Photomicrographs of 125I-VIP and 125I-SG binding in several areas that show significant differences between territorial and colonial species (see Tables 1 and 2). Shown are photos from a female melba finch (territorial; A-D) and a female zebra finch (highly gregarious and colonial; E-H). Relative to territorial birds, colonial birds exhibit greater binding of 125I-VIP within the subpallial septum (A, E), and greater binding of 125I-SG within the ventromedial hypothalamus (VMH; B, F) and nucleus of the pallial commissure (nPC; D, H). Conversely, binding of 125I-SG is higher in the infundibular hypothalamus (Inf) of territorial birds (C, G). Scale bars = 500 μm. See Methods for abbreviations (“Nomenclature and abbreviations”).