Seasonal Patterns of Fat Deposits in Relation to Migratory Strategy in Facultative Migrants
Seasonal Patterns of Fat Deposits in Relation to Migratory Strategy in Facultative Migrants
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DOI：
10.3389/fevo.2021.691808
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发表时间：
2021-06-29
影响因子：
3
通讯作者：
Watts, Heather E.
中科院分区：
文献类型：
--
作者：
Cornelius, Jamie M.;Hahn, Thomas P.;Watts, Heather E.
对迁徙的生理准备通常反映迁徙策略。候鸟为长途飞行提供燃料主要是用脂肪，但携带多余的燃料成本很高；因此，出发前沉积的脂肪量通常反映预期的飞行持续时间或两次加油的间隔距离。季节性迁徙前的脂肪沉积在正常的季节性候鸟中有很好的记录，但对于更多兼性物种的描述较少。我们分析了鸣禽亚科几个兼性候鸟分类群中自由生活鸟类的脂肪沉积，包括家雀(Hahemhous Micianus)、美洲金雀(Spinus Tristis)、松小尾雀(Spinus Pinus)和四个不同的北美生态型红十字鸟(Loxia Curvirostra)，以评估兼性迁徙期间的季节性脂肪沉积。我们的数据表明，季节性脂肪沉积的程度与这些兼性分类群的迁徙趋势相一致。具体地说，具有季节性可预测年运动的游牧红十字鸟表现出与迁徙时期一致的相对较大的季节性脂肪沉积。相比之下，被认为在游牧活动的时间和开始方面更具变异性的松树西斯金雀在迁徙季节脂肪沉积的峰值较小，而部分迁徙的美国金翅雀和留宿的家雀没有表现出与迁徙时期一致的峰值。在红十字鸟中，与松树生境密切相关的生态型的脂肪沉积峰值较大，与秋季迁移期一致，具有较高的翅膀负荷；而与云杉、道格拉斯冷杉和铁杉相关的生态型，其脂肪沉积的峰值较大，与春季迁移期一致，翅膀负荷较低。我们的结论是，脂肪沉积的种群平均值确实反映了这些物种的兼性迁徙策略，以及研究地点冬季产热的挑战。红十字鸟生态型间季节育肥和翅重的差异与其迁徙生物学存在差异的可能性是一致的，我们根据不同针叶树种的繁殖期和物候对这种差异进行了讨论。
Physiological preparations for migration generally reflect migratory strategy. Migrant birds fuel long-distance flight primarily with lipids, but carrying excess fuel is costly; thus, the amount of fat deposited prior to departure often reflects the anticipated flight duration or distance between refueling bouts. Seasonal pre-migratory deposition of fat is well documented in regular seasonal migrants, but is less described for more facultative species. We analyze fat deposits of free-living birds across several taxa of facultative migrants in the songbird subfamily Carduelinae, including house finches (Haemorhous mexicanus), American goldfinches (Spinus tristis), pine siskins (Spinus pinus) and four different North American ecotypes of red crossbills (Loxia curvirostra), to evaluate seasonal fat deposition during facultative migratory periods. Our data suggest that the extent of seasonal fat deposits corresponds with migratory tendency in these facultative taxa. Specifically, nomadic red crossbills with a seasonally predictable annual movement demonstrated relatively large seasonal fat deposits coincident with the migratory periods. In contrast, pine siskins, thought to be more variable in timing and initiation of nomadic movements, had smaller peaks in fat deposits during the migratory season, and the partial migrant American goldfinch and the resident house finch showed no peaks coincident with migratory periods. Within the red crossbills, those ecotypes that are closely associated with pine habitats showed larger peaks in fat deposits coincident with autumn migratory periods and had higher wing loading, whereas those ecotypes associated with spruces, Douglas-fir and hemlocks showed larger peaks coincident with spring migratory periods and lower wing loading. We conclude that population averages of fat deposits do reflect facultative migration strategies in these species, as well as the winter thermogenic challenges at the study locations. A difference in seasonal fattening and wing loading among red crossbill ecotypes is consistent with the possibility that they differ in their migratory biology, and we discuss these differences in light of crossbill reproductive schedules and phenologies of different conifer species.