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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
>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
>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).
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