Most of the range is occupied by the nominate subspecies. In the southern part of the range, L. a. gravirostris, which has a longer bill - especially in males - and tail, is only found on mountaintops of the San Gabriel Mountains to San Diego County. Birds on Mount Pinos are somewhat intermediate. mtDNA cytochrome b and ATP synthase subunit 6 sequence data confirms this arrangement and also suggests that the Mount Pinos birds are closer to L. a. gravirostris (Alexander & Burns, 2006). Apparently, the larger bill of the southern subspecies is an adaptation for being better able to feed on the large, spiny cones of Coulter pines (Pinus coulteri).