Museum scientists to repeat landmark 80-year-old Yosemite wildlife survey
|Yosemite Redux: Flash slideshow|
BERKELEY – A party of biologists from the University of California, Berkeley, is camping out around Yosemite National Park this summer, reprising a survey of park wildlife first conducted more than 80 years ago by an earlier generation of UC Berkeley scientists.
The survey by members of the Museum of Vertebrate Zoology follows the same transect - from the Central Valley through Yosemite Valley to Mono Lake - as did Joseph Grinnell and Tracey Storer in their landmark survey of Sierra Nevada birds, mammals, reptiles and amphibians between 1914 and 1920. At the time, Grinnell was director of the museum and a zoology professor at UC Berkeley.
The National Park Service last year asked the museum scientists to conduct a new survey, since no complete assessment of park wildlife had been done since Grinnell's day. The team began its work in May.
"With this survey, we are hoping to get new baseline data to compare to the Grinnell and Storer surveys early in the 20th century and see if there have been any changes in the abundance or distribution of species in the park," said Yosemite's lead wildlife biologist, Steve Thompson. The park service is committing $41,000 to the survey, Thompson said, while museum staff will donate about twice that amount in time and effort.
The survey is part of a National Park Service initiative to inventory and monitor wildlife in the national parks, but it coincides with the museum's wish to commemorate its 100th anniversary with a major project of value to California. By the museum's centennial in 2008, scientists there hope to have resurveyed many of Grinnell's original transects around the state.
"Yosemite is the crown jewel of the national park system and also of our project, because it was such a high profile piece of work by Grinnell in the first place," said museum director Craig Moritz, UC Berkeley professor of integrative biology.
The survey of over 20 sites in Yosemite will take about three years and involve most museum scientists and several students. It is being conducted concurrently with resurveys of Grinnell's other transects, including Sequoia/Kings Canyon national parks, Lassen National Park, the Trinity Alps, the Lower Colorado River, Death Valley and the Mojave Desert.
While new data gathered this summer have not yet been thoroughly analyzed, a few surprises have already emerged. In Yosemite Valley, the formerly most abundant species of shrew has been supplanted by a species previously known only from higher elevations in the park. And, while looking at mammals in the northwest corner of the park around Merced Grove and Crane Flat, the scientists discovered that the golden mantled ground squirrel had disappeared from many areas, essentially moving to elevations 500 feet higher.
Joseph Grinnell was an eminent biologist of the early 20th century, known for his concept of the ecological niche - the role an organism plays in the broader ecology of an area - and for his insistence on systematic and careful surveys of wildlife. Desiring to establish a research center that would rival the major natural history museums of the East Coast and Europe, he accepted an offer in 1908 to create the Museum of Vertebrate Zoology at UC Berkeley. He directed it until his death in 1939, realizing his dream and influencing generations of biologists in the areas of ecology, vertebrate systematics and evolutionary biology.
"What's astonishing about Grinnell's work - and the only reason we can do this resurvey now - is the extent to which he kept highly detailed records. His field notes are extraordinary," said Moritz, an evolutionary biologist who specializes in lizards of the Australian rain forests. "He set up a whole system of taking field notes that's been perpetuated through the history of the museum and has spread out to other places as well. What makes this museum special is that we have so much data per specimen. and it's so well organized. That's Grinnell's legacy."
The National Science Foundation just awarded the museum a grant to put all the field notes of Grinnell and his colleagues on the Web in a searchable database. The notes themselves comprise 13,000 pages, and are accompanied by 2,000 photos and tens of thousands of specimens in the museum's collections.
Among Grinnell's legacies was the first field survey of Yosemite National Park conducted at a time when the park's unique and fragile habitat was feeling the pressure of increasing tourism. His survey led to recommendations for managing and preserving the park, among them, elimination of agriculture and removal of a small zoo from the valley.
Yosemite's Thompson said he keeps a copy of Grinnell's published study near his desk and refers to it frequently.
"Grinnell had a very prominent place in the development of science in the park service," he said. He expects to make full use of the current survey.
The Yosemite field notes once generated by Grinnell, Storer and their team alone number 2,000 pages, and the combined team put in about 1,000 hours of field work in the park.
"We're going back through the field notes containing all the original information to do an exact comparison between today and 80 years ago, which is a remarkable thing," said James Patton, who has been leading this summer's survey teams. Patton is a curator in the museum, a UC Berkeley professor emeritus of integrative biology and an expert on small mammals.
To make these comparisons, the team is revisiting initially about 10 of the 22 sites surveyed by Grinnell and Storer within the boundaries of Yosemite. Assuming funding comes through, museum scientists will revisit the remainder of the 22 "Grinnell" sites in the park, plus add some new ones in the northern tier, an area of the park Grinnell did not visit.
"Soon after I arrived at the museum (in 2000), I sat down and read a paper Grinnell wrote in 1910 on the uses of a research museum in which he laid out really, really clearly the purpose of building a museum the way he did," Moritz said. "He actually specified that his hope was that future curators and zoologists could come back in 100 years and look at the effect of human changes to the landscapes on the vertebrate fauna. As soon as I read that, it was really clear what we had to do for our centenary - do what Grinnell told us to do and resurvey his transects."
While the earlier biologists used shotguns, leg-hold traps and snap traps to do much of their surveying and collecting, the current team will capture and release most of the animals. Bird populations will be assessed by observation and point counts, while mammals will be sampled through live trapping and release. A few small mammals will be taken to ensure correct identification and to provide reference material, as will some amphibians and reptiles.
This year so far, UC Berkeley biologists have made four trips to the park, often packing in their food and traps on mules. The first was in May to survey Yosemite Valley; followed by a trip in June to the northwest part of the park near Crane Flat and Merced Big Trees; one in early July to the Glacier Point area; and one in late July to Lyell Canyon. The team set off Aug. 5 for a 10-day survey near the Tuolumne area at Glen Aulin. During the summer the team is comprised of between four and eight people, including park service biologists, who are surveying mammals, birds, reptiles and amphibians. A separate team of herpetologists will descend on the park this fall and next spring to look for amphibians like frogs and salamanders.
A museum photographer will follow up by taking photos of the same areas as did Grinnell and his crew, ideally from the exact same spot.
Though the study is designed to assess the status of all vertebrates, there are some animals the park is specifically interested in because their status is currently unknown. These are not the obvious large or pervasive animals - bears, deer, owls and others - that have been the subject of previous targeted studies. Instead, the list includes a pocket mouse, two species of grasshopper mouse, six species of shrews, six species of chipmunks, and reptiles like the Western fence lizard, Western skink, sagebrush lizard, night snake and sharptailed snake.
"We're learning there have been ecological changes within the park that until now we haven't been able to document adequately," said Leslie Chow, a UC Berkeley graduate now serving in Yosemite as a research wildlife biologist for the U.S. Geological Survey. "We view the park as relatively pristine because we don't allow logging, but other actions - things like suppressing fires for a hundred years - have had an impact."
Moritz expects that other transects they survey will exhibit much greater change.
"It's our best protected landscape in California, so we are expecting Yosemite to be the benchmark against which we can compare other transects," he said.
If Thompson and Chow have their way, museum scientists will regularly visit the park to document the changes occurring in species distribution and population.
"Grinnell established a baseline in the teens, and hopefully we can convince the park that this sort of monitoring needs to be done on a more regular basis," Chow said. "We'd like to get the museum involved so it will come back every 20 years and do something like this."
"I hope this cooperation is just a springboard for further work we can do with the Museum of Vertebrate Zoology," Thompson said. "We do need the data."