Research into the patterns and drivers of juvenile migration is important for understanding the development of individual migration strategies. Although several recent studies have tracked adult large gulls throughout the annual cycle, the movements of juveniles remain poorly understood. We fitted Global Positioning System (GPS) devices that transmit locations through the Global System for Mobile Communications (GSM) to ten juvenile Lesser Black-backed Gulls Larus fuscus prior to fledging on the island of Spiekeroog, Germany, to study their first autumn migration and wintering behaviour. The tracked birds initially departed on similar compass bearings south to south-west, after which migration routes diverged. Individuals took 38–107 days to reach their wintering sites in Algeria, Morocco or Spain. Birds visited 6.7 ± 3.7 (mean ± sd) stopover sites en route and spent substantial time in northern Europe, with some individuals converging at the same sites over small spatial scales (<1 km), but not over the same time periods. Birds increased travel speeds in the second half of their migration. They showed relatively high site-fidelity after arrival at wintering sites, and there was no evidence that the size of foraging areas increased over time, suggesting limited exploratory behaviour. Individuals used the same predominant habitats – cropland, open water and built-up areas – to varying degrees, but showed limited variation in habitat use over time. Overall, the migration routes and timings of juveniles broadly resembled those of previously tracked adults. Given their similar initial bearings and abundance of large gulls on the flyway, we suggest that social learning is likely to be an important process shaping the individual migration and wintering strategies of juvenile gulls.

中文翻译：

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小黑背鸥（Larus fuscus）个体幼鸟的后迁徙和越冬策略

研究青少年移民的模式和驱动因素对于理解个人移民策略的发展很重要。尽管最近的几项研究在整个年度周期中追踪了成年大海鸥，但对幼海鸥的活动仍知之甚少。我们安装了全球定位系统 (GPS) 设备，通过全球移动通信系统 (GSM) 向十只幼年小黑背鸥Larus fuscus传输位置在前往德国 Spiekeroog 岛之前，研究它们的第一次秋季迁徙和越冬行为。被追踪的鸟类最初从南到西南的类似罗盘方位出发，之后迁徙路线分道扬镳。个体需要 38-107 天才能到达他们在阿尔及利亚、摩洛哥或西班牙的越冬地点。鸟类在途中访问了 6.7 ± 3.7（平均值 ± sd）中途停留地点并在北欧度过了大量时间，一些人在小空间尺度（<1 公里）内聚集在相同的地点，但不是在同一时间段内。鸟类在迁徙的后半段提高了旅行速度。它们在到达越冬地点后表现出相对较高的地点保真度，并且没有证据表明觅食区的规模随着时间的推移而增加，这表明探索行为有限。个体在不同程度上使用相同的主要栖息地——农田、开阔水域和建成区——但随着时间的推移，栖息地使用的变化有限。总体而言，幼鱼的迁徙路线和时间与之前追踪的成鱼大体相似。鉴于它们相似的初始方位和飞行路线上大量的大型海鸥，