Re: Hadrosaur nesting strategy...(was Re: The Life of Birds- Pa

[Betty Cunningham <bettyc@flyinggoat.com>]

I've just recently heard about one of the hummingbirds (either Anna's or
Rufous) that migrates from Alaska to Mexico and back.  It would seem
birds migrate in and out of the tropics at all levels.  The Mexican
Free-tail bat also migrates from Canada to Mexico.  There are predators
all along the routes for hummingbirds and bats, both warm-blooded and
cold-blooded.  Doesn't seem to stop migrations as a rule.

-Betty

Larry Febo wrote:
> 
> ----- Original Message -----
> From: <B.Dol@skn.sc.philips.com>
> To: <larryf@capital.net>
> Cc: <dinosaur@usc.edu>
> Sent: Wednesday, July 28, 1999 10:19 AM
> Subject: Re: Hadrosaur nesting strategy...(was Re: The Life of Birds- Pa
> 
> > So wouldn't it be more logical to assume that the reasons for
> > migration are not avoiding predators, because in another area there
> > will always be other predators...maybe not that many or directly
> > threatening, but they could in time evolve that way.
> > Just a thought.

> It was suggested to me (offlist) that more abundance of food was the reason
> for bird migration. I thought food was always much more abundant in the
> tropics, and therefore the ability to brood in a colder enviorn as
> protection from cold-blooded predators would be the determining factor in
> bird migration. Then again, not all birds migrate. How do the tropical
> variety cope (with predators)?

-- 
Flying Goat Graphics
http://www.flyinggoat.com
(Society of Vertebrate Paleontology member)
-------------------------------------------<,D,><