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

[Dann Pigdon <dannj@alphalink.com.au>]

Larry Febo wrote:
>  
> 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...

Not always so. Whales don't head towards polar regions to avoid
predators, but to take advantage of the much richer food reserves.
In fact, if new-born whales were able to withstand polar conditions
from birth whales would probably never leave the polar regions.
Adult whales hardly eat anything (sometimes nothing at all) while
breeding in warmer waters.

As far as the arctic geese are concerned, arctic summers are very
brief so many plants grow and bloom rapidly at about the same
time, providing a sudden abundance of food that is highly predictable.
Lack of predation is probably just one of the advantages of nesting
in a polar or sub-polar region.

The cold currents that sweep the western coasts of South America
are also much more nutrient rich than the warmer El Nino currents.
Although the coast of Peru is almost sterile desert, people still lived
there in antiquity to take advantage of the rich cold ocean
currents. I believe that in warmer El Nino years, the fishing
in this part of the world is extremely poor.

Although two of the above examples concern the ocean rather than
terrestrial habitat, there are many modern-day dinosaur lineages
that also take advantage of rich polar or sub-polar ocean areas.
Penguins and albatross come to mind immediately.

-- 
____________________________________________________
        Dann Pigdon
        GIS Archaeologist
        Melbourne, Australia

        Australian Dinosaurs:
        http://www.geocities.com/capecanaveral/4459/
        http://www.alphalink.com.au/~dannj
____________________________________________________