Herring Gulls (Larus Argentatus); Ronconi; Kent Island Canada-argos

Background: Recent studies have proposed that birds migrating short distances migrate at an overall slower pace, minimizing energy expenditure, while birds migrating long distances minimize time spent on migration to cope with seasonal changes in environmental conditions. Methods: We evaluated variability in the migration strategies of Herring Gulls (Larus argentatus), a generalist species with flexible foraging and flight behaviour. We tracked one population of long distance migrants and three populations of short distance migrants, and compared the directness of their migration routes, their overall migration speed, their travel speed, and their use of stopovers. Results: Our research revealed that Herring Gulls breeding in the eastern Arctic migrate long distances to spend the winter in the Gulf of Mexico, traveling more than four times farther than gulls from Atlantic Canada during autumn migration. While all populations used indirect routes, the long distance migrants were the least direct. We found that regardless of the distance the population traveled, Herring Gulls migrated at a slower overall migration speed than predicted by Optimal Migration Theory, but the long distance migrants had higher speeds on travel days. While long distance migrants used more stopover days overall, relative to the distance travelled all four populations used a similar number of stopover days. Conclusions: When taken in context with other studies, we expect that the migration strategies of flexible generalist species like Herring Gulls may be more influenced by habitat and food resources than migration distance.

研究背景：近期已有研究提出，短途迁徙鸟类整体迁徙节奏更为缓慢，以最小化能量消耗；而长途迁徙鸟类则会尽可能缩短迁徙耗时，以应对环境条件的季节性变化。
研究方法：本研究针对具备灵活觅食与飞行行为的广食性物种银鸥（Herring Gulls，Larus argentatus）的迁徙策略差异展开评估。我们对1个长途迁徙种群及3个短途迁徙种群开展了追踪监测，并对比了其迁徙路线的直线性、整体迁徙速度、行进速度以及停歇位点的利用情况。
研究结果：本研究发现，在北极东部繁殖的银鸥会长途迁徙至墨西哥湾越冬，其秋季迁徙的飞行距离是加拿大大西洋沿岸银鸥的四倍以上。尽管所有种群均采用迂回路线，但长途迁徙种群的路线直线性最差。研究表明，无论种群迁徙距离长短，银鸥的整体迁徙速度均低于最优迁徙理论（Optimal Migration Theory）的预测值，但长途迁徙种群在行进日的速度更快。尽管长途迁徙种群的总停歇天数更多，但按迁徙距离折算后，四个种群的停歇天数并无显著差异。
研究结论：综合现有相关研究来看，我们认为诸如银鸥这类具备灵活习性的广食性物种，其迁徙策略受栖息地与食物资源的影响程度，可能大于迁徙距离本身的影响。