A new study finds that Manx shearwaters fly so fast that their internal clocks get out of sync with local time. These jet lag-like time shifts confuse their sun-based compasses, causing them to become a bit disoriented and fly slightly off course
Sarah Kuta | Daily Correspondent
November 4, 2026 5:40 p.m.
Traveling rapidly across multiple time zones often throws our internal clocks out of whack. But new research suggests jet lag is not unique to humans—some birds may also experience it.
A new study published October 29 in the journal Science finds that the internal clocks of Manx shearwaters can get out of sync with local time because the birds fly so fast. These jet lag-like time shifts confuse their sun-based compasses, and cause them to become slightly disoriented and fly a little off course.
Black on top and white on bottom, Manx shearwaters are medium-sized seabirds that spend most of their lives flapping over the open ocean. But in late winter and early spring, roughly 80 percent of the world’s population returns to the steep, grassy islands off the western coasts of the United Kingdom to breed. Here, they reunite with their lifelong mates and nest in underground burrows, with females laying one egg that eventually hatches into a fluffy chick.
Adult birds head out in search of food, bringing back tasty morsels of herring, sardine and sprat to feed their growing chicks. The birds that nest near the U.K. regularly travel more than 600 miles west from their breeding islands to forage in the food-rich waters of the Irish Sea and the northeast Atlantic Ocean. Once they’ve filled their bellies, they make the return eastward journey, navigating back to their colonies with “remarkable efficiency,” the study’s co-authors write in the paper.
Quick fact: Eating habits
Shearwater chicks are so well-fed by their parents that they become too big to leave the nest. They often need to slim down a bit before fledging.
Scientists think Manx shearwaters successfully find their way back home by using the sun as a compass, determining which direction to fly based on its position in the sky. But “to use the sun as a compass, you have to know what time of day it is,” lead author Patrick Lewin, an ecologist at the University of Oxford, tells NPR’s Geoff Brumfiel, since the sun’s overhead position changes throughout the day as the Earth rotates on its axis. Manx shearwaters rely on their internal clocks to help make sense of the sun’s movements and stay on track.
Scientists wondered whether the birds’ speedy east-bound homing journeys might be messing with their internal clocks—similar to jet lag in humans. They theorized that, as the birds zip across the ocean, their internal clocks do not keep pace with the changes to local time, which could affect their sun compasses and, in turn, their overall navigational accuracy.
To test this idea, researchers analyzed 20 years’ worth of GPS tracking data from 1,045 wild breeding Manx shearwaters. The birds made 3,688 trips between their breeding grounds and foraging grounds, but the scientists were most interested in their homing flights, so they isolated 1,837 of their eastward, home-bound journeys.
The researchers predicted that, as the birds headed east, jet lag would cause them to fly slightly off course in a clockwise direction. Those predictions were borne out by the data, which revealed that the birds veered clockwise by as much as 15 degrees.
To be sure jet lag was responsible for these small orientation errors, the team considered other possible factors, such as the strength of crosswinds and distance from the colony. But “the one thing that best predicted the observed changes in shearwaters’ orientation was always this sun compass effect,” Lewin tells NewScientist’s Michael Le Page.
The birds continued to fly slightly off course even when they were flying alongside coastlines, a surprising finding that suggests Manx shearwaters rely on multiple cues for navigation—and continue using multiple methods even when they give conflicting directions.
That makes sense to Sangeeta Rani, a chronobiologist at the University of Lucknow who was not involved with the research. “After all, if I have marked a path for myself in the woods, my innate ability is not to mindlessly follow the markings,” Rani tells Anirban Mukhopadhyay for ScienceNews. “It is to find out what’s missing and still find my way back.”
Rani adds that the birds’ reliance on multiple navigational methods could serve them well in the future, when climate change and human development could make the landscapes they’re familiar with unrecognizable.
Since Manx shearwaters are covering such long distances, these subtle detours probably don’t make that much of a difference to their overall journeys: The researchers calculated that, for a bird traveling roughly 620 miles, a seven-degree compass error would only add roughly three extra miles to the trip. This is probably why Manx shearwaters haven’t evolved some way of avoiding jet lag, the researchers posit.
The study focused only on Manx shearwaters, but the researchers suspect other creatures that travel long distances—more species of birds, as well as some bats and insects—might also experience jet lag. It probably doesn’t affect birds when they migrate, however, because most migrations follow north-south routes, Ken Cheng, an emeritus comparative cognition scholar at Macquarie University who was not involved with the study, tells NewScientist.
Now that scientists know Manx shearwaters experience jet lag, the next step is to understand whether and how it affects them.
“Do they mistime critical behaviors? Do they experience physiological side effects like we do?” Lewin says in a statement. “Perhaps these birds that routinely travel long distances could help teach us how to cope with and treat jet lag to avoid the really negative effects it can have on our health.”
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Source: Smithsonian Magazine · Sarah Kuta
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