"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.

Right, so we're back to the 'non-native' judgement again.


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 ;-)

LOL, if you would thrive in them, you would seem suited to them.


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?

Removal of a species may or may not have a significant knock on effect,
adverse or beneficial, we do not know. Extinction is a fact of nature,
however.

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

Depends what you mean by 'good', I suppose. Expressing belief in the supreme
merit of the maximisation of biodiversity seems to be a tenet of faith
amongst people engaged in conservation these days.

or for potential future uses we don't yet know about?

One way I have seen suggested for putting a value on a species is to
estimate the total monetary worth of anything and everything which might be
done with it in the future. As we have no way of knowing what might be done
in the future, virtually every species can be argued to have an infinite
value on that approach. Like every premium bond might hit the jackpot, one
day, although that doesn't stop us from cashing them in for short term gain
when we feel like it :-)


And how much
importance should we place on the furry cuddly factor?

That and aesthetics? As much as we each consider appropriate, surely? After
all, it seems to be in our species' nature to modify our surroundings to
suit our own preferences. As gardeners, we do it all the time, don't we? Are
you suggesting that instead of growing things we like, we should cultivate
things we are told are 'worthy'? That'd be the day I gave up gardening.