Study
High flight costs, but low dive costs, in auks support the biomechanical hypothesis for flightlessness in penguins
Elliott, Kyle H.; Ricklefs, Robert E.; Gaston, Anthony J.; Hatch, Scott A.; Speakman, John R.; Davoren, Gail K.
Proceedings of the National Academy of Sciences, 2013
Energy expenditure in flight and in diving was measured in thick-billed murres and tufted puffins — wing-propelled divers that still fly — using doubly labelled water together with activity loggers, allowing the cost of each activity to be separated in free-living wild birds.
- Studied in
- Uria lomvia, Fratercula cirrhata
- Sample size
- 41 wild birds measured with doubly labelled water
Flight in these birds is exceptionally expensive, the highest mass-specific flight cost recorded for a vertebrate, while their diving costs are low. The two demands pull wing design in opposite directions: a wing efficient underwater is a poor wing in air.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
The results support the biomechanical hypothesis that flightlessness in penguins evolved because a wing cannot be optimised simultaneously for flight and for underwater propulsion, so lineages committing to diving pay steeply rising flight costs.
How NatureHQ reads it
This is the study to reach for when someone says penguins cannot fly because they are too heavy. Weight is a consequence, not the cause. What the measurements show is a genuine trade-off in wing shape, caught in the act in birds that still do both and pay dearly for it. Penguins are not failed fliers; they are the endpoint of a lineage that kept choosing the water. The comparison is indirect by necessity — no penguin flies, so the transition has to be studied in the birds still making it — and that is the study's main limitation as well as its cleverness.
- The transition is inferred from auks, not observed in penguins.
- Doubly labelled water gives average expenditure over a period, not instantaneous cost.
- Other hypotheses for flightlessness, including predator release on breeding islands, are not excluded.
Costing the wing that has to do both jobs
Did penguins lose flight because a wing cannot be good in air and underwater at the same time?
What this study is used for on NatureHQ
One study can inform several subjects. Here is everywhere this one is cited.
Published by: Proceedings of the National Academy of SciencesPublished in PNAS.
doi.org/10.1073/pnas.1304838110
This reference was resolved automatically against Crossref on 2026-08-11.
NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-08-11.