Manx Shearwaters Veer 15 Degrees Off Course as Jet Lag Skews 600-Mile Return Flights
Updated
Updated · The Guardian · Oct 29
Manx Shearwaters Veer 15 Degrees Off Course as Jet Lag Skews 600-Mile Return Flights
3 articles · Updated · The Guardian · Oct 29
Summary
20 years of GPS data showed Manx shearwaters returning to UK colonies after Atlantic foraging trips drift off course when rapid eastward flights leave their body clocks up to an hour behind local time.
The mismatch matters because the birds navigate with a sun compass: if internal time is wrong, the sun appears farther around the sky than expected and their heading shifts.
Adult birds usually corrected the error in flight, limiting the impact to about 15 degrees and roughly 3 extra miles on a 600-mile journey; the effect persisted even when they followed coastlines.
First-time foragers face the bigger risk, with the study estimating deviations of hundreds of miles because they lack the map sense adults use to recover their route.
The Science study strengthens evidence from lab work that biological clocks shape wild-animal navigation, though an outside expert said the real-world consequences for returning adults remain unclear.