Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
Curr Biol. 2017 Nov 6;27(21):R1152-R1153. doi: 10.1016/j.cub.2017.09.009.
Wildlife migration is a spectacular phenomenon [1]. Studies using telemetry - tracking devices attached on free-living animals - have shown that large topographic barriers and obstacles, such as oceans and deserts, elicit extreme feats of migration [2]. Overcoming the challenges of these obstacles might require experience and skill that young individuals lack [2-5]. Further, younger, inexperienced animals might determine their migration routes using navigation strategies different from those of older animals [6-9], but our knowledge of how orientation mechanisms and experience drive migration strategy is limited. We have studied how experienced (adults) and inexperienced (first-time migrating fledglings) streaked shearwaters (Calonectris leucomelas) approach the challenge of migration using animal-borne tracking devices. The study birds migrate from a colony on the north of a large topographic barrier, Honshu Island, Japan. Shearwaters use a wind- and wave-based flight pattern-dynamic soaring-to extract energy for highly efficient travel over oceans [10]. We therefore expected that shearwaters migrating southward from the colony would make substantial detours to avoid any landmasses. We found that migrating adults followed one of two paths that detour around landmasses that hinder direct southerly migration. In contrast, inexperienced fledglings followed a straight course in a south-oriented direction that forced them to complete a trans-mountain journey, suggesting that the birds rely on an innate compass. Thus, we suggest that fledglings would eventually override the simple compass navigation, which appears to be the primary driver for their extreme migration, before being able to interact appropriately with the marine environment.
野生动物迁徙是一种壮观的现象[1]。使用追踪设备（附着在自由生活的动物上的遥测设备）进行的研究表明，大型地形障碍和障碍物，如海洋和沙漠，引发了极端的迁徙壮举[2]。克服这些障碍物的挑战可能需要年轻个体缺乏的经验和技能[2-5]。此外，年轻、缺乏经验的动物可能会使用与年长动物不同的导航策略来确定它们的迁徙路线[6-9]，但我们对定向机制和经验如何驱动迁徙策略的了解是有限的。我们研究了经验丰富的（成年）和缺乏经验的（首次迁徙的幼鸟）条纹燕鸥（Calonectris leucomelas）如何使用动物携带的跟踪设备来应对迁徙的挑战。研究鸟类从日本本州岛北部的一个大的地形障碍上的一个繁殖地迁徙。燕鸥使用一种基于风和波浪的飞行模式——动态翱翔——来提取能量，以在海洋上进行高效的长途飞行[10]。因此，我们预计从繁殖地向南迁徙的燕鸥会大幅度绕路，以避开任何陆地。我们发现，成年迁徙者沿着两条路线中的一条绕开了阻碍直接向南方迁徙的陆地。相比之下，缺乏经验的幼鸟则沿着一个向南的直线方向前进，这迫使它们完成一次跨山的旅程，这表明鸟类依赖于一种内在的罗盘。因此，我们认为，幼鸟在能够与海洋环境适当互动之前，最终会克服简单的罗盘导航，这似乎是它们极端迁徙的主要驱动力。
