Engert Elana Rae, Hellström Magnus, Åkesson Susanne
Department of Biology, Centre for Animal Movement Research Lund University Lund Sweden.
Ottenby Bird Observatory BirdLife Sweden Ottenby Sweden.
Ecol Evol. 2023 Jan 16;13(1):e9571. doi: 10.1002/ece3.9571. eCollection 2023 Jan.
Songbirds have evolved diverse strategies to cope with seasonality, including long-, medium-, and short-distance migration. There is some evidence that birds with a longer migration distance deposit fuel faster. However, most studies focus on long-distance migrants. Comparisons between species with different migration distances are necessary to broaden our understanding of fueling capacity in migratory birds. We present maximum fuel deposition rates of five songbird species migrating along the southeast coast of Sweden in autumn with migration distances ranging from long (neotropical migrant) to short (partial/irruptive migrant) (Willow Warbler , Lesser Whitethroat , Common Chiffchaff , European Robin , and Blue Tit ). The birds were fed ad libitum in captivity and were exposed to either extended or natural daylength. All species ceased to increase in mass when they reached a certain fuel load, generally corresponding to migration distance, despite unlimited access to food and ample time for foraging. Blue Tits, Willow Warblers, and Lesser Whitethroats had the highest fuel deposition rates with extended daylength (19%, 20%, and 20%, respectively), and about 13% with natural daylength, which is comparable to the highest rates found in migratory songbirds in nature. European Robins and Common Chiffchaffs that winter in the temperate Mediterranean had the lowest fuel deposition rates (12% and 12% with extended daylength, respectively). Our results suggest that the long- and short-distance migrants in this study have developed an extreme capacity for rapid refueling for different reasons; speedy migration to distant wintering grounds or winter survival in Scandinavia. This study contributes to our current knowledge of maximum fuel deposition rates in different species and the limitations posed by daylength. We highlight the need for future studies of species with different migration strategies in order to draw broad conclusions about fueling strategies of migratory birds.
鸣禽已经进化出多种应对季节性变化的策略，包括长距离、中距离和短距离迁徙。有证据表明，迁徙距离较长的鸟类储存能量的速度更快。然而，大多数研究都集中在长距离迁徙的鸟类上。比较不同迁徙距离的物种，对于拓宽我们对候鸟能量储存能力的理解是必要的。我们展示了五种在秋季沿着瑞典东南海岸迁徙的鸣禽物种的最大能量储存率，它们的迁徙距离从长距离（新热带迁徙鸟类）到短距离（部分/爆发性迁徙鸟类）不等（柳莺、白斑尾柳莺、普通凤头䴓、欧亚鸲和青山雀）。这些鸟类在圈养环境中自由进食，并暴露在延长或自然日照长度下。尽管有无限的食物供应和充足的觅食时间，但所有物种在达到一定的能量负载时就停止增加体重，这通常与迁徙距离相对应。青山雀、柳莺和白斑尾柳莺在延长日照长度下的能量储存率最高（分别为19%、20%和20%），在自然日照长度下约为13%，这与自然界中迁徙鸣禽的最高能量储存率相当。在地中海温带地区越冬的欧亚鸲和普通凤头䴓的能量储存率最低（延长日照长度下分别为12%）。我们的研究结果表明，本研究中的长距离和短距离迁徙鸟类出于不同原因已经发展出了极端的快速补充能量的能力；快速迁徙到遥远的越冬地或在斯堪的纳维亚半岛度过冬季。这项研究有助于我们目前对不同物种最大能量储存率以及日照长度所带来的限制的了解。我们强调，未来需要对具有不同迁徙策略的物种进行研究，以便对候鸟的能量补充策略得出广泛的结论。
