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 River Gorge. Lee Vining Glacier carved Lee Vining Canyon and emptied into Lake Russel (the much-enlarged ice age version of Mono Lake). Only the highest peaks, such as Mount Dana and Mount Conness, were not covered by glaciers. Retreating glaciers often left recessional moraines that impounded lakes such as the long Lake Yosemite (a shallow lake that periodically covered much of the floor of Yosemite Valley). With its scrubby sun-baked chaparral, stately groves of pine, fir, and sequoia, and expanses of alpine woodlands and meadows, Yosemite National Park preserves a Sierra Nevada landscape as it prevailed before Euro-American settlement. In