Solar explosions could be confusing for migrating birds
Birds might find migration to and from Texas next year to be more arduous, thanks to heightened activity from the sun that can disrupt Earth’s magnetic fields, which they use to navigate.
A recent study examining migration from Texas to North Dakota found that birds were less likely to take off for their evening flight – or were more likely to be blown off course – during intense periods of “space weather” caused by the sun.
And with the sun entering its period of peak activity in 2024, birds might have to rely on stars, mountain ranges, coastlines and other alternative navigation cues, said Eric Gulson-Castillo, a doctoral student in the University of Michigan’s department of ecology and evolutionary biology. “Or they might find themselves grounded more often.”
The sun’s peak activity will create more sunspots, locations where giant explosions can thrust pieces of the sun’s plasma and associated magnetic field energy into space. The ejected material travels toward Earth and disrupts the magnetic fields that birds use to distinguish north from south, GulsonCastillo said. The sun’s activity is expected to peak between January and October and is part of an 11year cycle. This peak is expected to be weaker than average but greater than the most recent one in April 2014, according to the National Oceanic and or lost
Atmospheric Administration’s Space Weather Prediction Center.
Previous studies have shown that birds use Earth’s magnetic field to migrate. In most of them, researchers temporarily kept birds in captivity and placed them in funnelshaped cages for behavioral orientation tests. Researchers changed the magnetic field around the cage and watched as birds changed the direction they were hopping and fluttering (their would-be migration).
But there haven’t been many studies in the wild, especially not with access to large data sources. Gulson-Castillo — lead author on the study published in October in the Proceedings of the National Academy of Sciences – and his collaborators realized they could monitor birds across the U.S. by comparing two massive sets of data: weather radar that detects bird migration and magnetometers that provide minute-by-minute measurements of Earth’s magnetic field.
Gulson-Castillo and his fellow researchers compared deviations from the expected magnetic field data with the weather radar and detected a 9% to 17% drop in birds migrating during times of severe space weather. The group studied data that goes back 20 years and spans more than 1,000 miles across the United States.
He said the drop in migrating birds could be a precaution on their part: Perhaps they choose not to fly because they can sense the change in the magnetic field.
And for those that did fly, the radar data showed the birds spent 25% less of their energy fighting the wind.
Researchers see it as a sign that the birds were more willing to let the wind take them rather than fighting it to reach a specific destination when the weather was overcast and there was severe space weather.
Gulson-Castillo, an ornithologist, said the study will help researchers understand the sensory abilities of birds and the challenges they experience during migration as their numbers dwindle.
“My study is not necessarily going to shed light on a new aspect of bird conservation,” he said. “But it is shedding light on this sort of bigger system that we do want to understand because a lot of these birds are declining on a more global scale.”