Yosemite National Park is causing the problem. Despite the richness of high-quality habitats in Yosemite, the brown bear, California condor, and least Bell's vireo have become extinct in the park within historical time, and another 37 species currently have special status under either California or federal endangered species legislation. The most serious current threats to Yosemite's wildlife and the ecosystems they occupy include loss of a natural fire regime, exotic species, air pollution, habitat fragmentation, and climate change. On a more local basis, factors such as road kills and the availability of human food have affected some wildlife species. Yosemite National Park has
Yosemite National Park Day in early October. A maximum of 300 hikers, selected by lottery, are permitted to advance beyond the base of the subdome each day, including 225 day hikers and 75 backpackers. The park can be divided into five sections for the day-user—Yosemite Valley, Wawona/Mariposa Grove/Glacier Point, Tuolumne Meadows, Hetch Hetchy, and Crane Flat/White Wolf. Numerous books describe park trails, and free information is available from the National Park Service in Yosemite. Park rangers encourage visitors to experience portions of the park in addition to Yosemite Valley. Between late spring and early fall, much of the park can be accessed for