Martini Sabine, Begall Sabine, Findeklee Tanja, Schmitt Marcus, Malkemper E Pascal, Burda Hynek
Department of General Zoology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany.
Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Prague, Czech Republic.
PeerJ. 2018 Dec 17;6:e6117. doi: 10.7717/peerj.6117. eCollection 2018.
Magnetoreception, the ability to sense the Earth's magnetic field (MF), is a widespread phenomenon in the animal kingdom. In 1966, the first report on a magnetosensitive vertebrate, the European robin (), was published. After that, numerous further species of different taxa have been identified to be magnetosensitive as well. Recently, it has been demonstrated that domestic dogs () prefer to align their body axis along the North-South axis during territorial marking under calm MF conditions and that they abandon this preference when the Earth's MF is unstable. In a further study conducting a directional two-choice-test, dogs showed a spontaneous preference for the northern direction. Being designated as putatively magnetosensitive and being also known as trainable for diverse choice and search tests, dogs seem to be suitable model animals for a direct test of magnetoreception: learning to find a magnet. Using operant conditioning dogs were trained to identify the MF of a bar magnet in a three-alternative forced-choice experiment. We excluded visual cues and used control trials with food treats to test for the role of olfaction in finding the magnet. While 13 out of 16 dogs detected the magnet significantly above chance level (53-73% success rate), none of the dogs managed to do so in finding the food treat (23-40% success rate). In a replication of the experiment under strictly blinded conditions five out of six dogs detected the magnet above chance level (53-63% success rate). These experiments support the existence of a magnetic sense in domestic dogs. Whether the sense enables dogs to perceive MFs as weak as the Earth's MF, if they use it for orientation, and by which mechanism the fields are perceived remain open questions.
磁感受，即感知地球磁场（MF）的能力，是动物界普遍存在的现象。1966年，关于一种磁敏感脊椎动物——欧洲知更鸟（Erithacus rubecula）的首份报告发表。此后，又有许多不同分类群的物种被鉴定为具有磁敏感性。最近有研究表明，家养犬（Canis lupus familiaris）在平静的磁场条件下进行领地标记时，更喜欢将身体轴线沿南北轴线排列，而当地球磁场不稳定时，它们会放弃这种偏好。在另一项进行定向二选一测试的研究中，狗表现出对北方方向的自发偏好。由于被假定具有磁敏感性，并且在各种选择和搜索测试中也具有可训练性，狗似乎是直接测试磁感受的合适模式动物：学习找到一块磁铁。在一项三选一强制选择实验中，利用操作性条件反射训练狗识别条形磁铁的磁场。我们排除了视觉线索，并使用食物奖励的对照试验来测试嗅觉在寻找磁铁中的作用。16只狗中有13只检测到磁铁的成功率显著高于随机水平（成功率为53%-73%），而在寻找食物奖励时，没有一只狗能够做到这一点（成功率为23%-40%）。在严格盲视条件下重复该实验时，6只狗中有5只检测到磁铁的成功率高于随机水平（成功率为53%-63%）。这些实验支持了家养犬存在磁感的观点。这种感觉是否能使狗感知到与地球磁场一样微弱的磁场，它们是否利用它来定向，以及通过何种机制感知磁场，这些仍然是悬而未决的问题。
