Body-clock lag disrupts seabirds’ navigation on flights home

Manx shearwaters returning to colonies on the UK’s west coast can lose their bearings when rapid eastward flights leave their internal clocks behind local time, according to Oxford researchers. Their analysis of 20 years of GPS tracking data, reported in Science, linked clock mismatches of up to about an hour with errors in the birds’ sun-based navigation.

Adult birds corrected their headings after straying by as much as about 15 degrees, adding an estimated three miles to a 600-mile journey. Researchers said inexperienced birds could face much larger deviations because they lack the navigational knowledge to reorient themselves. An independent expert cautioned that the study did not establish the consequences of the observed errors.

Much research on birds’ biological clocks takes place in laboratories, making these observations of wild shearwaters significant. Navigation errors persisted even along coastlines where landmarks were available. That supports the researchers’ interpretation that the sun remains an important directional reference, although the tracked adults still returned to their colonies.