Re: On predation.

H. M. Hubey (hubey@pegasus.montclair.edu)
23 Oct 1995 17:56:01 -0400

j#d#.moore@canrem.com (J. Moore) writes:

>I have posted this before, but am doing so again by request; it
>outlines the general problems of predation on a transitional
>hominid population:

Thank you.

>in mental and physical abilities to chimpanzees, and so can use that
>species' proven ability to survive in open savannah woodland as a model

proven? I thought chimps were forest animals and that their main
enemy were leopards not lions, hynenas etc.

>The point is that avoiding all predation isn't what's needed, just
>avoiding *enough* predation. What "enough" is depends on how many kids

good. Like no crocs someplace.

The problem is that land predators can go anywhere where there is
land. Crocs can't travel over vast land distances and infect every
water hole or lake or river or estuary.

>What you face is not just a chimp, but a group of chimps. A group

And the group of chimps would have faced groups of lions, hyenas
and wild dogs.

The strange thing is that the South African boy with the holes
in the head seems to have been nabbed by a leopard and not
mauled by a lion. Maybe they were still hanging around forests
or else the got caught by a water hole or something.

>neither were australopithecines. In fact, even lone chimps have been
>seen sleeping overnight on the ground in areas frequented by leopards,
>which further suggests that they don't have much trouble with such
>predators.

It suggests no such thing. It may suggest that the chimp was stupid
or that it got eaten the day after.

It may also suggest the homeostatis today. i.e. a single leoapard
is no match for a group so it has already learned to give up
trying to hunt chimps. See below.

>predators. To do this, he used a stuffed leopard dummy with electrically
>moveable head and tail. A baby chimpanzee doll was placed in the

Even lions which are dumber seem to realize after a while the
difference between a real animal and a dummy. There are people
who pulled similar experiments on lions.

>tested several times, including groups in two different jungle areas,
>and a group of savannah woodland chimpanzees. All the chimp groups
^^^^^^^^^^^^^^^^^

What :-)..

>reacted by picking up sticks as clubs, breaking small trees and tree
>limbs to use as clubs, and throwing these at the leopard dummy. An
>interesting difference emerged between the jungle chimps and the
>savannah chimps. The jungle chimps, while aggressive toward the
>leopard, were uncoordinated in their attacks and when throwing objects,
>never actually hit the leopard.

Probably because they already know from experience that the only
advantage of the leopard is sneaking up on them and that they
can always scamper up trees so that there's no need to do much
except let the leopard know that he's been spotted.

>They grabbed the largest of the available clubs, which was 2.10 m long,

Largest available ?? 2.1 meter sounds like it would weigh more
than a baseball, depending on the thickness.

>and they tore down small trees of about the same length; they slashed
>viciously at the leopard with these.

Even a pack of hyenas can drive off a pride of lions if they
outnumber them and howl viciously enough. A single leopard could
be scared off, but I think we pretty much said that packs of
lions and hyenas would be a real threat.

With the aid of the film we made,
>we could measure impact velocities of approximately 90 km/h, which would
>have been sufficient to break the back of a live leopard. In addition,

Hmmm. That's 25 m/s or about 60 mi/hr. Can a baseball break human
bones like that when thrown by a pitcher? I think pitchers can
throw them close to 90 mi/hr?? Anyone know the number?

BTW, a quick calculation says that they'd be able to throw this
about the length of a football field at this speed. I'd like
to see that.

>to what we observed in the jungle chimpanzees. During the final attack
>the dummy was encircled by five chimpanzees, while two others stood in

I'd circle dummies too. I think the intelligence of the chimps
is being underestimated.

>readiness at some distance, in case they should be needed. Then the

Anthropomorphising. Some run, some stay behind, some fight.

>leader grabbed the tail of the leopard and ran away, tossing the
>predator so that the head flew from the body.

Yeah, try that with a live leopard or a lion among a whole
pride/pack of them. Indeed, they wouldn't probably stand a
chance against hyenas.

> "With that, the enemy was considered 'dead'. The apes showed no more
>fear of it, and the youngsters were allowed to touch it. The attacks on
>its head, however, continued during the whole day.

Dead but still attacking. Hmmm.. Is this science or wishful thinking.

> "A side effect of the experiment was the observation that the savannah
>chimpanzees more often walked erect than do the jungle chimpanzees."

A real scientific statement! They must have had their chests
bulging out from pride of killing a leopard :-)..

>Chimpanzees do not seem to be overly afraid of big cats; besides the

Leopards!!!

>chimps have been spotted screaming at lions (from a distance) but
>holding their ground.

What did they do afterwards :-)..

>Then there was that leopard den. A band of chimps went over to a

Did the chimps really know it was a leopard den? Just curious.

>some reason ;-). A couple of male chimps did, however, and dragged out
>one of the leopard's babies and beat it to death.

Hard to believe. Even a hen would attack under these circumstances.

Either the mommy leopard wasn't there or injured or something else
was wrong.

-- 





				Regards, Mark

				http://www.smns.montclair.edu/~hubey