Herring Gulls (Larus Argentatus); Ronconi; Sable 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.背景：近期研究指出，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压缩迁徙耗时，以应对环境条件的季节性变化。方法：本研究针对觅食与飞行行为具有灵活性的广适性物种——银鸥（Herring Gulls, Larus argentatus）的迁徙策略变异性展开评估。我们追踪了1个长途迁徙种群与3个短途迁徙种群，对比分析了其迁徙路线的直航性、整体迁徙速度、行进速度以及中途停留地的使用情况。结果：本研究显示，在东极地区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4倍以上。尽管所有种群均采用迂回迁徙路线，但长途迁徙种群的路线直达性最差。研究发现，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飞行速度更高。虽然长途迁徙种群的总停留天数更多，但相较于各自的迁徙总距离，4个种群的中途停留天数并无显著差异。结论：结合其他相关研究的背景来看，我们认为，诸如银鸥这类具备行为灵活性的广适性物种，其迁徙策略受栖息地与食物资源的影响程度或大于迁徙距离本身。