Seabird Jet Lag Is Real, New Science Study Shows

Seabird jet lag is real, and a new study in Science just proved it: Manx shearwaters that race east across the Atlantic arrive with body clocks out of sync, and they drift off course because of it.

What the researchers found

A team led by Oxford University's Department of Biology analysed twenty years of GPS tracking data from one thousand and forty-five Manx shearwaters, covering three thousand six hundred and eighty-eight foraging trips, according to EurekAlert. The birds breed on islands off the western coasts of the UK and Ireland, and they regularly travel hundreds of kilometres out over the ocean to feed.

The finding is simple and a little wild. When the birds speed back east toward their nests, their internal clocks lag behind local solar time, much like a human stepping off a long flight from London to Tokyo.

How a bird gets jet lag

Shearwaters rely on a sun compass. If you know the time, you can hold a heading by keeping the sun at a set angle. But the compass only works if the clock is right.

New Scientist explained it with an example: at noon a bird heading east needs the sun at a right angle, due south. If it flies fifteen degrees of longitude east, local time is already one in the afternoon while its body still says noon, so the sun is not where it expects it. The bird misjudges its heading, according to New Scientist.

In the study, sunrise happened an hour earlier at the destination, so the bird's perceived time lagged local time by an hour and the sun sat roughly twenty degrees further clockwise than expected.

Off course, but not lost

Do not picture birds wandering lost over the sea. The errors were small. The birds veered by as much as fifteen degrees, and the Guardian reported that after correcting their course, this added only about three miles to a six hundred mile journey, according to The Guardian.

The adults can fix their bearings in flight because they also carry a mental map. Lead researcher Dr Patrick Lewin told The Naked Scientists that the result is a shallow spiral toward the colony rather than a straight line, which is detectable only with huge amounts of tracking data.

Why scientists trust the result

This was not a controlled experiment, so cause and effect needs care. Ars Technica reported that across three hundred and thirty-five homing flights made out of sight of land, the birds veered just as the sun compass predictions said they would.

The team also checked other explanations. They calculated the biases that crosswinds, the Coriolis effect or a magnetic compass might introduce, and none fit the data well. Lewin said the observed biases match the sun compass predictions by far the best.

Why this matters beyond birds

Plenty of animals use the sun to steer, including insects, fish, turtles and other birds. Experiments have shown that if their internal clocks are reset with artificial light and darkness, they head in the wrong direction. What makes this work stand out is that it shows the same effect in the wild, on a bird making real journeys, with no lab tricks involved.

Most long-distance travellers in nature move north and south, which keeps their clocks aligned with the sun. Shearwaters are unusual because they commute east and west, and that is exactly why seabird jet lag shows up so clearly in their tracks. The paper itself was published in Science and was summed up by editor Sacha Vignieri as proof that these birds make predictable errors tied to a clock and sun compass mismatch, according to Science.

What comes next for seabird jet lag

The big open question is whether the mismatch hurts the birds. Lewin said the next step is to learn whether they mistime critical behaviours, whether they feel physiological side effects as people do, and whether the mismatch is as damaging to their health as jet lag is to ours.

There is a fun upside. Birds that routinely cover long east-west distances could one day help researchers understand how to cope with and treat jet lag, which in humans brings disturbed sleep and fatigue.

So the next time you land after a red-eye and feel completely scrambled, remember that a tiny seabird is dealing with the same clock problem, and still gets home. For more on the natural world, check out science coverage and climate news on the site.