The Red Crossbill (Loxia curvirostra) is notable for its extensive morphological and vocal variation, which may represent a complex of incipient and cryptic species differing by flight call. To date, at least 10 distinct flight-call groups have been identified in North America. To our knowledge, however, the flight calls of the Red Crossbills of southern California have not been studied. To begin to address this deficit, we recorded Red Crossbill flight calls at 17 locations in and near the Transverse and northern Peninsular ranges from January 2011 through April 2014. These crossbills were associated with multiple species of conifers, including Jeffrey Pine, Sugar Pine, White Fir, and ornamental plantings of non-native Aleppo Pine, at elevations from 380 to 2700 m. Analysis of sonograms of these flight calls reveals primarily type 2 of Groth’s (1993) classification system but also migrants of type 3 in the Mojave Desert.