Billions of birds migrate over North America throughout the spring and fall. They may use landmarks, the stars, or the earth’s magnetic field to get to their destinations. That last navigation aid is impacted by the northern lights, which involve particles from solar eruptions interacting with gases in our atmosphere. While these displays leave us in awe, they may also leave migrating birds a bit discombobulated.

A 2023 study published in Proceedings of the National Academy of Sciences looked at Doppler radar and magnetometers to see whether severe solar storms impacted the number of birds migrating at night, the amount of effort they put into flying against the wind, and flight altitude. In all, the research involved 1.7 million radar scans from fall and 1.4 million from spring, across more than 20 years over the Great Plains.

The findings show the northern lights may throw a wrench into birds’ nocturnal migration plans.

Eric Gulson-Castillo, first author who undertook this research as part of his doctoral dissertation at the University of Michigan, explains, “Our results suggest that fewer birds migrate during strong geomagnetic disturbances and that migrating birds may experience more difficulty navigating, especially under overcast conditions in autumn. As a result, they may spend less effort actively navigating in flight and consequently fly in greater alignment with the wind.”

So how many birds remained grounded during these severe solar storms? The study found that, when controlling for possible contributing factors, 9 to 17% fewer birds took to the skies during spring and fall storms. For those that did venture out, they put in lower effort while flying against the wind in the fall, which may mean they shifted to drifting with the wind. This decrease in effort was up to 25% when it was overcast, as well, suggesting that not being able to use the stars may make things even more problematic in those conditions.

The authors write, “We found that an interaction between cloud cover and geomagnetic disturbance did not affect migration intensity and was apparently only important for one variable, the crosswind component in the fall. These results suggest that the decision to migrate or not during geomagnetic disturbances is not generally affected by the ability to see celestial cues, but that navigation might be impaired under those conditions if birds decide to migrate.”

The team says that longer-term impacts to the Earth’s magnetic field could also impact bird migration, and better migration monitoring technology could help scientists better understand the link between space weather and birds’ biological systems.

If you’d like to do your part to help migrating birds, learn how here!