Re: Still absent logic

[Lars_Bergquist@public.se (Lars Bergquist)]

On 95-02-12 at 00.18, Lightwaves@aol.com wrote:

> If one looks closely at the equipment a buzzard carries it will
> surprise you even less that this species can kill. (fantastic
> vision, sharp talons,  a razor sharp beak, and powerful yet graceful
> flight characteristics.)

I am not amazed. An animal does not scavenge in preference to predation
because it cannot kill, but because these tactics are more profitable *in
this ecological situation*. And, conversely. Change the ecology and
behavior will also change. (See role reversal between lions and hyaenas
in different parts of East Africa.) And even without any such general
change of circumstances, a "scavenger" will certainly kill if the
opportunity presents itself.

We all have our pet ideas. One of mine is that the behavioral range of
vertebrates--especially mammals of course, but birds too--is far
larger than you normally observe in the wild. A wild animal is always
operating under very severe  environmental constraint. Its time is
nearly completely taken up with food-searching and eating, reproduction
(at certain times of the year) and sleep. Now, give that animal shelter
and free lunches and dinners, and you will see some behavior that the
naturalist seldom observes. Wolves do not open closed doors, neither do
they fetch the morning paper. But biologically, Canis lupus and Canis
familiaris are the same species--there is no reproductive isolation.

Why does this behavioral reserve capacity exist? Because conditions
are not always stable and unchanging. An animal which has this kind
of elasticity will adapt to conditions--perhaps transient, as after some
disaster--that would kill a more rigid one. So there should exist a
selective pressure, albeit probably intermittent, in favor of it.

Then the matter of cooperative hunting again: 1) Some species do hunt
cooperatively--of course. 2) Even some raptors hunt cooperatively.
I just pointed out that in most cases, cooperative hunting *on the wing*
would not be favored, and I did cite the concrete reasons why! Now, if
it should occur (and why not?) then we would expect it to do do under
exactly the circumstances that you describe for the buzzards: A species
that has been primarily and for most of its history a scavenger, with
the typical flock behavior; a decline in the availability of carrion; and,
last but not least, wide open terrain, with no obstacles to impede aerial
manoeuvering and no place for the prey to hide.

Absolutes have very little place in the life sciences, at least above the
molecular level. The systems are too complicated, the interactions too
many, our understanding too limited. Darwin once wrote in one of his
notebooks, about species: "Never say 'higher' or 'lower'". He might
also have written: "never say 'never'--or 'always'".

Lars Bergquist
lars_bergquist@public.se
(lexicographer ... "a harmless drudge" according to Dr. Johnson,
so bear with me)

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