From: viking@iastate.edu (Dan Sorenson)
Subject: Re: Closure on Sport Hunting.
Organization: Iowa State University, Ames IA
Date: Sun, 23 Aug 1992 02:46:31 GMT

In <BtDH94.5LE@wpg.com> russ@wpg.com (Russell Lawrence) writes:

>From article <viking.714445675@vincent1.iastate.edu>, by viking@iastate.edu (Dan Sorenson):

>We seem to be nearing agreement.  I'm going to make a few more 
>points, and then I'm going to once again suggest that we make an 
>effort to find real data that would enable us to plot some 
>meaningful curves.  Otherwise, we'll just end up spewing hot air 
>instead of raising our level of understanding.  

	If you wish to have me collaborate on this, e-mail me with some
pointeres or request.  I don't have loads of time to spend on it, but I
am quite willing to help as best I can.  Can we make this sort of a group
project, with you as team leader?  I suspect others may wish to e-mail
you with their willingness to help.

>As far as habitat goes, the question that we must ask is whether or
>not it's stable.   It doesn't matter whether the area typically has
>lots of food or very little food, since the concept of over-population 
>is measured by calories/capita and not by the abstract measurement of
>animals/hectare.  If the area is a desert, the population may be small
>indeed; if it's a lush jungle, it may be loaded with animals.  In 
>both cases, the level of body fat will determine fertility, and hence,
>stabilize the population to suit the available food.

	That works fine in a desert or jungle, where the level of food
may stay somewhat constant nearly year round.  Here in Iowa, it does
some major fluxuations.  This is caused by climate, not just growing
loads of corn that the deer love to munch on.  Again, I'd say we are
faced with having to take this generalization you've made and apply
it to different habitat on a per-habitat basis.  There are just too
many differences in habitat based on climate to do otherwise.

>If we were plotting calories/capita on a one year graph with 365 
>ticks, it would be tempting to assume that winter is a time of 
>radical instability.  Yet, "nature" anticipates this particular
>kind of instability in a big way, and has endowed us with a 
>number of compensating features and abilities.

	Indeed.  A side note: the ring-necked pheasant is not native
the USA.  It was actually brought from China some 200 years ago.  They
are doing quite well over here.  Isn't it amazing how well nature
allows for these changes?  Granted, my 12ga is a change nature has
not protected them against, and the one that tried to bluster in
front of the combine last fall and wound up being part of the corn
harvest when he jumped into the head seems to have been failed by
nature in some way, but all in all I'm impressed.

These fat reserves are _not_ inconsequential.  A 200 
>pound animal with 15% body fat would be carrying a caloric 
>reserve amounting to nearly 123,000 calories!  Third, most 
>mammals (perhap all mammals) have the ability to lower their 
>metabolism to an amazing degree when food supplies are at their 
>lowest.  As metabolism drops, 123,000 calories can last quite a 
>long time. 

	How long is the big question.  Is it long enough to survive?
In addition, we need to be worried about the times of plenty being
plentiful enough to allow building up those fat reserves.

>rl> I think both of us should do some more research to get a better 
>rl> idea of the food calories available in normal deer "food", and 
>rl> then try to get a better grip on caloric expenditures on a 
>rl> season-by-season basis.  

	More is needed.  Not only the calories available, but how
easily available (spending 600 calories to forage for 601 is what
I'm after discovering here).  Plus, how much of what's available in
the summer is going to actually be injested?  Lush, tall grass that
is ignored by the deer should also be ignored by the research.  After
all, I wouldn't count the calories at the meat counter against how
much it takes you keep you healthy. ;-)

>ds>I don't see where the
>ds> caloric expenditures are relevant unless one knows exactly how many
>ds> calories the habitat can provide per critter.  Since this cannot be
>ds> known with any degree of accurracy outside of a small field or where
>ds> crops are grown, I'd say we've got a problem.  

>Again, it isn't total caloric yield that matters, but unnatural
>fluctuations in the caloric yield.

	But we still have to find caloric yield, which it seems will be
a problem to do with any degree of accurracy.  How many caliries a deer
needs is easy, but how many he can find is hard.

>ds> Still, as time went on we had to
>ds> switch to higher-calorie foods and more of it to keep the herd at
>ds> the same (or similar) bodyfat.  I'd say the extrapolation of this
>ds> data just shows that unless the habitat is incapable of providing
>ds> less than what the herd needs, it will have its limits pushed, and
>ds> that pushing may result in fewer births or starvation depending
>ds> upon the number of other deaths in the herd and the time frame
>ds> during which the habitat is depleted.

>I don't think you can extrapolate from captive cows for several reasons:

>1) their diets are far, far higher in protein and fat than the diets
>   of wild deer.  

	Not by much.  These were not cattle being prepared for
market, they were cattle being kept as breeding stock.  Feeding them
the same diet as those who were to be shipped would be too costly.
These I refer to eat what they can forage until the habitat won't
support them, at which time we suppliment their foraging.  We're not
trying to put on weight, just keep them healthy.  Their diet is a
known quantity, and thus the results can be adjusted to reflect this.
The "big picture" here should be quite similar to deer, elk, or whatever.

>2) they're largely sedentary which increases their ability to store
>   fat while decreasing their ability to effectively use the fat in
>   time of famine.

	Agreed, and I don't know that this can be adjusted for.  We've
bred them far beyond the Cape Buffalo they may be related to.

>3) it seems unreasonable to measure the level of "starvation" 
>   in an animal by the palatability of its flesh.

	Again, they weren't for eating, and I've never measured by such
a standard.  Palatability doesn't enter into the measurement, but it
does make a big difference on how much interest I take in the situation.

<Dan Sorenson, DoD #1066 |"There'll be angels on Ariels in leather>
<z1dan@exnet.iastate.edu | and chrome, Ridin' down from heaven    >
<viking@iastate.edu      | just to carry me home." -- R. Thompson >
< ISU thinks I need more education, which they provide for a fee. >

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