Four bioregions converge on Tejon Ranch. The Great Central Valley Bioregion represents the San Joaquin Valley portions of northwestern Tejon. This region is characterized by expansive plains, basins, alluvial fans and terraces among scattered hills and buttes. Although severely impacted by widespread agricultural development, this region remains a major wintering ground and migratory corridor for hundreds of species of birds and is home to many unique biotic communities containing myriad endemic and little-known species.