Space Storms Have Weird Effect on Birds, Scientists Discover

Geomagnetic storms can have some weird and wonderful impacts on the Earth, ranging from the spectacular northern lights to radio blackouts, but they can also affect an unexpected part of nature: birds.

Scientists have found that migratory birds across the world stay on the ground during space weather events when they would normally be flying, due to the effects that geomagnetic storms have on their ability to navigate using the Earth's magnetic field.

The number of migrating birds flying was found to decrease by between 9 and 17 percent during severe space weather events, and those that did fly experienced difficulty in finding their way to their destination, a new study in the journal Proceedings of the National Academy of Sciences has revealed.

"Birds and other animals are well known to use the Earth's magnetic field to orient (determine which direction to fly in) and likely also to navigate," study co-author Ben Winger told Newsweek.

"They likely cue in to geographic variation in the inclination and intensity of the magnetic field. This has mostly been studied in pigeons and in small songbirds, but it is thought that many kinds of birds have this ability."

Winger is an assistant professor in the University of Michigan's Department of Ecology and Evolutionary Biology, and a curator of birds at the University of Michigan Museum of Zoology.

Geomagnetic storms are alterations of the Earth's magnetic fields, caused by solar flares or coronal mass ejections of solar plasma from the sun. These interact with electrons in the Earth's magnetosphere, altering electromagnetic charge and causing auroras and other effects across the globe. These alterations can also impact the navigation of animals that use the magnetic field to find their way, such as birds.

The researchers made this discovery after comparing bird activity from a 23-year dataset of bird migration across the Great Plains, and space weather events from large long-term datasets from networks of U.S. Doppler weather radar stations and ground-based instruments measuring magnetism.

"Our study suggests that fewer birds migrate during large geomagnetic storms," Winger said. "Our results also suggest that in certain conditions, birds that do migrate during geomagnetic storms may have more difficulty navigating, but we only found evidence for this pattern in fall migration and during high cloud cover, when birds might not be able to use celestial navigational cues."

The research also found that birds that did fly found it harder to navigate during space weather events, especially when conditions were overcast.

"Our study cannot specifically speak to birds getting lost as our methods (radar monitoring) do not allow us to track individual birds," Winger said. "However, a separate recent study from earlier this year found evidence that migratory birds likely do get lost in some of the same geomagnetic conditions affecting the birds in our dataset."

This is likely because migratory birds mostly travel during the night, using the stars and night sky as well as the magnetic field to orient themselves.

"For our study, we focused on birds that migrate at night. Most birds, especially songbirds, only migrate at night, it is thought this is because there is a lower predation risk and it is more energetically efficient," Eric Gulson-Castillo, lead author of the paper, told Newsweek.

Gulson-Castillo is a doctoral student in the University of Michigan's Department of Ecology and Evolutionary Biology.

"Birds are likely using a suite of navigation cues to increase the accuracy of their migrations. This includes the magnetic field and the different aspects of the magnetic field that Ben [Winger] mentioned, but also the rotation of the stars—they learn that the north star points northwards, for example—and visual cues such as coastlines and mountain ranges. So birds use magnetic fields as part of their migration 'toolkit.'"

Additionally, they found that during these storms, birds were more likely to drift with the wind rather than battle against it to go in a certain direction, known as "effort flying." This was seen to drop by 25 percent when a geomagnetic storm was occurring combined with overcast conditions.

"Our results do suggest that when birds have more difficulty navigating, they might drift with the wind more often, as we specifically measured that they show less resistance to the wind in the fall under overcast conditions," Gulson-Castillo said.

"I agree with Ben that this is not direct evidence for birds getting lost, which is what [previous papers] measured, but one of our interpretations of this result is that birds could get lost more often if they drift more with the wind. Overall, we think this is an interesting question that will benefit from more research."

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