The Newly Discovered Giant Flores Stork

ResearchBlogging.orgA new species of stork has been identified from Flores, which is the Indonesian island on which the famous “hobbit” fossils have been found. The “hobbit” is a form of hominid (human relative) that seems to be a diminutive form of Homo erectus but different enough from that widespread species to give it a distinct taxonomic status, Homo floresiensis. The Flores hominids were probably about 120 centimeters in height, and the new stork was probably about 180 centimeters in height. The following artist reconstruction is meant to demonstrate bigness of the stork in relation to our diminutive relative:

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More on that artist’s reconstruction later.

The stork appears to have existed during and prior to the Last Glacial maximum, with remains dating to about 20,000 to 50,000 years ago. It is a “Marabou” stork (sometimes spelled Maribou or Maribu, the “m” is variously capitalized) of the genus Leptoptilos and is called Leptoptilos robustus sp. nov.. Dimensions of the bones found of this stork are virtually the same as Leptoptilos dubius which is a once widespread but now very restricted Asian marabou.

My own experience with marabou storks is with the African variety, Leptoptilos crumeniferus. Both of these living storks max out at about 150 cm in height, and the African marabou is a village scavenger. Fishing villages in Central Africa tend to have a population of these storks, and there are times when a village street may have more of these giant birds standing around than there are humans. They are unafraid to fly very close to a human. The first time a 1.5 meter tall bird swoops to within three feet and stands there with it’s enormous beak set to one side as it eyes you, one appreciates the fact that they are not larger than they are. Recommendation: If you are in a fishing village in Central Africa and stop in a restaurant to eat some fish, don’t bother with the takeout bag. You’ll get mugged by the birds.

Anyway, one bone in the newly discovered extinct species, a leg bone, is much larger and heavier than in the living species. The increased size pushes the stork to a greater height, and the heaviness indicates that the mass of the animal was also greater, suggesting that Leptoptilos robustus would have had limited flight abilities.

The authors suggest that the unusual ecology of Flores accounts for a mainly ground dwelling bird. Essentially, there would have been no mammalian predators so flight was selected against, and an abundance of ground food and other factors that would cause this stork to do what the other vertebrate fauna seems to have done at Flores: Get strange, in terms of size or other aspects, as a result of living on the island.

Of course, I would have thought hominids would have been a predator, but it is probably the absence of felids on the island that matters more.

Now, back to the artists reconstruction above. When I saw this, something did not look right, then I noticed the breasts on the hominid. This photograph shows a larger-end extinct stork next to a shortish (female) hominid, in order to emphasize the differences. Then, I read that the bones were all the same size as modern marabou storks. Modern marabou storks are impressively large but if this extinct form was close to the same size, then I figured they would not be a lot bigger than flores hominids, and just as interestingly, they are not a lot bigger than existing storks. It is not as though a six foot tall species of canary has been found. Storks are huge, and this is just another stork that is a bit huger than the other ones, quite possibly related to the fact that lots of animals were bigger during the Pleistocene than they are now. In fact, relative to other animals (mainly mammals) that I can think of, the difference between living marabou storks and this extinct form is perhaps unimpressive.

So, I made a graphic showing in scale the height of the depicted hominid, the height of the average Flores “hobbit,” the height of a living male marabou, and the height of the extinct marabou. The heights for the reconstructed individuals are scaled to the depicted extinct bird which I assume is 180 cm.

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Having just thrown a wet blanket on this research, I want to quickly add that this is in fact an important find. Not only is it a new species, but it shows the distribution of this genus during the Last Glacial Maximum to have included Flores. Also, the fact that the bird is larger and less likely to have flown is very important and adds an important piece to the palaeoecological puzzle that is Flores. The fact that the artist rendering shows a bird that seems large enough, as one of my facebook friends commented, to have been the stork that delivered adult hobbits, does not detract from the importance of this find, but it does demonstrate, once again, that hype and exaggeration is out there and must always be guarded against. There were in fact hominids and storks of the relative size as depicted, and in fact if you showed a pre-adolescent female hobbit, the comparison would still be true and even more impressive. But there was on average less of a contrast than shown.

Given the storks and the hobbits, I wonder which one scavenged off the other more often?

MEIJER, H., & DUE, R. (2010). A new species of giant marabou stork (Aves: Ciconiiformes) from the Pleistocene of Liang Bua, Flores (Indonesia) Zoological Journal of the Linnean Society, 160 (4), 707-724 DOI: 10.1111/j.1096-3642.2010.00616.x

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Comments

  1. #1 Andy
    December 12, 2010

    Very cool

  2. #2 Phillip IV
    December 12, 2010

    I bet the artist worked from the 1.06 cm body height estimated for the type specimen of the species, LB1, who happened to be at the lower end of the range – might still have done it on purpose, though, to arrive at a more visually impressive height difference. But, regardless of the illustration, at least one of the headlines announcing the find read “Hobbit-eating giant stork discovered” – so, no way how careful a study is about avoiding sensationalist phrasing, journalists will still make up the difference. (And, admittedly, a headline like ‘fossils of slightly larger than usual stork discovered’ probably isn’t a great attention getter.)

  3. #3 ridelo
    December 12, 2010

    Another argument for The Stork Theory! Them storks had an easy life there on Flores. So big storks, so small baby’s.

  4. #4 Achrchno
    December 12, 2010

    >Essentially, there would have been no mammalian predators so flight was selected against,

    But there were Komodo dragons there, right? I’m unclear on whether loss of flight would have been all that desirable. Cost/benefit?

  5. #5 Greg Laden
    December 12, 2010

    And actually, feline mammalian predators would hunt the diurnal storks at night, when the would be at a disadvantage even if they flew.

  6. #6 Achrachno
    December 12, 2010

    >feline mammalian predators would hunt the diurnal storks at night

    How do the African storks get around this problem? Leopards and such are pretty common in Africa. Tree tops, I imagine.

    If the Flores stork was flightless, and if K. dragons were there at the same time, the storks obviously had some way of dealing with that lizard predator problem. Of course, the dragons are still there and the storks are gone. Perhaps they had an imperfect predator avoidance strategy.

    I wonder if the storks might even have been dragon predators. Dining on the young might keep adults down in numbers. Many ideas are possible when speculation is not constrained by a lot of pesky facts.

  7. #7 Greg Laden
    December 12, 2010

    How do the African storks get around this problem? Leopards and such are pretty common in Africa. Tree tops, I imagine.

    They’re big and scary, and don’t have much meat on them. A leopard can more easily kill an antelope and get lots of meat.

    K. dragons were there at the same time, the storks obviously had some way of dealing with that lizard predator problem.

    I’ve seen Komodo dragons, and I’ve seen (and eaten) the almost as large monitors of the rain forest in Africa, and I’ve seen the marabou storks. These storks are huge, strong, and have giant sharp beaks. I don’t think there’s much of a contest.

    Of course, the dragons are still there and the storks are gone.

    Good point. The modern Holocene Marabou of the region may have been wiped out by humans more recently, not sure.

    I wonder if the storks might even have been dragon predators.

    Quite possibly. Or at least, eggs and babies.

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