Shearwaters can lose their solar bearings when their clocks shift
· BehindLines newsroom
Manx shearwaters returning to their colony appear to use a sun compass that long journeys can temporarily disrupt. A study presented by the University of Oxford on 29 October links deviations in their routes to a mismatch between the birds’ internal clocks and local solar time.
A predictable error in their journeys
The university release, distributed by Brightsurf, describes twenty years of GPS tracking, covering 1,045 birds and 3,688 foraging trips. During fast eastward returns, their heading shifts in the direction expected if the biological clock is running behind the sun’s local position.
Visible coastlines do not remove the effect entirely. Depending on the direction of the predicted error, the birds then travel closer to shore or farther offshore. The researchers favour this solar explanation over a change in the magnetic field.
These are clues drawn from movements, rather than a direct reading of a clock inside the brain. Possible effects on health or survival remain to be investigated.
Earlier research and deposited code
The research builds on work described in Patrick Lewin’s thesis, dated 2025 in Oxford’s catalogue. Its abstract already distinguished between solar cues used at sea and information from land, and described an experiment that artificially shifted the birds’ clocks. That background does not amount to an independent replication of the new study.
A Zenodo deposit bearing the scientific paper’s title provides the GPS processing and analysis script in the R language. Its first version is dated 19 October 2026. Making this code available helps others examine the method; it does not mean that another team has reproduced the analysis.
The October presentation therefore sheds light on a navigation mechanism. It neither demonstrates that all migrating birds experience the same effects nor measures human symptoms of jet lag in those birds.