Davies Scott, Sewall Kendra B
Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
Biol Lett. 2016 Jun;12(6). doi: 10.1098/rsbl.2016.0315.
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.
在模拟入侵期间，城市鸟类通常比农村鸟类更积极地保卫自己的领地，但造成这种情况的因素仍不清楚。为了解决这个问题，我们调查了城市和农村雄性歌带鹀（Melospiza melodia）在繁殖期内领地攻击性的差异是否在个体间具有一致性。此外，为了更好地理解这种行为差异背后的生理和生态因素，我们研究了领地行为是否与血浆睾酮（一种导致脊椎动物攻击性增强的激素）和/或同种密度（一个通常与攻击性呈正相关的因素）有关。城市化相关的领地行为差异在繁殖期内个体间具有一致性。然而，城市鸟类增强的领地攻击性与血浆睾酮无关，而且与我们的预测相反，城市地区的同种密度低于农村地区。我们认为，睾酮信号的其他方面以及社会生态环境的特征，如繁殖地点的可用性，可能是城市鸟类领地攻击性增加的基础。
