Rapid longitudinal flights cause time shifts and Sun compass error

Many animals use the Sun compass to guide their movement, sometimes over thousands of kilometers. Consistent use of the Sun compass relies on the endogenous clock to track the Sun's arc, yet animals traveling east-west experience time shifts, potentially causing mismatches between their internal clock and local time. Using GPS, we reveal that Manx shearwaters (Puffinus puffinus) experience such shifts during homing flights, generating predictable errors in Sun compass orientation. Use of the Sun compass persists even when shearwaters have access to compass-independent cues during coast following. Our findings provide a new avenue for chronobiology research in the wild, suggesting that rapid longitudinal movements may affect other processes governed by the endogenous clock and that conserved chronobiological mechanisms impose substantial constraints on navigation.