Between 1914 and 1920, Joseph Grinnell and colleagues surveyed the mammals, birds, reptiles and amphibians across central California from the floor of the San Joaquin Valley to Mono Lake on the east side of the Sierra Nevada. This early survey provides the vast majority of available knowledge of the fauna of the Park.
The original survey involved 957 person-days of fieldwork. Data archived at the Museum of Vertebrate Zoology includes some 2,000 pages of detailed field notes, 817 photographs, and 2,795 specimens. Joseph Grinnell and Tracy Storer published the collected efforts of this fieldwork in Animal Life in the Yosemite (1924). (Now available online thanks to the National Parks Service -- here.)
In collaboration with Yosemite National Park and the USGS, and with financial support of Yosemite National Park and the Yosemite Fund, and the Sierra Nevada Network Inventory & Monitoring Program, the UC Berkeley Museum of Vertebrate Zoology resurveyed the "Yosemite Transect", to provide updated information on species distributions and on habitat and community changes over the past century.