Meeting Abstract
Urbanization is a critical form of environmental change that can affect the physiology and behavior of wild animals and, notably, birds. One behavioral difference between birds living in urban and rural habitats is that urban males show elevated territorial aggression in response to simulated social challenge. This pattern has been described in several populations of song sparrow, Melospiza melodia. Such behavioral differences must be underpinned by differences in the brain, yet little work has explored how urbanization and neural function may be interrelated. Our previous work compared a marker of neural activation in response to song playback (the immediate early gene FOS) and expression of a neuropeptide involved in territorial aggression, arginine vasotocin (AVT), within nodes of the brain social behavior network of urban and rural male song sparrows. This initial work implicated both FOS expression and AVT in mediating behavioral adjustments to urbanization in male song sparrows. However, we were unable to correlate these brain measures with birds’ territorial responses. In the present study we again compared FOS and AVT immunoreactivity within nodes of the social behavior network from urban and rural males but also correlated these measures of male territorial aggression and quantified co-localized protein expression. This approach allowed us to determine if neuropeptide expressing neurons were activated during elevated aggressive responses. Our findings implicate neural activation of neuropeptide-expression cells within the social behavior network of the brain in regulating the well-established differences in territorial behavior among song sparrows living in rural and urban habitats. We discuss how changes in neuropeptide systems could underpin both facultative and evolutionary adaptation to urban habitats.
