Figure 1.

The social behaviour network and its responses to social stimuli in gregarious and territorial songbirds. (a) The network as originally described for mammals (modified from Newman 1999). As indicated, nodes of the network are extensively interconnected. All areas concentrate steroid hormones and are involved in multiple forms of mammalian social behaviour. (b) Schematic representation of the present data, showing responses of the network in gregarious (i) and territorial (ii) songbird species. As indicated by the dashed line, modestly gregarious species exhibit greater responses in the extended medial amygdala than do highly gregarious species, but less than the territorial species.