vireos have recolonized the Santa Clara River in Ventura County, where 67 pairs nested in 1998, and the Mojave River in San Bernardino County. The northernmost reported sighting in recent years is of a nesting pair of least Bell's vireos near Gilroy in Santa Clara County in 1997. Roughly half of the current least Bell's vireo population occurs on drainages within Marine Corps Base Camp Pendleton in San Diego County, particularly in the lower Santa Margarita River. References External links Bell's Vireo Species Account - Cornell Lab of Ornithology Bell's Vireo - Vireo bellii - USGS Patuxent Bird Identification InfoCenter Bell's Vireo synopsis - Wisconsin Department of Natural Resources Article on the Chino Hills oil spill of 1994 and its effect on the environment (including Least Bell's vireo) - U.S. Fish and Wildlife Service - Pacific Region Video of Least Bell's Vireo Bell's vireo Native birds of the Plains-Midwest (United States) Fauna of the Sonoran Desert Fauna of the Yuma Desert Fauna of the Chihuahuan Desert Fauna of the Lower Colorado River Valley Birds of the Rio Grande valleys Birds of Mexico Bell's vireo Bell's vireo