Solar storms may affect the navigation sense of California gray whales, researchers report.
Many animals can sense the Earth’s magnetic field and use it like a GPS to navigate during their long migrations. However, solar storms could be disrupting that signal, says Jesse Granger, a biophysics graduate student who studies in the lab of Sönke Johnsen, a biology student at Duke University.
Earlier research found a correlation between solar activity like sunspots and flares and stranded sperm whales, but the new analysis tried to get to the bottom of exactly what the relationship might be.
Gray whales (Eschrichtius robustus) are an ideal species to test this idea because they migrate 10,000 miles a year from Baja California to Alaska and back and stay relatively close to the shore, where small navigational errors could lead to disaster, Granger says.
She compiled a NOAA database of gray whale stranding incidents over a period of 31 years and sifted out all the cases in which the whales were obviously sick, malnourished, injured, or entangled, leaving only 186 strandings of otherwise healthy animals.
Comparing the healthy strandings data to a record of solar activity and statistically sifting out several other possible factors like seasons, weather, ocean temperatures, and food abundance, Granger concluded that gray whales were 4.3 times more likely to strand when a lot of radio frequency noise from a solar outburst was hitting the Earth.
She suspects the issue isn’t that a solar storm warps the Earth’s magnetic field, though it can. It’s that the radio frequency noise created by the solar outburst does something to overwhelm the whales’ senses, preventing them from navigating altogether—as if turning their GPS off in the middle of the trip.
The likelihood that whales might be somehow tapping into the planet’s geomagnetic fields is pretty strong because landmarks are few in the open ocean, but unfortunately, researchers don’t yet know precisely how they navigate, Granger says.
While the findings provide more evidence for a magnetic sense, Granger says the whales may still be using other cues to make their migration. “A correlation with solar radio noise is really interesting, because we know that radio noise can disrupt an animal’s ability to use magnetic information.
“We’re not trying to say this is the only cause of strandings. It’s just one possible cause,” she says.
The study appears in Current Biology.
Source: Duke University