Re: MODERN BIRDS AND MIGRATION

[John Bois <jbois@umd5.umd.edu>]

On Wed, 9 Sep 1998, Matthew Troutman wrote:

> 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.  

But many if not nearly all migrations are coincident with reproduction.
The question then becomes: Are the birds using the new location's food to
"egg up"?  Or, Are the birds trying to find a place that affords some
protection from predators.  Wetlands, Arctic tundra do both of these
things.  And don't forget some species arrive to the breeding ground
already stocked up with fat reserves and don't depend so much on
available resources.

Wetlands are important reproductive havens.  This is being daily
illustrated by the excessive predation by mammals.  This predation is
often due to the increase in the amount of edge and the abilities of
predators now to broach a formerly impenetrable swamp.