Data from: Exploiting the richest patch has a fitness pay-off for the migratory swift parrot

1. Unlike philopatric migrants, the ecology of nomadic migrants is less well understood. This life-history strategy reflects responses to spatiotemporal variation in resource availability and the need to find resource rich patches to initiate breeding. The fitness consequences of movements between regions of patchily distributed resources can provide insight into ecology of all migrants and their responses to global change. 2. We link broad-scale data on spatiotemporal fluctuation in food availability to data on settlement patterns and fitness outcomes for a nomadic migrant, the endangered swift parrot Lathamus discolor. We test several predictions to determine whether facultative movements are adaptive for individual swift parrots in an environment where resources are patchily distributed over time and space. 3. Variation in the availability of swift parrot food resources across our study period was dramatic. As a consequence, swift parrots moved to breed wherever food was most abundant and did not resettle nesting regions in successive years when food availability declined. By moving, swift parrots exploited a variable food resource and reproduced successfully. 4. Exploiting the richest patches allowed swift parrots to maintain stable fitness outcomes between discrete breeding events at different locations. Unlike sedentary species that often produce few or lower quality offspring when food is scarce, nomadic migration buffered swift parrots against extreme environmental variation. 5. We provide the first detailed evidence that facultative movements and nomadic migration are adaptive for individuals in unpredictable environments. Our data support the widely held assumption that nomadic migration allows animals to escape resource limitation.1. 与归巢迁徙者（philopatric migrant）不同，漫游型迁徙者（nomadic migrant）的生态学特征迄今尚未得到充分阐释。该生活史策略是对资源可获得性时空变化的适应，同时也是为了寻获资源富集的斑块以启动繁殖活动。探究斑块状分布资源区域间移动的适合度后果（fitness consequence），能够为所有迁徙物种的生态学特征及其对全球变化的响应提供关键见解。 2. 本研究将食物可获得性时空波动的大尺度数据，与濒危快速鹦鹉（Swift Parrot, *Lathamus discolor*）——一种漫游型迁徙者——的定居模式与适合度结果相关联。通过检验多项预测，本研究旨在判断在资源呈现时空斑块状分布的环境中，兼性移动（facultative movement）是否对个体快速鹦鹉具有适应性意义。 3. 在本研究的观测周期内，快速鹦鹉的食物资源可获得性波动极为剧烈。因此，快速鹦鹉会迁移至食物最为充足的区域进行繁殖，且在食物可获得性下降的连续年份中，不会重新返回原筑巢区域。通过移动行为，快速鹦鹉得以利用动态变化的食物资源，并成功完成繁殖。 4. 利用资源最为富集的斑块，使得快速鹦鹉能够在不同地点的独立繁殖事件之间维持稳定的适合度结果。与定居物种（sedentary species）不同——这类物种在食物匮乏时往往只能产生数量稀少或质量低下的后代——漫游型迁徙行为帮助快速鹦鹉缓冲了极端环境变化带来的影响。 5. 本研究首次提供了详实证据，证明兼性移动与漫游型迁徙在不可预测的环境中对个体具有适应性意义。本研究数据也支持了学界广泛持有的假设：漫游型迁徙能够帮助动物摆脱资源限制的困境。