Sampling locations for Western Scrub-Jays. Green shading represents heavily forested regions that correspond with high-elevation barriers to dispersal. Numbers correspond to site numbers listed in Table 2. Dot color corresponds to the five nuclear genetic clusters from the Structure results shown in Figure 3. The square outline denotes the region of the hybrid zone depicted in greater detail in Figure 2. Dots with black points inside them represent the three coastal sites away from the hybrid zone that contain one or more interior mtDNA haplotypes. The scrub-jay on the lower left is representative of the coastal type, with bolder blue plumage, a larger blue collar, a bolder eyestripe, whiter undertail coverts, and a larger, more hooked bill compared to the interior type shown at upper right. Note that the range of the species extends into southwestern Canada and into some parts of the Great Plains that are not shown.