title: Agonistic urban birds: elevated territorial aggression of urban song sparrows is consistent within a breeding period.
abstract: Urban birds often more vigorously defend their territories during simulated intrusions than do their rural counterparts, but the factors responsible remain unclear. To address this issue, we investigated whether the disparity in territorial aggression of urban and rural male song sparrows, Melospiza melodia, is individually consistent within a breeding period. Additionally, to better understand the physiological and ecological factors underlying this behavioural difference, we examined whether territoriality was associated with plasma testosterone, a hormone that contributes to elevated aggression in vertebrates, and/or conspecific density, a factor often positively related to aggression. The urbanization-related difference in territoriality was individually consistent within a breeding period. However, the elevated territorial aggression of urban birds was not associated with plasma testosterone and, counter to our predictions, conspecific density was lower in urban compared with rural areas. We suggest that other aspects of testosterone signalling and features of the socio-ecological environment, such as the availability of breeding sites, may underlie increased territorial aggression in urban birds.
authors.affiliation: Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA sdavies1@vt.edu.
authors.forename: Scott
authors.identifier: 0000-0003-3890-7372
authors.initials: S
authors.lastname: Davies
authors.affiliation: Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
authors.forename: Kendra B
authors.initials: KB
authors.lastname: Sewall
mesh_terms: D000374:Aggression / Q000502:physiology*; D000818:Animals; D002947:Cities; D008297:Male; D011156:Population Density; D012098:Reproduction / Q000502:physiology; D046370:Sparrows / Q000502:physiology*; D013731:Territoriality; D013739:Testosterone / Q000097:blood; D014768:Virginia; D014828:Vocalization, Animal
chemical_list: D013739:Testosterone
keywords: repeatability; territorial aggression; testosterone; urbanization