Re: MODERN BIRDS AND MIGRATION

["Matthew Troutman" <m_troutman@hotmail.com>]

>It's also likely that tradewinds will affect migratory behavior-if it's
>easier to fly long distances via a high altitude tradewind, you might
>not find migratory animals travelling out of this 'byway'.  
>You might try checking this theory if idyllic spots that are not along 
a
>byway are bypassed for those that are, even when further away.
>However in the case of fossil birds I have no idea how you would try 
>and identify mesozoic tradewinds.

This might not be applicable to bats.  This would require incipent 
soaring ability, something that in bats is only found in a species of 
totally diurnal flying fox, _Pteropus samoensis_.  The reason soaring is 
not found in bats is because they are nocturnal, and thermals are not 
especially strong during the night.  However, this can be the case of 
birds, but it still doesn't explain the motivation, which, I believe, is 
linked to the seasons, the climate within the seasons, and the food 
source during these seasons.  

Also, let me correct something in my first post on this matter.  
Ornithurine birds include all modern birds and their extinct relatives.  
I made it sound like all birds were ornithurine, this is not true since 
there were birds that lived before ornithurines and were more basal on 
the avian family tree (not as basal as _Archaeopteryx_, though).

Regards,

Matt Troutman

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