Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, 16521 Praha 6, Czech Republic.
Department of General Zoology, Faculty of Biology, University of Duisburg-Essen, 45117 Essen, Germany.
Front Zool. 2013 Dec 27;10(1):80. doi: 10.1186/1742-9994-10-80.
Several mammalian species spontaneously align their body axis with respect to the Earth's magnetic field (MF) lines in diverse behavioral contexts. Magnetic alignment is a suitable paradigm to scan for the occurrence of magnetosensitivity across animal taxa with the heuristic potential to contribute to the understanding of the mechanism of magnetoreception and identify further functions of magnetosensation apart from navigation. With this in mind we searched for signs of magnetic alignment in dogs. We measured the direction of the body axis in 70 dogs of 37 breeds during defecation (1,893 observations) and urination (5,582 observations) over a two-year period. After complete sampling, we sorted the data according to the geomagnetic conditions prevailing during the respective sampling periods. Relative declination and intensity changes of the MF during the respective dog walks were calculated from daily magnetograms. Directional preferences of dogs under different MF conditions were analyzed and tested by means of circular statistics.
Dogs preferred to excrete with the body being aligned along the North-South axis under calm MF conditions. This directional behavior was abolished under unstable MF. The best predictor of the behavioral switch was the rate of change in declination, i.e., polar orientation of the MF.
It is for the first time that (a) magnetic sensitivity was proved in dogs, (b) a measurable, predictable behavioral reaction upon natural MF fluctuations could be unambiguously proven in a mammal, and (c) high sensitivity to small changes in polarity, rather than in intensity, of MF was identified as biologically meaningful. Our findings open new horizons in magnetoreception research. Since the MF is calm in only about 20% of the daylight period, our findings might provide an explanation why many magnetoreception experiments were hardly replicable and why directional values of records in diverse observations are frequently compromised by scatter.
在不同的行为背景下，几种哺乳动物会自发地使身体轴与地球磁场（MF）线对齐。磁对齐是一种合适的范例，可以扫描动物分类群中磁敏感性的发生，具有启发潜力，可以帮助理解磁受体的机制，并确定除导航以外的磁感觉的其他功能。考虑到这一点，我们在狗中寻找磁对齐的迹象。我们在两年的时间里，在 70 只 37 个品种的狗在排便（1893 次观察）和排尿（5582 次观察）期间测量了身体轴的方向。在完成采样后，我们根据在各自采样期间占主导地位的地磁条件对数据进行了分类。从每日地磁图中计算出 MF 在各自狗行走期间的相对赤纬和强度变化。通过循环统计分析，分析并测试了狗在不同 MF 条件下的方向偏好。
在平静的 MF 条件下，狗更倾向于将身体沿着南北轴排泄。这种定向行为在不稳定的 MF 下被废除。行为转变的最佳预测指标是赤纬的变化率，即 MF 的极向。
这是第一次（a）在狗中证明了磁性敏感性，（b）在哺乳动物中可以明确证明对自然 MF 波动的可测量、可预测的行为反应，（c）对 MF 极性变化的高敏感性，而不是强度变化，被确定为具有生物学意义。我们的发现为磁受体研究开辟了新的视野。由于 MF 在白天只有大约 20%的时间是平静的，我们的发现可能解释了为什么许多磁受体实验几乎无法复制，以及为什么在不同观察中记录的方向值经常因分散而受到影响。
