Seabirds returning from long-distance foraging trips can be thrown hundreds of miles off course by a phenomenon akin to jet lag, according to new research. A study led by Dr. Patrick Lewin, a behavioural and sensory ecologist at the University of Oxford, found that when Manx shearwaters fly rapidly eastward across the Atlantic to return to their colonies on the UK's west coast, their internal body clocks fall out of sync with local time.
The analysis of 20 years of GPS tracking data showed that as these birds crossed lines of longitude, their internal clocks lagged behind local time by up to an hour. Because shearwaters rely on the sun as a compass, they must adjust their heading based on the time of day tracked by their biological rhythms. When this internal clock is misaligned with the actual position of the sun, the birds miscalculate their direction, causing them to drift off course.
The impact of this navigational error varies significantly depending on the bird's experience. Adult shearwaters are generally able to correct their bearings while in flight, limiting their deviation to approximately 15 degrees. This correction adds only about three miles to a typical 600-mile journey. However, first-time foragers lack the map sense required to reorient themselves effectively when they lose their way. Consequently, these inexperienced birds risk flying hundreds of miles off course due to these sun compass errors.
The study, published in Science, noted that these errors persisted even when birds followed coastlines where landmarks were available, reinforcing the conclusion that the sun plays a central role in anchoring their sense of direction. While sunset and sunrise normally help keep the birds' clocks synchronized with local time, the rapid eastward travel disrupts this process.
Professor Richard Holland of Bangor University, who was not involved in the study, described the findings as significant for confirming that wild animals rely on sun compasses even when they are inaccurate. Although the consequences of these errors remain unclear since the birds eventually return to their colonies, the research highlights the critical importance of biological rhythms in animal behavior and navigation.
Sources: The Guardian Science.