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. 与回迁型恋巢迁徙动物不同，漫游性迁徙动物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波动的适应，同时也是为了寻觅资源丰沛的斑块以启动繁殖行为。探究斑块状分布资源区域间的移动对动物适合度的影响，有助于深入理解所有迁徙动物的生态学特征及其对全球变化的响应。 2. 我们将食物可获得性的大范围时空波动数据，与濒危物种暗喉吸蜜鹦鹉（swift parrot, Lathamus discolor）——一种漫游性迁徙动物的定居模式及适合度结果相关联。通过多项预测检验，旨在明确在资源呈时空斑块状分布的环境中，兼性移动是否对暗喉吸蜜鹦鹉个体具有适应性优势。 3. 本研究周期内，暗喉吸蜜鹦鹉的食物资源可获得性波动剧烈。因此，该鹦鹉会迁移至食物最为丰沛的区域进行繁殖，在食物可获得性下降的连续年份中，并不会重返此前的筑巢区域。通过移动，暗喉吸蜜鹦鹉得以利用动态变化的食物资源，并成功完成繁殖。 4. 选择资源最丰沛的斑块进行利用，使得暗喉吸蜜鹦鹉在不同地点的离散繁殖事件之间，能够维持稳定的适合度水平。与在食物匮乏时往往只能产生少量或低质量后代的定居型物种不同，漫游性迁徙为暗喉吸蜜鹦鹉缓冲了极端环境变化带来的负面影响。 5. 本研究首次提供了详实证据，证明在不可预测的环境中，兼性移动与漫游性迁徙对动物个体具有适应性意义。我们的研究数据印证了学界广泛认可的假说：漫游性迁徙能够帮助动物摆脱资源限制的困境。