A seven-degree error. That is the margin of disorientation Manx shearwaters experience when their internal biological clocks clash with the sun’s position during long-distance flights across the Atlantic Ocean, according to research published in the journal Science.
The phenomenon mirrors human jet lag. As these seabirds travel rapidly across longitudes, their circadian rhythms fall out of sync with the physical world, causing them to veer off course.
On fast flights across the Atlantic, the body clocks of Manx shearwaters get out of sync with local time, leading them to veer away from the most direct flight path https://t.co/Sixi4fXvLc
The mechanics of ‘flap lag’
Manx shearwaters, close relatives of the albatross, operate on a breeding cycle. Partners mate for life and lay a single egg; while one parent incubates the egg nonstop, the other hunts for fish and squid hundreds of miles into the North Atlantic. These foraging trips are often completed in about a day.
Patrick Lewin, a behavioral ecologist at the University of Oxford, used GPS tracking data collected by colleagues over 20 years to identify what he calls “flap lag.” Because the birds rely on the sun as a compass, they must possess a precise understanding of the time of day to maintain a heading—distinguishing the east of the morning from the west of the evening.
“To use the sun as a compass you have to know what time of day it is,” Lewin said. “If the shearwaters had the wrong time of day, they would fly the wrong way.”
Three miles off course
The data shows that as birds rush back to their nests, they drift. The maximum deviation recorded was seven degrees, which pushed a bird roughly three miles off track during a 600-mile flight.
While a three-mile deviation over such a distance may seem negligible, the discovery offers a rare window into the active decision-making of wild animals. Documenting these real-time navigational choices has historically been difficult for species ranging from chipmunks to corals.
New Scientist reports that on fast flights across the Atlantic, the body clocks of Manx shearwaters get out of sync with local time, leading them to veer away from the most direct path.https://t.co/bz8VExJp4O
Tracking biological navigation
The use of GPS trackers in remote environments is what made the discovery possible. Alice Boyle, a biologist at the Centre for Animals on the Move at Western University in Ontario, Canada, noted that this technology allows researchers to see exactly how birds manage vast distances.
The result is a concrete example of biological navigation in action. Where humans experience jet lag, the Manx shearwater experiences it as a physical, navigational drift.
The study highlights the constant tension between a bird's internal rhythm and the rapid change in longitude during a 600-mile journey.
