the extremists

Neil Jones Neil at nwjones.demon.co.uk
Thu Jan 18 13:14:13 EST 2001


In article <000901c07f21$a719ad20$9b0f1218 at gscrk1.sc.home.com>
           gatrelle at tils-ttr.org "Ron Gatrelle" writes:
 
> Yes, I know of a couple. The bad apples that spoil the bunch. I am very
> tempted here to name one name in particular. The person lives below the
> Mason Dixon line and is fairly well known. I also admit Neil that just one
> of this type is all us pro-collecting types need to go superlative and
> build an even bigger straw man. Just as one real poacher is all the "other
> side" needs to impugn all collectors.
 
Yes. I think it is a straw man. What does concern me is that when ever there is
a case of a poacher being prosecuted he gets a lot of sympathy from
certain people here. The most obvious case was 6 or 7 years ago when one of the
poachers was on Leps-l posting psychotic drivel (or "historic postings" as
he put it) about how he had been the victim of a conspiracy.
Despite his showing signs of  mental instability (Delusions of grandeur,
 paranoia etc. ) he had people supporting his position.
I will have to dig out what I have and put it on-line. My archive for
this period is probably partly incomplete although I should have everything
I sent myself filed away.
 
>
> Neil, not only do I agree that rare species should not be collected. I am
> the rare collector who does believe that one collector can eliminate a
> local population. However, I believe this is only done by the aggressive
> collection of immatures -- e. g. Megathymus larvae and pupae.
 
There is no question that increasing predation can impact the population.
It is an absolutely standard part of population dynamics theory.
Predator not equals Homo sapiens is not written into the equations.
 
It isn't necessarily just collections of immatures. Let me give an
example. I knew a population of a checkerspot that was small (they often are)
on a protected wildlife site just a few miles from me.
Like all the species in this group it is a batch egg layer. Each female can lay
a theoretical maximum of 288 eggs in one batch on the day she emerges.
She may lay more eggs later if she can survive and feed.
 It is therefore possible to easily identify the larval web masses.
Indeed this has become the standard survey method for the species since our
climate is not always reliable in the flight season.
 
On the site in question the managment of the habitat was only just starting
and the foodplant was decining. It was actually possible to examine the
vast majority if not all of the plants to see if they had larvae on them.
I did this with a colleague and we found 2 groups of larvae. (I had actually
seen one of the egg batches being laid and marked the spot.)
*Just two* This colony was in this season reduced to a maximum of two
females. Had somebody removed those *two* butterflies the colony
would have been wiped out.
 
Now you may argue that if that colony was that small it would not survive.
Well in this case the species is known to exist in metapopulations.
Groups of populations which periodically become extinct to be recolonised
from their neighbours.
 
Many of the colonies of this species are small. In fact the majority of them
are. Finding less than 10 larval webs is very common and the species
fluctuates enormously. One site what had an enormous number (279) webs a few
years ago was down to almost single figures recently.
That high number was so exceptional that the BBC came down to do a radio
program on it.
 
The next piece of my argument is difficult to make. It would take a number
of rather complex equations to demonstrate it. Putting it simply though
It would be possible by impacting enough populations to seriously threaten
the metapopulation as a whole. In a grossly oversimplified manner
is boils down to the essence that it can be demonstrated that *in theory*
and at our *current level of knowledge* a certain number of colonies need
to exist over time in a certain area for it to be stable.
 
If you want to be certain of conserving  something you don't take chances
by increasing predation. The ecology of this *single species* is very
complicated and difficult to understand but the effect of predation
is possible to model. Ecology is complicated, which is why some of
us get frustrated when we hear people being convinced by simplistic
anecdotal and unproven "creative science".
 
There is also some evidence that smaller populations are more likely
to generate colonisers due to the "Allee Effect". It has nothing to
do with a French very but is someone's name and it is an effect where
small populations tend to loose individuals easily because they sort of
wander off.
 
 
--
Neil Jones- Neil at nwjones.demon.co.uk http://www.nwjones.demon.co.uk/
"At some point I had to stand up and be counted. Who speaks for the
butterflies?" Andrew Lees - The quotation on his memorial at Crymlyn Bog
National Nature Reserve
 
 
 
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