From: russ@wpg.com (Russell Lawrence)
Newsgroups: talk.politics.animals
Subject: Re: Self Regulating Populations
Date: 21 Aug 92 21:38:54 GMT
Organization: WP Group


Russell Lawrence writes:
rl> Can predators self-regulate their populations?  Or, were you 
rl> thinking that their populations would also continue to grow and grow 
rl> and grow ad infinitum?  Would predators require "culling" at some 
rl> point to prevent their populations from ballooning out of control?

From article <RIGG.92Aug19121612@osnome.che.wisc.edu>, by rigg@osnome.che.wisc.edu (Tim Rigg):
tr> Okay.  Natural ecosystems can and do self regulate.  However, I am not
tr> talking about some ideal place, but rather the current conditions in
tr> America (and elsewhere I suspect).  Northern Wisconsin might be able
tr> to support other natural predators such as wolf packs and coyotes.
tr> However, the rest of the state can not.  
tr> 
tr> I'll rephase my question:   in areas without any predation (such as
tr> most of America), would deer and other prey animals self regulate?

Let me rephrase the point I made previously:  Wolves typically remove
sick and aging members of the herd.  In the process, they reduce the
threat of disease.  However, it's food supply, not predation, that 
limits total population in natural, stable environments... contrary
to a popular hunter myth.

As you say, however, we still have some major problems and the natural
regulatory mechanisms don't appear to be working.  The truth of the
matter is that the natural regulatory mechanisms are working, but
they're not working effectively because the environments are unstable.
This is especially true in your state, I believe, because of forest
management practices that bring about feasts followed by famines.  Coupled
with hunting, some of these practices actually increase fertility, and 
thereby contribute to the overpopulation problem.

tr> As for non-prey animals, I haven't read as extensively about them.  I
tr> suspect that they can self-regulate.

The evidence indicates that the underlying principles work in all mammals
and possibly birds as well.  Several days ago CNN reported that the
number of eggs laid by one particular colony of coastal birds was 
dramatically down this year because of the impact that enviromental
pollution and human fisheries have had on their food supply.  The
commentator suggested that the drop in egg production was a Bad Thing,
but the truth of the matter is that the population is already too large
given the diminishing supply of food.

rl> Getting back to the deer park that you mentioned previously, 
rl> would you say that the reserves in question were ecologically
rl> stable and free from human interference?  Were the deer that lived 
rl> therein dependent on the resources of the eco-system alone or were 
rl> their food supplies supplemented with fat-rich animal feeds and/or
rl> handouts from well-meaning visitors?  

tr> I imagine the reserves were free from human intervention.  But I also
tr> suspect that that there was no predation (by hunters or other natural
tr> predators).  It is the complete lack of predation that is the problem.

So says the hunter myth.  If you think about the myth critically, 
you'll discover that it's proponents somehow believe that natural 
predators can outmatch their quarry the way humans with guns 
might do.  The empirical evidence shows, however, that the 
defensive skills of healthy deer are a good match for the 
offensive skills of their traditional predator (wolves).  Apart 
from the empirical evidence presented by Mowat and others, the 
hunter myth falls apart logically when you ask yourself what 
prevents predators from simply killing and consuming all the 
prey.  Surely they don't take a census of the available deer and 
limit their "harvests" the way humans might do.  

In an example posted previously, Jonathan Spencer already mentioned
that the deer in one such reserve were free to extend beyond their 
designated range and subsequently encountered human crops, which are
typically high in fat and protein, and hence likely to increase 
fertility.

tr> I suspect that you are thinking, "well, let just introduce other
tr> predators and do away with this hunting business."  There are several
tr> problems with this.  First and foremost is that many areas can not
tr> support predators large enough to cull deer herds.  Mountain lions,
tr> bears, and wolf packs would have a hard time thriving in most of
tr> Wisconsin.

It seems to me that we need to stabilize these eco-systems that we
wish to preserve, and stabilization won't be possible as long as
hunter advocacy groups continue to petition lumber companies and park 
departments to maintain a large deer "harvest" from year to year.
Personally, I think it's dishonest when a group campaigns for programs
that will increase overpopulation (aka "harvests), while citing 
overpopulation as a moral excuse for sport hunting.    

tr> Another factor is that the deer cares little what predator ends its
tr> life.  I see no difference between the predation of man and that of
tr> other natural predators.

Perhaps you don't see a difference between human predation and natural
predation but those differences do, indeed, exist. 

If I'm not mistaken, the average age of deer in the United States is
less than three years, yet deer don't reach their full skeletal maturity
before five years of age.  If they were subject to natural predation
in stable ecosystems rather than human predation in contrived ecosystems, 
there would be fewer deer and they'd live quite a bit longer.

-- 
Russell Lawrence, WP Group, New Orleans (504) 443-5000
russ@wpg.com   uunet!wpg!russ
Newsgroups: talk.politics.animals