Can Penguins Fly?

Watch an emperor penguin enter the water and the question answers itself in about three seconds. The wings fold back, the body goes horizontal, and the bird accelerates through a burst of white bubbles. It is not swimming the way a duck swims. It is flying - through a medium 800 times denser than air, using the same basic stroke that kept its ancestors airborne, repurposed at enormous evolutionary cost.

No, penguins cannot fly. But the interesting question is not whether they can. It is what they gave up, what they gained, and why the trade locked in so completely that no penguin has glided since at least 60 million years ago.

A wing that could not serve two masters

A 2013 study by Kyle Elliott (University of Manitoba) and colleagues, published in the Proceedings of the National Academy of Sciences, measured energy costs across multiple seabird species, including thick-billed murres (Uria lomvia) - diving birds that still fly. The murre expended 31 times its resting metabolic rate during flight, the highest figure ever recorded for any living bird. The finding confirmed what anatomy suggested: a wing optimised for underwater propulsion becomes progressively more expensive to fly with, until the bird that keeps trying is outcompeted by the one that has stopped.

The penguin’s flipper is not a failed wing. It is a wing that finished its conversion.

The oldest known penguin fossil, Waimanu, was recovered near New Zealand’s Waipara River and dates to roughly 60 million years ago. Its bones were already flattened and denser than those of flying birds, though not yet as compressed as a modern penguin’s. No flying penguin fossil exists in the record. By the time penguins appear at all, the trade was done.

What the bones became

In a flying bird, the wing bones are hollow, lightened by air sacs that reduce weight for takeoff. Penguin bones are solid. They are also shorter, harder, and fused at the joints in ways that make the flipper rigid along most of its length - a stiff hydrofoil rather than an articulated lever. The humerus, radius, and ulna are flattened and broadened to maximise surface area for pushing through water. The elbow and wrist joints have fused so tightly over evolutionary time that a penguin cannot fold its flipper the way a sparrow folds a wing.

A 2024 study published in the Journal of the Royal Society of New Zealand, led by Dr. Tatsuro Ando of Japan’s Ashoro Museum of Paleontology, described a newly analysed fossil penguin, Pakudyptes hakataramea, recovered in South Canterbury, New Zealand, in 1987. The specimen showed intermediate wing geometry - angled, with restricted elbow movement - and filled in a portion of the transition from Waimanu’s partially modified flipper to the rigid paddle of modern species. The fossil record now suggests the wing evolution accelerated through the Late Oligocene and Early Miocene, roughly 23 to 33 million years ago.

The muscular architecture changed in parallel. The penguin’s pectoral girdle - the shoulder complex of scapula, coracoid, and clavicle - grew proportionally larger and more solid, anchoring pectoral muscles powerful enough to drive a streamlined body through cold water. Emperor penguins (Aptenodytes forsteri) dive on single breaths to depths exceeding 500 metres. A peer-reviewed activity budget study published in PLOS ONE recorded maximum individual dive depths of 514 metres, the deepest confirmed for any bird.

The Gentoo and the murre

The Great Auk - a member of the alcid family, larger and heavier than surviving auks - crossed the same threshold independently in the northern hemisphere and lost flight entirely before being hunted to extinction in the 19th century. Two lineages, one southern and one northern, arrived at the same solution. The difference is that penguins survived, though sailors and explorers did test whether you can eat them.

Gentoo penguins (Pygoscelis papua) are the fastest recorded penguin swimmers, reaching 36 km/h in short bursts, according to Audubon. Emperor penguins are the largest living species - close to four feet tall and weighing more than 77 pounds, per Audubon’s records - and they hold their breath for up to 22 minutes. That breath-hold is not a curiosity. It is why the trade happened. Every one of those deep dives is a hunt, which is the whole point of what penguins eat and how they chase it.

The flipper achieves underwater speed the same way a wing achieves lift in air: by generating pressure differences across its two surfaces. On each downstroke and upstroke the flipper acts as a hydrofoil, producing thrust and lift simultaneously. Unlike most swimming birds, which pull primarily on the downstroke, penguins extract power from both halves of the stroke - the same double-stroke pattern a swift uses in air.

An evolutionary cliff with no way back

John Speakman, chair of zoology at the University of Aberdeen and a co-author on the 2013 PNAS study, put the constraint plainly: wings cannot be optimised for two media at once. Once a lineage crosses far enough toward aquatic propulsion, flight becomes prohibitively expensive and the bones, joints, and muscles that would allow it begin to fuse and shrink. There is no gradual return. The fossil record has no penguin that re-evolved flight. The pathway closes.

This is what makes penguins unusual among flightless birds. Ostriches and emus lost flight because they grew too large for takeoff on land. Penguins lost it because they became too good at something else - because the water was worth more than the sky.

Of the 18 recognised penguin species, nine are now threatened or endangered according to IUCN assessments. The African penguin (Spheniscus demersus) was uplisted to Critically Endangered in 2024 after its population fell to roughly 9,900 breeding pairs - a 93 percent decline over 70 years, per IUCN data. Emperor penguins, whose breeding depends on stable Antarctic sea ice, are the subject of a 2025 proposal to uplist them from Vulnerable to Endangered as the ice they need retreats.

The bird that gave up the sky 60 million years ago to master the ocean now faces an ocean that is changing faster than evolution can answer.