Previously, two studies have provided evidence that bats can use magnetic field cues for homing or roosting. For insectivorous bats, it is well established that foraging represents one of the most fundamental behaviors in animals relies on their ability to echolocate. Whether echolocating bats can also use magnetic cues during foraging remains unknown, however. Here, we tested the orientation behavior of Chinese noctules (Nyctalus plancyi) during foraging in a plus-shaped, 4-channel apparatus under different magnetic field conditions. To minimize the effects of spatial memory on orientation from repeated experiments, naïve bats were tested only once in each experimental condition. As expected, under geomagnetic field and a food resource offered conditions, the bats significantly preferred to enter the channel containing food, indicating that they primarily relied on direct sensory signals unrelated to magnetic cues. In contrast, when we offered food simultaneously in all four channels and minimized any differences in all other sensory signals available, the bats exhibited a clear directional preference to forage along the magnetic field direction under either geomagnetic field or a magnetic field in which the horizontal component was rotated by 90°. Our study offers a novel evidence for the importance of a geomagnetic field during foraging.
Geomagnetic field Bats Foraging orientation A plus-shaped channel apparatus Magnetic orientation
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We would like to thank Dr. Wei Lin for helpful discussions. This study was funded by the National Natural Science Foundation of China (Grant Numbers 41674071, 41621004) and the Chinese Academy of Sciences project (QYZDJ-SSW-DQC024).
LT, WM, and YP conceived the experiments and wrote the paper; BZ and JZ collected the animals and performed the experiments; HQ adjusted the experimental magnetic fields; and TZ and YC analyzed the behavioral data. All authors reviewed the manuscript and approved the final version submitted.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
The Ethics Committee of the Chinese Academy of Sciences on Vertebrate Animals Experiments and the Institute of Geology and Geophysics Administrative Panel on Animal Care approved all experimental procedures. The collection of the bats was approved by the Institute of Geology and Geophysics, Chinese Academy of Sciences.
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