Turns out humans aren't the only travelers who get thrown off by crossing time zones too fast.
Wild seabirds called Manx shearwaters experience a bird version of jet lag during long ocean flights, according to a study published October 29, 2026, in the journal Science. Researchers led by Patrick Lewin at the University of Oxford found that rapid east-west travel can scramble the birds' internal clocks, causing them to misjudge direction while navigating by the sun.
Seabird jet lag shows up in two decades of flight data
Lewin's team didn't just watch a few birds fly around. They dug through GPS tracking records covering more than 20 years, pulling data from 1,045 wild Manx shearwaters and 3,688 foraging trips. These birds travel from breeding colonies in the United Kingdom out to feeding grounds in the Atlantic Ocean, sometimes flying as far as 1,000 kilometers away from home.
That's a huge amount of flight data to work with, and it let the researchers spot a pattern that would be nearly impossible to catch in a smaller study. The birds fly fast enough, and far enough east or west, that their body clocks start falling out of sync with the actual position of the sun in the sky where they end up.
Manx shearwaters use a sun compass to find their way, especially out over open water where there are no coastlines or landmarks to guide them. But a sun compass only works if the bird also knows what time it is. The sun sits in a different spot in the sky depending on the hour, so a bird with a confused internal clock can end up reading the sun's position wrong and heading the wrong way.
How the sun compass gets confused mid-flight
Lewin described the method behind spotting these errors in simple terms. "That means we can measure whether they're going a little bit too far clockwise or a little too far anticlockwise and compare that to what we would expect if they're using the sun as a compass and experiencing this time shift," he said.
When a shearwater flies quickly across lines of longitude, it can arrive somewhere that the sun says is a different time than what its body still thinks it is. That's the same basic mismatch that makes a human feel groggy and disoriented after flying across several time zones. The study summary noted that the birds' "flight directions showed 'systematic deviations' consistent with the predicted effects of the time shifts on their sun compass."
Coverage of the findings described the birds experiencing "time shifts, potentially causing mismatches between their internal clock and local time." The deviations weren't massive, but they were measurable and predictable. Science News reported directional errors as high as 15 degrees, while other reporting pointed to a maximum observed deviation closer to 7 degrees, which would nudge a bird about 3 miles off course over a 600-mile trip.
Why this matters beyond one small seabird
This isn't the first hint that birds might struggle with sun-based navigation after fast travel. Back in 2001, Science reported on shorebirds like plovers and sandpipers whose migration routes curved more and more southward as they flew east, a pattern researchers linked to the birds' internal clocks drifting out of step with local time.
What makes the new shearwater study different is the sheer scale and real-world setting. Instead of inferring clock confusion from a handful of birds, Lewin's team had decades of GPS tracks from over a thousand wild birds making thousands of actual foraging trips across the Atlantic. The directional errors they found closely matched what you'd expect if a sun compass were being thrown off by a lagging or racing internal clock, even though shearwaters likely have backup tools like magnetic or smell-based cues available to them.
EurekAlert's summary of the research pointed out that the deviations showed up even when other navigational cues were available to the birds, which strengthens the case that the sun compass itself was the thing getting tripped up. That's an important detail, because it means jet lag isn't just a human inconvenience tied to airplanes and schedules. It's a biological hiccup that can hit any creature whose navigation depends on matching an internal clock to the outside world.
What the birds actually experience and what comes next
To be clear, the shearwaters aren't collapsing with exhaustion or missing their nests entirely. The errors found in the study were modest, bending flight paths by single-digit to low double-digit degrees rather than sending birds wildly off track. The tracked shearwaters still completed their long foraging journeys and made it back to their breeding colonies, partners, and eggs.
What the research adds is proof that these small, predictable navigation slips are baked into how far and how fast these birds fly. No follow-up experiments, hearings, or new tracking projects have been announced yet based on the available reporting. But the study opens an obvious set of questions for scientists working on animal navigation: how fast do shearwaters reset their internal clocks, do other migratory species show the same pattern, and how much do backup senses like smell or magnetic fields help birds correct course once the sun compass goes wrong.
For now, the headline finding stands on its own. A bird that crosses the ocean fast enough can wind up just a little lost, not because it forgot the way home, but because its own internal clock briefly stopped matching the sky above it.
