School of Life Sciences, Arizona State University, Tempe, AZ 85281, USA.
Horm Behav. 2011 Jan;59(1):133-43. doi: 10.1016/j.yhbeh.2010.11.002. Epub 2010 Nov 12.
Testosterone produced by the gonads is a primary mediator of seasonal patterns of territoriality and may directly facilitate territorial behavior during an encounter with a potential intruder. Costs and benefits associated with territoriality can vary as a function of habitat, for example through differences in resource distribution between areas occupied by different individuals. We investigated behaviors in response to simulated territorial intrusions (hereafter territorial behaviors) in urban (Phoenix, Arizona) and nearby desert populations of two Sonoran Desert birds (Curve-billed Thrasher and Abert's Towhee). We also examined the degree to which these behaviors are mediated by testosterone (T) and the adrenal steroid, corticosterone (CORT), which can interact with T in territorial contexts. In both species, urban birds displayed more territorial behaviors than their desert conspecifics, but this difference was not associated with variation in either plasma total or in plasma free (i.e., unbound to binding globulins) T or CORT. In addition, neither plasma T nor plasma CORT changed as a function of duration of the simulated territorial intrusion. Urban Abert's Towhees displayed more territorial behaviors in areas where their population densities were high than in areas of low population densities. Urban Curve-billed Thrashers displayed more territorial behaviors in areas with a high proportion of desert-type vegetation, particularly in areas that differed in vegetation composition from nearby randomly sampled areas, than in areas with a high proportion of exotic or non-desert type vegetation. Associations between territorial behavior and habitat characteristics were not related to plasma T or CORT. Understanding the hormonal processes underlying these associations between behavior and habitat may provide insight into how free-ranging animals assess territorial quality and alter their defensive behavior accordingly.
性腺产生的睾酮是季节性领地行为的主要调节者，它可能在与潜在入侵者的遭遇中直接促进领地行为。与领地性相关的成本和收益可以因栖息地而异，例如，由于不同个体占据的区域之间资源分布的差异。我们调查了城市（亚利桑那州凤凰城）和附近沙漠地区两种索诺兰沙漠鸟类（弯嘴嘲鸫和阿布特画眉）对模拟领地入侵的反应行为（以下简称领地行为）。我们还研究了这些行为在多大程度上受到睾酮（T）和肾上腺类固醇皮质酮（CORT）的调节，这些类固醇在领地环境中可以与 T 相互作用。在这两个物种中，城市鸟类比其沙漠同类表现出更多的领地行为，但这种差异与血浆总 T 或游离（即未与结合球蛋白结合）T 或 CORT 没有变化有关。此外，无论是血浆 T 还是血浆 CORT 都不会随着模拟领地入侵时间的延长而变化。在人口密度较高的地区，城市阿布特画眉的领地行为比人口密度较低的地区更为频繁。在沙漠型植被比例较高的地区，城市弯嘴嘲鸫的领地行为比在以外来或非沙漠型植被为主的地区更为频繁，尤其是在与附近随机抽样地区植被组成不同的地区。领地行为与栖息地特征之间的关联与血浆 T 或 CORT 无关。了解这些行为与栖息地之间的关联背后的激素过程，可能有助于深入了解自由放养动物如何评估领地质量并相应地改变其防御行为。
