In recent years, gray whales have gotten stranded on beaches more frequently—possibly driven by a combination of disease, starvation, naval sonar and seismic air guns used for oil exploration. Now, researchers may have identified another unexpected factor that leads gray whales to shore: solar storms.

Solar storms, also called geomagnetic storms, happen when the sun lets loose a burst of intense radiation and charged particles. These events manipulate the Earth's magnetosphere, which usually deflects most of what the sun emits. Intense storms can even mess with Earth's magnetic field, causing disruptions to radio communications and GPS satellites. Likewise, animals—like songbirds, sea turtles and spiny lobsters—that rely on the magnetic field to navigate is affected by these solar tantrums.

Gray whales migrate mostly by sight, but some scientists suspect they could also navigate by magnetism—though evidence to support this theory is inconclusive, reports Douglas Main for National Geographic. In a study published this week in the journal Current Biology, researchers may have found a link between gray whale strandings and solar storms, which may warrant further investigation into gray whales’ abilities to sense Earth’s magnetic field.

But doing so is easier said than done. To tell whether an animal can sense magnetic fields, researchers usually put that animal in a controlled environment, like a box or enclosure. Then, they change the direction of the magnetic field that the creature is sitting, standing or swimming in. For a European robin, which is a plump five-and-a-half inches long, that’s fairly straightforward. But with gray whales, which are larger than school buses and weigh up to 40 tons, it's not so simple.

“[Gray whales] have some of the most insane migrations of any animals on the planet,” Duke University biophysicist Jesse Granger tells the Atlantic. “Some of them almost go from the equator to the poles, and with astounding precision, traveling to the exact same area year after year.”

Solar storms, however, interfere with magnetic fields naturally. So Granger wondered if, by comparing frequencies of solar spots—dark points on the sun’s surface that indicate a flare up—to whale strandings that seem to be caused by mistaken directions, her team might find evidence of magnetic sensitivity in whales. To analyze that data, the team needed an expert in solar storms.

“This was like a dream request,” Lucianne Walkowicz, an astronomer at the Adler Planetarium in Chicago, tells the New York Times’ Joshua Sokol. Walkowicz wanted to be a marine biologist before she became an astronomer. “And I finally got to do something in marine biology, even though I didn’t study it.”

The whale data came from 31 years’ worth of data on gray whale strandings, pared down to the 186 events when the whales seemed to have been beached alive and unharmed, rather than because of injury, illness or starvation. The team found that strandings were twice as likely on days with high sun spot counts, and four times as likely on days when the sun is putting out especially strong radio waves, compared to days without.

The correlation was very strong, but still doesn’t necessarily prove that solar storms caused the strandings. Biologist Josh Calambokidis, who helped gather the data that the researchers used for their analysis, expressed concerns to the New York Times that the cases of “lost” whales probably also included beachings from more dire circumstances, like a mass stranding in 1999 and 2000 that was caused by starvation but also coincided with solar activity.

Others found the study more persuasive. “The study convinced me there is a relationship between solar activity and whale strandings,” University of North Carolina biologist Kenneth Lohmann, who did not participate in the research, tells the Times. To Ed Yong at the Atlantic, Lohmann explains further: “This study has been done in a particularly rigorous way… It is conceivable that the effect on the whales involves something that does not directly tie into navigation.”

Granger and her team suggest that the radio-frequency radiation interferes with chemical reactions in the whales’ eyes that normally allow the creatures to sense the magnetic field. With the reactions scrambled by the solar storm radiation, the whales could temporarily lose that sense.

But definitive proof of whales’ magnetic sixth sense remains tricky to find. As Granger’s colleague Sönke Johnsen wrote, per the Atlantic, finding the sensor is like finding a “needle in a needle stack.”