Most activities of Weddell seals (Leptonychotes weddellii) occur during under-ice dives that extend hundreds to thousands of meters and require the seals to hold their breath for 15 min or more. In the fast-ice environment of Antarctica, holes in the ice where seals can surface to breathe are scarce. Consequently, seals must return to a previous breathing hole or locate a new one to avoid drowning; how they navigate underwater with such precision is not known. This study individually displaced ten seals, each fitted with an archival data logger, to unfamiliar locations and analyzed the three dimensional paths of voluntary dives to test eight predictions under four hypothesized way-finding tactics: geomagnetic sensitivity, path integration, pilotage, and hydrodynamic trail following. Analyses of dive tracks provided strong evidence that Weddell seals primarily used pilotage via visible, overhead features to return home during individual dives under ice cover. Upon release at an unfamiliar location, long-distance diving began only after a period of short-distance diving. Outbound paths of dives progressively increased in distance from home. Homeward paths were remarkably straight and oriented directly toward home, or they traveled to a frequented route then turned toward home. Seventy-five percent of the frequented routes were directly below known linear disturbances in the snow on the top of the sea ice. There was little evidence that seals used geomagnetic or hydrodynamic cues, nor that homing ability was hindered by low light levels (twilight). These results contribute to a growing body of literature indicating that animals can learn to use artificial, and sometimes ephemeral landmarks to guide their movements. How Weddell seals are able to dive during polar winter, with only starlight and moonlight to illuminate landmarks, remains unknown.

中文翻译：

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南极快冰环境下威德尔海豹的归巢策略

威德尔海豹 (Leptonychotes weddellii) 的大多数活动发生在冰下潜水期间，潜水范围延伸数百至数千米，需要海豹屏住呼吸 15 分钟或更长时间。在南极洲的快冰环境中，海豹可以浮出水面呼吸的冰洞很少。因此，海豹必须返回先前的呼吸孔或找到新的呼吸孔以避免溺水；他们如何以如此精确的方式在水下航行尚不清楚。这项研究将 10 只海豹分别安置到不熟悉的位置，每只海豹都配有档案数据记录器，并分析了自愿潜水的三维路径，以在四种假设的寻路策略下测试八种预测：地磁敏感性、路径整合、引航和水动力轨迹下列的。对潜水路线的分析提供了强有力的证据，表明威德尔海豹主要通过可见的、头顶的特征进行引航，以便在冰盖下进行个人潜水时返回家园。在陌生的地方释放后，只有在短距离潜水一段时间后才开始长距离潜水。随着离家的距离越来越远，潜水的出站路径逐渐增加。回家的路径非常笔直，直接指向家，或者他们走一条经常光顾的路线，然后转向家。75% 的常去路线直接位于海冰顶部雪中已知的线性扰动之下。几乎没有证据表明海豹使用地磁或流体动力学线索，也没有低光照水平（暮光）阻碍其归巢能力。这些结果有助于越来越多的文献表明动物可以学会使用人工的、有时是短暂的地标来引导它们的运动。威德尔海豹如何在极地冬季潜水，只有星光和月光照亮地标，仍然未知。