Upcoming solar maximum could scramble migrating birds' internal compass, new study shows

Migratory birds in the U.S. struggle to properly navigate when solar storms and other types of space weather disrupt their ability to sense Earth's magnetic field, a new study shows. The findings suggest that these birds may be seriously handicapped over the next few years as the sun ramps up toward its explosive peak — the solar maximum.

The sun regularly spits out bursts of high-energy particles and radiation, such as coronal mass ejections (CMEs), or strong gusts of solar wind. When those outbursts slam into Earth, they can cause temporary fluctuations in the planet's magnetic shield, or magnetosphere. Scientists already knew these geomagnetic disturbances interfere with other Animals' magnetoreception, or ability to sense the magnetosphere.

In the study, which was published Oct. 9 in the journal Proceedings of the National Academy of Sciences, researchers studied the migratory patterns of a wide range of nocturnal migratory birds over a 23-year period. This included perching birds, like thrushes and warblers; shorebirds, such as sandpipers and plovers; and waterfowl such as ducks and geese. 

The team analyzed more than 3 million radar images to track how the birds moved across the central flyway of the U.S. Great Plains — a major migratory corridor that spans more than 1,000 miles (1,610 kilometers) between Texas and North Dakota. Using magnetic field data collected by instruments on the ground during the same period, the researchers were able to see if the avians' behavior changed during geomagnetic disturbances. 

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After analyzing the data, the team discovered that during geomagnetic disturbances, there was a 9% to 17% decrease in the number of birds attempting to migrate. The birds that did migrate during disturbances had more trouble correctly navigating their normal routes, researchers wrote in a statement.

"Our results suggest that fewer birds migrate during strong geomagnetic disturbances and that migrating birds may experience more difficulty navigating," study lead author Eric Gulson-Castillo, a doctoral candidate at the University of Michigan, said in the statement. This was most apparent during autumn, he added.