Can birds get jet lag? New study reveals answer

By Stephen Beech

Seabirds can suffer “jet lag” during long-distance flights — causing them to lose their way, reveals new research.

Oxford University scientists found that gulls flying hundreds of miles across the Atlantic may experience a “mismatch” between their internal body clocks and local time.

The same process which leads to jet lag in humans can cause the seabirds to make predictable errors when navigating by the sun, shows the study published in the journal Science.

The research team says their findings may help humans cope with the sometimes debilitating effects of long-haul flights.

It has been previously shown that many species, including birds, use the sun to find their way.

But because the sun moves across the sky throughout the day, they need an accurate internal clock to interpret its position correctly.

Normally, birds reset their internal clocks using sunrise as a cue.

But when they travel rapidly east or west during the day, their internal clocks may temporarily become out of sync with local solar time.

Scientists say that could cause them to misjudge the sun’s position and fly slightly off course.

To investigate whether that happens in the wild, the research team analyzed 20 years of GPS tracking data from 1,045 Manx shearwaters, covering 3,688 foraging trips.

The species breed on islands off the western coasts of the U.K. and Ireland and regularly travel hundreds of miles out to sea in search of food, sometimes reaching feeding grounds around 600 miles west of their breeding colonies.

When returning to their nests, the birds can travel rapidly eastward across lines of longitude, moving into places where the sun rose earlier — just as people do when taking long-haul flights into earlier time zones.

As a result, the birds’ internal clocks may lag behind local solar time by up to around one hour.

The research team found that the birds’ flight directions showed “systematic deviations” consistent with the predicted effects of the time shifts on their sun compass.

As the birds traveled eastward, they tended to deviate clockwise from their expected direction, as would be predicted if their internal clocks were running behind local time.

The researchers used statistical models to compare the observed deviations with those predicted from the birds’ movements and the changing position of the sun.

Their findings supported the sun-compass explanation, which also fit the data better than an alternative explanation based on changes in the Earth’s magnetic field.

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The researchers found that the navigational errors persisted even when the birds were flying along visible coastlines, where landmarks could help guide them.

When the predicted compass error pointed toward land, the shearwaters tended to fly closer to the coast.

When it pointed away from land, they tended to fly farther out to sea.

The researchers say that suggests that the birds continued to rely on their sun compass even when other navigational cues were available, rather than simply following the coastline.

Study leader Patrick Lewin said: “It’s amazing to think that billions of migratory animals look up to the sun for direction, relying on clocks silently ticking away inside them, and that errors in those clocks can cause them to take tiny shifts off course.”

Co-author Tim Guilford added: “It’s inherently difficult to study the cognitive processes of animals in the wild, so it’s exciting to realize that if we measure their natural movements carefully enough we can reveal the underlying behavioral mechanisms.”

He said the navigational errors were relatively small, reaching around 15 degrees in the shearwaters studied.

Because the seabirds appear able to reassess their position and adjust their route home continuously, the additional distance traveled is likely to be modest.

For example, the researchers calculated that a shearwater returning from 1,000 kilometers (621 miles) away, with an average compass error of seven degrees and continuously correcting its course, would travel only around 5 kilometers (3.1 miles) farther to reach within 5 kilometers of its colony.

However, the team says their findings could have wider implications for animals that travel long distances without being able to correct their position continuously.

For example, in birds undertaking their first migration, small compass errors could potentially accumulate, shifting their eventual destination by hundreds of miles.

Because internal clocks regulate many aspects of animal behavior and physiology, the researchers suggest that similar time shifts could potentially have effects beyond navigation.

In humans, traveling rapidly across time zones can cause jet lag, which involves a mismatch between the body’s internal clock and local time and can lead to disturbed sleep, fatigue and other symptoms.

The tram say further research is needed to establish whether similar effects can occur in wild migrating birds and whether it could have consequences for their health, behavior and survival.

Lewin said: “Our results show that animals experience the same internal clock mismatch as we do during jet lag.

“The next step is to understand how that affects them. Do they mistime critical behaviors? Do they experience physiological side effects like we do?

“And is this mismatch as damaging to their health as jet lag is to ours?”

He added: “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.”