This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A study led by Oxford University has found that seabirds flying long distances across the Atlantic can experience a mismatch between their internal body clocks and local time (the same process that leads to jet lag in humans), causing them to make predictable errors when navigating by the sun. The results have been published in the journal Science.
Many animals, 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.
However, when they travel rapidly east or west during the day, their internal clocks may temporarily become out of sync with local solar time. This could cause them to misjudge the sun's position and fly slightly off course. To investigate whether this happens in the wild, researchers led by Oxford University's Department of Biology analyzed 20 years of GPS tracking data from 1,045 Manx shearwaters, covering 3,688 foraging trips.
Manx shearwaters (Puffinus puffinus) breed on islands off the western coasts of the U.K. and Ireland. They regularly travel hundreds of kilometers out to sea in search of food, sometimes reaching feeding grounds around 1,000 km (621 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 we do when we fly into earlier time zones).
As a result, their internal clocks may lag behind local solar time by up to around one hour. The researchers found that the birds' flight directions showed systematic deviations consistent with the predicted effects of these 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 team used statistical models to compare the observed deviations with those predicted from the birds' movements and the changing position of the sun. The results supported the sun-compass explanation, which also fit the data better than an alternative explanation based on changes in the Earth's magnetic field. The researchers found that these navigational errors persisted even when the birds were flying along visible coastlines, where landmarks could help guide them.
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