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Re: 11th specimen of Archaeopteryx



Thank Jason.  That's extremely interesting.


Well it just goes to show you can't always trust the literature.  This
is what Clive Roots (2006) ("Flightless Birds", Greenwood Publishing)
had to say about the kagu (p70):


     "...its [the kagu's] breast muscles have deteriorated to the
extent that its relatively large,
      broad, and rounded wings are useless for flight.  It lives in
forest and scrub, and when
      threatened it moves fast on its chicken-like legs, running down
mountain slopes and
      launching into a long and low graceful glide away from danger.
It is certainly the best
      glider of all the flightless birds."


And again, in the figure caption:


      "Completely flightless due to the deterioration of its breast
muscles, it still has large, broad,
       and rounded wings on which it glides for long distances down
the mountain slopes."


BTW, later on in the section, Roots specifically mentions Yves
Letocart by name, and his efforts in bringing the kagu back from the
brink of extinction.





Cheers

Tim



On Wed, Oct 26, 2011 at 3:22 AM, Jason Brougham <jaseb@amnh.org> wrote:
> The literature on the Kagu universally mentions that they glide downhill. It 
> never mentions how far. So I wrote to Yves Letocart, who is the Park 
> Supervisor at the Riviere Bleu national Park in New Caledonia. He started 
> working to conserve the birds in 1980 and is probably single handedly 
> responsible for preventing their extinction. He very graciously answered all 
> of my questions and was very helpful. He is a real hero in my opinion.
>
> He insists that Kagus do not glide. He says that they flap, both when running 
> and in short bursts of flight, such as over streams. He measured it and found 
> that, if the stream is 4 meters wide or less, the birds land on the opposite 
> bank. Any wider and they fall in the water and swim to the opposite bank.
>
> I was researching this because the Kagu has the same mass and wingspan as 
> Microraptor, and if it could glide from the ground that would really be 
> something. But the world's top expert insists it doesn't. There are a few 
> specimens in zoos. I wish we could get a  grad student to go train one and do 
> some basic measurements of its takeoff performance with a force plate and 
> whatnot.
>
> One other note from Letocart - he said Kagus roost in trees at night, more 
> often than on the ground. He said they favor sloping trees, that they walk up 
> the trunk, and that they may leap out if disturbed.
>
>
> On Oct 24, 2011, at 8:18 PM, Tim Williams wrote:
>
>> Michael Habib <MHabib@chatham.edu> wrote:
>>
>> (I've snipped Mike's explanation of feather symmetry vs asymmetry
>> solely for space considerations.  Regrettably, because his summary is
>> the most succinct and comprehensive explanation I've seen to date.)
>>
>>
>>>  In other words, high L:D wing + arboreal adaptations suggests arboreal
>>> living.  High L:D wing + terrestrial adaptations suggests terrestrial 
>>> living.  The high L:D wing is not actually that informative, because it
>>> can apply to either scenario.
>>
>>
>> Definitely.  Further, although the words "arboreal" and "terrestrial"
>> are used to describe the lifestyle of avian ancestors, what this
>> distinction boils down to is the role of gravity in the early
>> evolution of flight.  A terrestrial pro-avian could have spent no time
>> at all in trees, but nevertheless used gliding descents as part of its
>> "terrestrial" behavior.
>>
>> For example, the modern kagu (a secondarily flightless bird) uses its
>> wings for gliding while running over uneven terrain.  The Pouncing
>> Proavis model of Garner et al. (1999) proposed that pro-avians leaped
>> down onto small terrestrial prey from boulders or logs, and used
>> incipient wings to guide the descent.
>>
>> I'm not saying that either of these models are viable hypotheses for
>> incipient flight behavior.  Nevertheless, they underline the fact that
>> "terrestrial" does not automatically require that the pro-avian is
>> always fighting against gravity.  An arboreal ancestry for birds
>> strongly implies a gravity-assisted origin of flight; but a
>> terrestrial ancestry for birds is open to scenarios under which the
>> animal could either be working with or against the force of gravity.
>>
>>
>>> As a closing thought, I am extremely skeptical of WAIR ability in 
>>> Archaeopteryx, for reasons I've posted previously.
>>
>>
>> Yes, me too.  And for reasons I've posted previously (which I suspect
>> agree with the reasons Mike posted previously) the ability to execute
>> WAIR might have been beyond any non-ornithothoracean bird.  It is true
>> that young gallinaceous birds are capable of WAIR, even though their
>> wings are incipient.  But gallinaceous birds (even the young'ns) are
>> endowed with an advanced flight apparatus capable of executing a
>> complete wing stroke; non-avian theropods and basal avians/avialans
>> were not.
>>
>>
>>
>>
>>
>> Cheers
>>
>> Tim
>
> Jason Brougham
> Senior Principal Preparator
> American Museum of Natural History
> jaseb@amnh.org
> (212) 496 3544
>
>
>