"Kay" wrote in message
...
In article , BAC
writes

"Kay" wrote in message
...
In article , Franz Heymann
notfranz.
writes


It would be unwise for a pragmatist like me to say yes or no to
such a
possible false generalisation.
There are circumstances where I would be prepared to participate
in
the eradication of some species in certain places for the sake
of
humans, or domesticated animals, for example

Prickly pears for the sake of grazing field
The common cold virus
Malaria-carrying mosquitoes
Bracken in the Lake District
Hedgehogs in N Uist and Benbecula
Cats on Marion Island

Well, out of that lot, nos 1, 5 and 6 could be regarded as
putting
things right after introduction of species to places where they
don't
belong,

What do you mean by 'places where they don't belong'?

They didn't get there without human intervention.

Pretty obviously, they
are well suited to those places,

I can think of many places where I would thrive, but where I don't
belong ;-)

and 5 and 6 are not primarily 'for the sake of humans or
domesticated animals' - indeed, it was the *introduction* of
hedgehogs
that was 'for the sake of humans'.

The extermination of the hedgehogs is for the sake of humans, too.
It is for
the sake of those humans who consider the continued presence on the
islands
of large breeding populations of certain species of birds to be
important,
and who believe that management of the hedgehog population is
therefore a
necessary expedient. If the presence of the hedgehogs merely
threatened the
survival on the islands of something to which humans assigned
little
importance (like the slugs they were reputedly imported to
control), I
doubt whether the RSPB or the local tourist industry would have
lobbied SNH
for their removal.

OK, a fair point.


And no 2 is an interesting one ... where do we draw the line ..
how do
we regard viruses, compared with plants, animals, fungi, bacteria
....



I suggest that similar principles apply - if a virus or any other
organism
is perceived as a threat/nuisance, countermeasures are likely to be
taken up
to the point where the cost/effort/hassle involved starts to
outweigh the
anticipated benefits.

That leaves questions about what are the benefits. Will removal of
one
species (whatever it is) have a knock on effect on others?

You have a point. I mentioned the use of Cactoblastis cactorum to
clear the prickly pears out of the Little Karoo. After the job was
done, there were rumours floating around that the insect had started
turning its atention to pumpkin fields. I don't know whether that
threat ever materialised.

Is it good to
maintain as large a number of species as possible for its own sake?
...

Yes, if you would substitute something else for "possible", such as
"feasible without harming the human population"

or for potential future uses we don't yet know about? And how much
importance should we place on the furry cuddly factor?

Very many mammalian species do in fact play an important role in the
psychological well-being of humans.

Franz