Data from: The geomagnetic environment in which sea turtle eggs incubate affects subsequent magnetic navigation behavior of hatchlings

Loggerhead sea turtle hatchlings (Caretta caretta) use regional magnetic fields as open-ocean navigational markers during trans-oceanic migrations. Little is known, however, about the ontogeny of this behaviour. As a first step towards investigating whether the magnetic environment in which hatchlings develop affects subsequent magnetic orientation behaviour, eggs deposited by nesting female loggerheads were permitted to develop in situ either in the natural ambient magnetic field or in a magnetic field distorted by magnets placed around the nest. In orientation experiments, hatchlings that developed in the normal ambient field oriented approximately south when exposed to a field that exists near the northern coast of Portugal, a direction consistent with their migratory route in the northeastern Atlantic. By contrast, hatchlings that developed in a distorted magnetic field had orientation indistinguishable from random when tested in the same north Portugal field. No differences existed between the two groups in orientation assays involving responses to orbital movements of waves or sea-finding, neither of which involves magnetic field perception. These findings, to our knowledge, demonstrate for the first time that the magnetic environment present during early development can influence the magnetic orientation behaviour of a neonatal migratory animal.

蠵龟（Loggerhead sea turtle，Caretta caretta）幼龟在跨洋迁徙过程中，会利用区域磁场作为开阔海洋的导航标识。然而，学界对该行为的个体发生过程尚知之甚少。为探究幼龟发育所处的磁场环境是否会影响其后续的磁场定向行为，研究人员将筑巢雌性蠵龟所产的卵，分别置于天然环境磁场，或是巢周放置磁铁所畸变的磁场中进行原位发育。定向实验结果显示，在正常环境磁场中发育的幼龟，当暴露于葡萄牙北海岸附近存在的磁场时，其朝向大致为南向，该方向与它们在东北大西洋的迁徙路线相符。相较之下，在畸变磁场中发育的幼龟，在同一葡萄牙北部磁场环境下接受测试时，其定向表现与随机选择无显著差异。在涉及对波浪轨道运动反应或趋海行为的定向测试中，两组幼龟未表现出显著差异——这两类测试均不涉及磁场感知。据我们所知，本研究首次证实，早期发育阶段所处的磁场环境，能够影响新生洄游动物的磁场定向行为。