Yosemite Then and Now
A plaque in UC Berkeley's Museum of Vertebrate Zoology is engraved with a prophetic quote from founding director Joseph Grinnell. In 1910, Grinnell said "the value of the museum will not be realized until the lapse of many years, possibly a century." Only after such a long time passed could researchers benefit from hindsight, comparing today's fauna to the snapshot Grinnell and his colleagues took of California's wildlife during a landmark survey launched in 1904. A century later, UC Berkeley scientists are finally taking that look backward as they follow in Grinnell's footsteps through Yosemite National Park.
Jim Patton, project leader and curator of mammals at the UC Berkeley Museum of Vertebrate Zoology, weighs a mouse (Peromyscus maniculatus) live-trapped from the Merced Grove of giant sequoias. (photo copyright Leslie S. Chow.)
The Grinnell Resurvey Project, launched in 2003 by museum director Craig Moritz, is in the process of revisiting more than 200 locations that Grinnell and his team surveyed. Over the next five years leading up to the Museum's centenary, the scientists will document and collect tens of thousands of mammals, birds, amphibians, and reptiles from a range of habitats representing much of California's unparalleled biodiversity. Part of a National Park Service initiative to monitor wildlife in the country's parks, the Grinnell Resurvey Project is the first inventory of this scale in Yosemite since Grinnell traversed the park eighty years ago.
"Comparing the data from then and now will provide knowledge about the dynamics of the species and the related changes in climate and habitat," says former museum director Jim Patton, who retired from the faculty of the Department of Integrative Biology in 2001.
In many ways, Patton's retirement allows him to work even harder. As the director of field research for the Grinnell Resurvey he spends several weeks every few months in the Sierra Nevadas where his team observes animals of all kinds, traps and releases a variety of critters, shoots photographs, and, of course, takes copious notes.
The original Grinnell Survey is legendary in its attention to detail. The collection consists of more than 4,000 specimens, 2001 handwritten pages of field notes, and 1,400 photographs. Grinnell's system for taking field notes informed the museum's current modus operandi. It's the precision and volume of those records that's enabling the researchers to conduct an accurate resurvey. Indeed, a photographer is documenting the vistas as they currently exist, many from the exact same vantage point where Grinnell's photographer snapped the shutter.
Yosemite Redux, a Flash slideshow created by the UC Berkeley NewsCenter.
"This will allow us to do comparative photographic analysis of the habitats," Patton says.
While Yosemite is protected from logging, other kinds of human intervention have had an impact on the terrain, and as a result, the vertebrate fauna. For example, fire management at Merced Grove has increased the amount of brush in the area, resulting in an inviting habitat for an increasing number of birds like MacGillivray's Warblers, Fox Sparrows, and others.
"Sometimes change can be good," Patton says.
On the other hand, pikas and alpine chipmunks were observed at elevations more than 1,000 feet higher than where Grinnell's team spotted them. Why?
"It could be indicative of a climate shift forcing them to move to a higher, cooler elevation," Patton says. "Some might say that's a symptom of global warming. That could be trouble for the species though if they keep moving up into the mountains until they can't go any higher."
Other animals not noted by Grinnell, like the western harvest mouse and the Pinyon mouse, were caught by Patton's team. The latter has expanded its range from an approximate elevation of 8,500 feet on the eastern Sierran slopes up to 10,400 feet into the Park over the course of a century. As more data is gathered, the researchers hope to identify the reason for the shift in the distribution and population. The researchers are employing techniques Grinnell could only have dreamt of, including molecular genetic analyses.
While California is recognized in the conservation community as a megadiversity region, Patton points out, it's also under increasing pressure from population growth, land use changes, fires, and drought. To that end, the "then and now" survey of California's fauna could inform the sustainable development of the state. Meanwhile, he adds, it could also validate models used to predict how myriad variables, from changes in land use to shifts in climate, could affect the state's biodiversity. In that way, looking to the past may help us prevent problems in the future.
"Thanks to Grinnell and his team's rigorous inventory of species, the museum has a historical database that's unparalleled anywhere else in the world," Patton says. "The ability to make such detailed comparisons between today and 80 years ago is just remarkable. It's time to put that database to use."