More on Mr. T (bflying in parks)

[Neil Jones]

In message <v01530501b0327137a229@[207.158.13.60]> conlan at ADNC.COM writes:
> Neil Jones wrote:
> 
> >I would
> >point out that the greater capacity for reproduction of invertebrate
> >populations is largely a red herring in this arguement.
> 
> I could not disagree with this more!  Ken Phillip already commented nicely
> on this but let me just add a couple things.  The incredible reproductive
> capacity of most invertebrates lies near the core of this argument.  It is
> this capacity which allows rapid repopulation of areas and the large
> population flux we often see in others.  Extreme predation/parasitization
> in one year can often be more than compensated for in the following year.
> I have seen populations go from virtually unseen to almost nuisance levels
> in a single year.  Does anyone honestly think most birds or mammals could
> do this (maybe some rodents)?  When was the last time a Condor, Eagle or
> Moose gave birth to 200 offspring in a season!!  If you could get 200 eggs
> out of a California Condor they could have repopulated the Western USA in
> about two years!  Invertebrates utilize a much different strategy for
> survival and often don't fit into the same old arguments people use for
> birds and mammals.
>
> Chris Conlan
> conlan at adnc.com
 

I made this posting some time ago in February 1996 if I recall correctly
and I have reposted it several times because the same point seems to be
being made continuously. It better answers points which were made at the
time it was originally posted but much of it is valid in answer to the
general point being made  by several people which seems to be
that collecting can never do any harm.



Subject:      Population change and collection/predation
From:         Neil Jones <Neil at nwjones.demon.co.uk>
Date:         1996/02/05
Message-Id:   <823548673snz at nwjones.demon.co.uk>
Newsgroups:   sci.bio.entomology.lepidoptera
[More Headers]

It has been asserted, but not proved that no insect has ever been extirpated
by human beings removing individuals from a population. It has also been
asserted that since this is the case it would be unreasonable to prevent
human beings from doing this where the insect species is in danger of
extinction. In order to validate the second statement it
is necessary to examine the question of whether the first statement can be
disproved. 

 Gathering individuals from a population could be regarded as predation
by one species on another. In this case the predator being Homo sapiens.
It is therefore necessary to examine whether a predator can affect the
population of a species.

There are numerous examples of this. For example it is well documented
that the hymenopteran parasitoid Cotesia bignelii has an effect on the 
population levels of Eurodryas aurinia. There is even an example of
an invertebrate predator foreign to an ecosystem exterminating entire species.
This has happened with several species of Partula snails on Pacific islands
which were exterminated by a foreign predatory snail.

Invertebrates do have a greater potential for population growth and recovery
than mammals or birds but this does not prove that they are necessarily more
resistant to predation. Over the long term each pair of organisms will
produce, on average, one pair of offspring during its life time. 
Insects have just as many predators as other animals. Increasing the predation
will put stress on the population and could, where the population is small,
cause an extinction.

It is logical to assume, given the evidence generally available, that the 
first assertion is liable to be proved very simply by experiment. The fact
that experimenters have failed to do so in a few examples is not conclusive.
It merely proves that there was not sufficient stress placed on the population,
not that it is imposible to do so.

 I myself have observed several populations of insects where due to the
nature of the lifecycle it would be easy to remove all the individuals. I have
not done so because it would be unethical.

 The fact that there are individuals around who will put their own
personal desires above the right of a species to exist is further evidence
to indicate that it is necessary, in the case of endangered species, to
prevent human predation in addition to conserving the habitat.



-- 
Neil Jones- Neil at nwjones.demon.co.uk "The beauty and genius of a work of art
may be reconceived, though its first material expression be destroyed; a
vanished harmony may yet again inspire the composer; but when the last
individual of a race of living things breathes no more another heaven and
another earth must pass before such a one can be again." William Beebe