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From flapper to flipper: how the penguin lost its flight

Penguins can move underwater with the speed of a swallow or swift, but cannot fly even as far as a chicken. How did a bird…

The emperor penguin: walking isn’t exactly its speciality, but you should see it swim. Uli Junz

Penguins can move underwater with the speed of a swallow or swift, but cannot fly even as far as a chicken. How did a bird that in some cases shuffles 40 miles to its breeding grounds on unsuitable flippers end up losing its ability to fly there quickly?

A team of researchers from the UK, US, Canada and China have put forward a theory of how the penguin lost its ability to fly, published in the Proceedings of the National Academy of Sciences today.

Professor John Speakman, Chair of Zoology at the University of Aberdeen, was part of the international team and carried out the number-crunching that showed how, over time, penguins found it more advantageous to have a wing suited to swimming than flying.

He said: “Wings that have to do two jobs, flying and diving, can’t be good at both. As a wing evolves to be better at diving it gets worse at flying, until the energy demands of flight become so great that eventually the penguin gives up flying altogether.”

The albatross is an example of a long, light wing well-adapted for flying, while a short wing with heavy bones like a penguin’s is more suited to swimming. “They are complete opposites,” Prof Speakman said.

As its wing evolved, the penguin would have become a better diver and a worse flyer, until one day the prospect of launching itself into the air with difficulty no longer appealed.

Dive-fishing auks are black and white like penguins, but airborne too. Kyle Elliott

To test the theory the team studied auks, a family of seabirds very similar to penguins, that catch fish below the water’s surface but which still have the ability to fly. Using the doubly-labelled water method, Speakman was able to work out how much CO2 the birds produced as they swam, flew, or sat about. From this he could extrapolate how much energy these activities needed.

He explained: “We found auks have exceptional diving abilities, almost as good as a penguin, but their flight costs are enormous – the highest ever measured. This matched the theory exactly.”

In their capacity to fly and dive they were “on the cusp” of becoming like penguins, he said. In fact the Great Auk, a species of auk hunted to extinction in the 19th century, had already lost the ability to fly, in keeping with the theory.

Had there ever been a flying penguin? “The fossil record doesn’t actually contain a flying penguin,” he said. “The first one we have was already flightless, and that was about 60 million years ago.”

So while it seems extremely maladaptive to see emperor penguins penguins wobbling miles across the ice to their rookeries, it stems from a trade-off far back in the evolutionary chain that saw their wings adapt to their increasingly aquatic environment and lose the ability to fly.

“When you see them swimming underwater,” Speakman said, “you truly get a sense of what they gained in return.”

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8 Comments sorted by

  1. Keith Thomas

    Retired

    Thanks for this. There's a nice video of little auks flying here:

    http://www.youtube.com/watch?v=RvGkVdLoJh4

    Despite their stumpy configuration, they don't appear to be reluctant flyers and the video shows them flying together in coordinated flocks. Not as synchronized as starlings, but nor do they display any reluctance to lift off and remain in the air. Looks as if they are not about to lose their flying ability.

    Incidentally, your opening para must be an exaggeration: surely penguins can't swim as fast as swifts can fly.

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    1. James Hill

      Industrial Designer

      In reply to Keith Thomas

      Though, of course, if they were Great Auks then they might, like penguins, or foie gras, be too heavy to fly.
      Their offspring would, however, appreciate those larger volumes of food, hauled shuffingly across the ice to their nesting spots, in their parents' "great" guts.
      I have had the privilege, while skindiving, of observing the speed of Fairy penguins , and they do "dart" about a bit.

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  2. Gavin Hinks

    Journalist at Freelance

    I'm not sure I get this. Without a fossil record it seems equally valid to propose penguins never flew, and therefore something else happened. Secondly, if Auks are on the cusp of becoming penguins, why don't they stop flying and become full-time swimmers? The implication is that swimming only is the rational evolutionary step.

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    1. Michael Parker

      Environment and Energy Editor at The Conversation

      In reply to Gavin Hinks

      Well I'm no palaeontologist, but the penguin is a flightless bird, and birds don't swim, they fly. So in the very distant past the penguin's ancestor was a bird that flew, before adapting to become one that didn't. In the same way the ostrich gave up flying in exchange for running, presumably.

      Auk's are 'on the cusp' in evolutionary terms, on evolutionary timescales. Penguins have no real predators on land and can walk to their rookeries, in however ungainly a fashion. But auks fly to their nesting grounds and so have retained the need to fly, however energy-intensive it has become as their wings become more adapted for swimming. What if their food source moved deeper, or swam faster, requiring better diving skills? If they could find somewhere else to nest and breed, perhaps that would be enough to push them over the evolutionary edge.

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    2. James Hill

      Industrial Designer

      In reply to Michael Parker

      What about the flightless cormorant of the Galapagos that Darwin described in "The Voyage of The Beagle".
      When it comes the evolutionary "niches", it seems to parallel Christ's statement "My father's house has a thousand mansions", what came first; the habitat or the inhabitant?
      Though there does not appear to be much that is heavenly about "McMansions", and the evolutionary prospects of those "adapted", however temporarilly, to live in them.

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    3. James Hill

      Industrial Designer

      In reply to James Hill

      A pardon, please, for casting the pall of politics, and religion, over the rare and pure pleasures of the naturalists' world.

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    4. Caleb Gardner

      Principle Research Fellow, Institute for Marine and Antarctic Studies at University of Tasmania

      In reply to James Hill

      The absence of a fossil record opens up that other old problem of whether penguins are birds that have evolved into fish or fish that have evolved into birds? Thanks James for bringing religion into this. It helps with auks of course because we have the guidance from the Vatican that puffins on the island of Skellig are indeed feathery fish and thus OK tucker for lent.

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    5. James Hill

      Industrial Designer

      In reply to Caleb Gardner

      Yes, the controversial fossil record and its interpretation.
      A biologist acquaintance used to like repeating "The ontology recapitulates the phylogeny",
      Something to do with fossils, thought you might be interested.

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