Life History Evolution in Northern Versus Southern Regions: A Comparative Field Study

该项目旨在区分四种相互竞争的假设，解决在北半球和南半球筑巢的鸟类的蛋窝大小变化。PI将使用比较和实验方法来测试巢穴捕食、食物限制、密度或成虫死亡率——以及可能的相互作用——是否是影响鸟类窝卵数量的重要因素。通过对热带、北温带和南温带森林的物种进行对照比较，将在亚利桑那州、阿根廷和委内瑞拉的森林中观察到8对物种的系统发育和生态匹配。测试将包括在不同地点对共存鸟类的生活史特征（窝的大小、窝的数量、反抗的努力、两次反抗之间的时间间隔、巢穴捕食率、成虫存活率、孵化行为和雏鸟摄食率）的详细测量，以区分不同的假设。

This project is designed to distinguish among four competing hypotheses addressing clutch size variation in birds nesting in northern and southern hemispheres. The PI will use comparative and experimental methods to test whether nest predation, food limitation, density, or adult mortality--and possible interactions--are important factors in affecting clutch size in birds. Eight pairs of species matched for phylogeny and ecology in Arizonan, Argentinan, and Venezuelan forests will be observed with controlled comparisons of species between tropics, north and south temperate forests. Tests will include detailed measurement of life history traits (clutch size, numbers of broods, renesting effort, length of time between renesting attempts, nest predation rates, adult survival, incubation behavior, and nestling feeding rates) of coexisting bird species among sites to differentiate among the alternative hypotheses.