[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 
>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 
>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