From: achenbac@epcot.spdc.ti.com (Jeff Achenbach)
Subject: Re: Self Regulating Populations
Organization: TI Semiconductor Process and Design Center
Date: Fri, 28 Aug 1992 15:56:35 GMT

In article <BtoHK9.G7G@wpg.com> russ@wpg.com (Russell Lawrence) writes:
>Russell Lawrence writes:
>rl> As a side-note, would you say that human diseases (AIDS, for instance)
>rl> are transmitted more slowly in small towns than in large cities, simply
>rl> because the populations are smaller?  If readers were to stop and analyze
>rl> the transmission vectors of most diseases, I think they'd come to
>rl> the conclusion that the indiscriminant culling of a given population is
>rl> *not* going to be effective in preventing the spread of disease, whereas
>rl> the culling of infected individuals alone can be quite effective.
>
>From article <1992Aug25.135218.510@spdc.ti.com>, by achenbac@epcot.spdc.ti.com (Jeff Achenbach):
>ja> Just a guess, but it would seem more likely that population density, not 
>ja> population per se, is the important variable. Diseases with only human 
>ja> vectors for transmission will obviously spread faster when interactions
>ja> are more frequent.
>
>I don't doubt that deer are social animals, and that they either seek 
>out contact with one another or avoid contact with one another in 
>accordance with their needs.  Is there any evidence to suggest 
>that the number of contacts/capita is diminished when the 
>population is indiscriminantly culled?   If not, why would we 
>believe the claim that indiscriminant and discriminant culling
>are both equally effective in reducing disease?
>

If contacts/capita remain constant, then you are saying population density
is unchanged, are you not?

>
>js> The same is true of African dogs,
>js> leopards, stoats, weasels, pike, hawks, you name it. They are all
>js> capable of taking perfectly healthy specimens of their quarry - they
>js> *have* to be.
>
>rl> Is this true?
>
>ja> Yes.  Or at least I have seen hawks, owls, and coyotes take game 
>ja> that appeared perfectly healthy.  I've spent many days afield and 
>ja> seen very few sick animals.  I have seen countless healthy ones.  
>ja> This leads me to believe that the vast majority of wild animals 
>ja> are reasonably healthy.  A coyote or wolf would be hard pressed 
>ja> to survive if it never took a healthy animal.  If you don't have 
>ja> time to go out in the woods and see for yourself, turn on the TV.  
>ja> There have been many wildlife documentaries showing predators 
>ja> hunting.  Sometimes the prey gets away, sometimes not.  There 
>ja> doesn't appear to be an overabundance of sick animals being eaten 
>ja> in these films.  
>
>As a long-distance, television observer, how can you tell whether the
>prey animals you're observing are sick or healthy?   
>

Through many first hand observations in the wild. A sick rabbit can't run
as long and fast as a healthy one. I have seen both, but admittedly few sick
ones. I presume you have seen many of the same type of wildlife shows as I.
Are you seriously saying you can't tell a starving, sick animal from a healthy
one in a good quality TV image?

>rl> Do you have any evidence to prove your conjecture that wolves are capable
>rl> of taking perfectly healthy deer?
>rl> 
>rl> Let's assume, just for the sake of argument, that your conjecture 
>rl> is true.  If wolves are capable of killing perfectly healthy 
>rl> specimens, what prevents them from simply killing all the deer?  
>rl> Do wolves conduct a deer census perhaps, and allot themselves 'x' 
>rl> number of deer per pack per annum?  
>
>ja> In most cases, wolves kill to eat. When they are satiated, they don't hunt. 
>ja> Most prey species reproduce at a higher rate than predators. When prey 
>ja> animal populations drop, a drop in predator density 
>ja> follows.  Whether adipose tissue or starvation is responsible, 
>ja> I don't know, but if prey population density (including but 
>ja> not exclusively deer) gets sufficiently low that caloric 
>ja> expenditures to capture it exceed the caloric benefit of 
>ja> eating it, predators must relocate, alter their diet, or die.  
>
>How many fawns does a doe typically produce (at most)?  How many
>pups does a female wolf produce at most?   [End of theory]
>

Deer are only one prey species. How many rabbits to the litter? How many 
pheasants, ducks, quail, grouse, woodcock, to the clutch. How many litters
of rodents and of what size are born in a year? Sorry I didn't make myself 
more clear. The species under discussion has been deer, but the predator with
the lead role in said discussion has been predominantly canines. By prey
species, I meant prey in aggregate. 

Jeff Achenbach
achenbac@epcot.spdc.ti.com
Newsgroups: talk.politics.animals