RUI: Hormonal and Body Condition Effects on Natal Dispersal in Birds: Tests of a New Model

9509079出生分散，即从出生地到首次繁殖地的迁移，几乎发生在所有高等脊椎动物身上。这些运动对种群调节、交配系统、遗传学和保护生物学具有重要意义。这个项目的目标是了解鸟类出生扩散运动的生理生态学。一种基于荷尔蒙变化、身体状况和社会刺激之间相互作用的新扩散模型将在圈养和自由生活的鸟类身上进行测试。该模型预测，由于内源性和外部事件的共同作用，皮质酮（一种已知能刺激运动和觅食活动增加的激素）的水平在扩散之前会增加。这刺激了分散行为背后的运动活动，有足够脂肪储备的幼鱼会在那个时候分散。身体状况不佳的鸟类会推迟分散，但会增加它们的觅食活动。兄弟姐妹的分散将减少攻击和/或对食物的竞争，使剩余的幼崽能够改善他们的身体状况并分散。为了验证这一模型，将操纵圈养鸟类的激素谱，并检查它们随后的活动水平与扩散时间的关系。第二组实验将检验皮质酮与自由生活的幼鸟迁徙时间之间的关系。这些实验将确定活动水平、身体状况和激素如何相互作用来控制出生分散。这项研究将对控制出生分散的因素提供重要的新见解。研究结果将为今后脊椎动物体内激素和扩散的研究提供基础，并可能对重要物种的扩散管理具有应用价值。

9509079 Natal dispersal, the movement from place of birth to location of first breeding, occurs in virtually all higher vertebrates. These movements have important implications for population regulation, mating systems, genetics, and conservation biology. The goal of this project is to understand the physiological ecology of natal dispersal movements in birds. A new model of dispersal, based on interactions among hormonal changes, body condition, and social stimuli, will be tested using both captive and free-living birds. The model predicts that level of corticosterone, a hormone known to stimulate increased locomotor and foraging activity, increases prior to dispersal due to a combination of endogenous and external events. This stimulates the locomotor activity that underlies dispersal behavior, and juveniles with sufficient fat reserves will disperse at that time. Birds in poor body condition will delay dispersing, but will increase their foraging activity. Dispersal of their siblings will reduce aggression and/or competition for food, enabling the remaining juveniles to improve their body condition and disperse. To test this model, hormone profiles of captive birds will be manipulated and their subsequent activity levels examined in relation to timing of dispersal. A second set of experiments will examine the relationship between corticosterone and timing of dispersal movements by free-living juvenile birds. These experiments will determine how activity levels, body condition, and hormones interact to control natal dispersal. This study will provide significant new insight into the factors controlling natal dispersal. The results will provide a basis for future studies of hormones and dispersal in vertebrates, and may be of applied value in managing the dispersal of species whose management is important.