[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Theropod "migrations"



At 11:56 AM 4/26/99 -0500, Joseph Daniel wrote:
>This is not really true. Physiologically, sure. Behaviorally, no. Almost all
>predators have a "menu" of prey items that they will hunt. Animals that
are not
>on that list are usually ignored.

In any given region this may be true, but this is often largely a *learned*
response, not an intrinsic one.  Certainly predators show a wide variation
in prey items between regions.

> Sometimes if the predator is in extremis it
>may go after something that is not normally a prey item but this is the
>exception, not the rule. People are not safe from bears in the woods not 
>because
>the bear thinks of us as food, but as competitors. Tigers and lions don't 
>make a
>habit of attacking and eating people usually until they are old and unable to
>hunt their regular prey and even then it is rare.

The way predators treat humans is NOT a good model for the general case.
We humans have this nasty habit of *killing* animals that kill, or even
merely attack, other humans.  This tends to produce a strong selective
pressure to *not* attack humans on most wild predators. 

>species. but, since they usually have more than one prey species, the 
>predators'
>ranges can be bigger than the prey species.

It has to go beyond that, as there are *zero* prey species in common
between China and central North America (or there were until humans entered
the picture).  Yet wolves lived in both places.  (And I cannot think of any
prey species that are found in common between Europe and East Africa, so
the same probably goes for the lion).

--------------
May the peace of God be with you.         sarima@ix.netcom.com