[Fwd: The Age of Modern Bird Species and Migratory Behaviour]

[Betty Cunningham <bettyc@flyinggoat.com>]

this was posted on sci.bio.paleontology.
Does enyone here on the DINOSAUR MAILING LIST have a suggestion where
this gentleman can start looking? 
He is NOT subscribed so feel free to contact him off list.
-Betty
-------------------------------------------

David Grayshan <dgrayshan@tschan-partner.com>
 Newsgroups:        sci.bio.paleontology
David Grayshan wrote:
> 
> Could anyone please help me with these questions (there is no zoology
> or ornithology group that I can find)? I need the answers for a
> discussion on another NG.
> 
> First, I am trying as a layman to establish how old bird migratory
> behaviour is. Is it as old as the modern bird species? Or might it be
> inherited behaviour from the predecessors of the modern species?
> 
> Secondly, how old are the modern species, on average? Are strongly
> migratory species, such as the Bar Tailed Godwit, importantly younger
> or older as a species than other, less strongly migratory species?
> 
> Thirdly, is it known or is there a good theory as to why birds migrate
> in the way they do? The Godwits migrate vast, distances, for example,
> from Northern Europe to New Zealand. Why so far? If it's just food or
> water there's plenty of that a lot nearer than New Zealand. Migratory
> behaviour is predictable, regular, systematic, in fact, highly
> evolved. Are there many species that travel similar distances to the
> Godwits, or are they unique?
> 
> Motivation:
> 
> I have an idea that, when this type of systematic migration started,
> the distances between the points of departure and destination were
> much closer than they are today: I am thinking of a geographical model
> of such as that of Pangea, shown on the Website "The Dynamic Earth" of
> which the address is:
> 
> http://pubs.usgs.gov/publications/text/dynamic.html#anchor19309449
> 
> But the dates given in this model are 225 million years ago for the
> start of the breakup of Pangea, the Geography of which might offer a
> feasible geographical scenario for the start of migratory behaviour.
> By the Triassic the distances between the continents might already be
> too far for such as the Godwits to discover such places as New Zealand
> 
> by accident: it seems to me that they must have established their
> migratory behaviour before such distances were a fact.
> 
> But surely: such modern bird species do not date from the Permian, or
> even the Triassic? Surely they date from much later?
> 
> So: why do birds migrate in the manner in which they in fact do? And
> when did they start to display this particular type of behaviour? And
> how do we account for the sometimes enormous distances involved?
> 
> Thankyou to anyone having the patience and taking the time to respond
> to this probably quite complex query. Feel free to respond to me
> personally if I am so off-topic that I should not be on this NG, but
> as I stated at the top, I cain't find nowhere else to go...
> 
> David.