The Purple Martin (Progne subis), a species of significant conservation concern in California, once nested widely in oak, sycamore, and coniferous woodlands throughout the state. Currently, the Tehachapi Mountains of southern California are the only area where significant numbers of Purple Martins are known to still nest in oaks. We surveyed for the Purple Martin and other cavity-nesting birds on a portion of Tejon Ranch in the Tehachapi Mountains during summer 2010. We found 23 nesting pairs of Purple Martins, all using cavities in large Valley Oaks (Quercus lobata) at or near the tops of ridges in open savanna settings. The Aorn Woodpecker (Melanerpes formicivorus) was the most abundant other cavity nester in the area and likely creates the cavities used by Purple Martins. The European Starling (Sturnus vulgaris), considered a serious competitor of the Purple Martin for nest sites in most of the Purple Martin’s range, was rarely encountered near these nest sites.