Centre for Animal Movement Research, Department of Biology, Lund University, Ecology Building, 223 62, Lund, Sweden.
Max Planck Institute for Terrestrial Microbiology, 35043, Marburg, Germany.
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2022 Jan;208(1):135-144. doi: 10.1007/s00359-021-01536-9. Epub 2022 Jan 7.
Spontaneous magnetic alignment is the simplest known directional response to the geomagnetic field that animals perform. Magnetic alignment is not a goal directed response and its relevance in the context of orientation and navigation has received little attention. Migratory songbirds, long-standing model organisms for studying magnetosensation, have recently been reported to align their body with the geomagnetic field. To explore whether the magnetic alignment behaviour in songbirds is involved in the underlying mechanism for compass calibration, which have been suggested to occur near to sunset, we studied juvenile Eurasian reed warblers (Acrocephalus scirpaceus) captured at stopover during their first autumn migration. We kept one group of birds in local daylight conditions and an experimental group under a 2 h delayed sunset. We used an ad hoc machine learning algorithm to track the birds' body alignment over a 2-week period. Our results show that magnetic body alignment occurs prior to sunset, but shifts to a more northeast-southwest alignment afterwards. Our findings support the hypothesis that body alignment could be associated with how directional celestial and magnetic cues are integrated in the compass of migratory birds.
自发的磁场定向是动物对地球磁场表现出的最简单的定向反应。磁场定向不是一种有目的的反应，其在定向和导航中的相关性很少受到关注。候鸟作为研究磁感觉的长期模式生物，最近被报道会使它们的身体与地磁场对齐。为了探讨鸟类的磁场定向行为是否参与了被认为发生在日落后的罗盘校准的潜在机制，我们研究了在第一次秋季迁徙中中途停留的幼年欧亚芦苇莺（Acrocephalus scirpaceus）。我们将一组鸟类保持在当地的日光条件下，而实验组则延迟日落 2 小时。我们使用一个专门的机器学习算法在两周的时间内跟踪鸟类的身体对齐情况。我们的结果表明，磁场定向发生在日落之前，但之后会转向更东北-西南方向的对齐。我们的发现支持这样的假设，即身体定向可能与候鸟的罗盘如何整合天向和磁线索有关。
