During the breeding season, birds behave more aggressively toward rivals to maintain and defend territories. Resident birds are thought to be more aggressive than migratory birds because they need to maintain a territory year round. Furthermore, birds in urban environments can exhibit more aggressive behaviors than their rural counterparts because of the bolder behavioral characteristics required to colonize urban habitats. In this study, we investigated how migration strategy and landscape composition interact to affect territory defense in two subspecies of Song Sparrow (Melospiza melodia). To evoke an aggressive response, we simulated invasions by broadcasting songs from within a male's territory and recorded the bird's response. We found that neither migration strategy nor landscape composition alone correlated with territorial aggression, but the interaction between these two predictors was significant. Territorial aggression was consistent across landscapes for migratory Song Sparrows but decreased with increasing distance from urban environments for resident Song Sparrows. We hypothesize that migratory Song Sparrows do not spend enough time maintaining their territories to be affected by the landscape composition.
Turcotte, Darlene, "Territorial Aggression Increases Along an Urban Gradient in Resident But Not Migratory Song Sparrows" (2014). Honors College. 188.