Re: Herbivore protection

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

Stan Friesen says: "...colonial nesting *can* improve the
effectiveness  of predator satiation, by maximizing the
localization to a greater extent than the predators can match." 
He bases this on the passenger pigeon and says: "...with few
exceptions, major predators are not able to match..." the feat of
gathering all individuals "from many thousands of square miles."
     This may be true (and thank you for the example).  But it
may not be true.  For example, on what basis do they choose where
to site their mass nests?  Could they be places of relatively low
pred. density?  What were the predators?  These are the questions
I would like to answer before a full capitulation on this issue.
Also, some of your info differs from mine.  For example, I read that these
pigeons nest up in trees and not, as you say, in forest clearings.  This
limits some predators and provides an immensely greater area to hide than
ground cover.  And P. pigeons did not nest in one "spot"
unless you define a spot to be 300 sq. miles.     

But still, I don't think this example is fully applicable to
colonial nesting dinosaurs.  P. pigeons from Detroit fly to New
Jersey.  They leave all their fox, raccoon, squirrel, snake,
predators behind.  The only way a fox could make it to New Jersey
in time would be to catch a bus.  Migrating herbivorous dinosaurs
could not have such a large skill differential between themselves
and their predators as has a P. pigeon and a fox.  I know long
migrations are possible and they probably happened.  But at least
some of our modern predators move right along with the ungulate
herds.  I give in, I don't know how they protected themselves!

Stan Friesen doubts my claim that grunion exploit the high water
mark because it is a place of low predator density.  And he cites
gulls, terns, etc., as predators of this zone.  This is true.  I
meant predators of grunion _eggs_.  That is, there are more
things in the sea that will eat their eggs, presumably, than in
the sand at the high tide line.  Sorry for the misunderstanding.