Early Yosemite animal survey and new study

Sponsored by The Yosemite Area Audubon Society, Biologist Chris Swarth will present a slide program, “Animal Life in the Yosemite: The Scientific Legacy of Joseph Grinnell,” at 7 p.m., Thursday, May 12, at the Oakhurst Methodist Church in Oakhurst on Road 426.

In 1914, University of California Berkeley professor Joseph Grinnell embarked on an intensive six-year ecological study of the animals of Yosemite National Park, the first of its kind in western North America.

The goal was to understand the animals of Yosemite and their “….local distribution…general life areas…, and food relations; breeding habitats and behavior.”

In the course of the survey, which included 957 work days in the park from 1914 to 1920, Grinnell and his students collected 4,354 animal specimens, filled more than 2,000 pages in field notebooks, made more than 250 bird surveys and took 700 photographs.

Now, after a century of dramatic change in California, Mariposa ecologist Swarth has joined other biologists at UC Berkeley and the San Diego Natural History Museum to resurvey areas studied by Grinnell across the state, including Yosemite, to examine animal distribution and abundance and to document changes in those populations over the past 100 years.

Swarth’s talk will highlight selected species accounts of birds; Grinnell’s life and his long, productive career devoted to the study of California’s birds and mammals; and results of the recent resurveys in the current project.

Among the findings of the Grinnell study was the documentation of nesting Great Gray Owls near Glacier Point in 1915, the first breeding record for this secretive owl in the lower 48 states. Of equal or greater significance scientifically was the discovery of two new amphibians previously unknown to science—the Mount Lyell salamander and the Yosemite toad.

Like all YAAS programs, Swarth’s presentation is open and free to the public, although donations to defray program costs and to support the chapter’s local activities are welcome.

YAAS will also lead a field trip Saturday, May 21, to Foresta in Yosemite. Participants should meet at the Midpines County Park at 7:30 a.m. to carpool. The trip is free and the public welcome. Bring binoculars (extra binoculars are usually available), field guides, lunch, snacks and a beverage.

Visit for additional details about the field trip and other activity opportunities offered by YAAS.

Call (209) 742-5579 for additional information about the program or (209) 742-5181 for more information about the field trip, or visit, to learn more about either.