Magnetic storms disrupt nocturnal migratory activity in songbirds
To address this question, the researchers reproduced the effect of a solar storm on the geomagnetic field and monitored the activity of three songbird species (European robins, chiffchaffs and dunnocks) during autumn migration.
All three species kept a well-defined daily activity schedule with higher activity at night for the nocturnally migrating chiffchaff and robin, and higher activity during morning for the diurnally migrating dunnock. However, the study showed that only one of the two tested nocturnal migrants, the European robin, changed its activity level in response to the simulated solar storm. The changes were detected at night, when robins reduced activity, and during the morning, when they increased their activity. The authors propose that the reduced activity at night was used to reduce the orientation and/or navigation errors that may accumulate during migration in a disturbed magnetic field, and may have been performed as an energy-saving strategy to be able to extend the migratory schedule during the day. In daytime, alternative navigation cues become available, and any cue conflict involving the magnetic compass could be more easily resolved.
The other two species, chiffchaff and dunnock, showing low or no nocturnal migratory activity, did not respond to the solar storm by changing activity.
To the paper, Magnetic storm disrupts nocturnal migratory activity in songbirds, in Biology Letters.