At 19:08 21/09/98 +1000, you wrote:
>To those out there giving sarcastic answers to my question, what ideas have
>you come up with lately to wipe out foreign species, or are you going to
>throw your hands up in the air??
>Thankyou to those who made suggestions, but does anyone have actual
>scientific knowledge of the possibility of this? I think Tony made a good
>suggestion that the resistant 1% could be exterminated by culling...if it
>worked for the Tasmanian Tiger & King Island Emu, I don't see the remaining
>1% being a problem, especially if bounties are on offer.
>PS: Why can't the same done for foxes and feral cats...bounties that is?
>email:
>
>
Dear Nigel,
If you want some serious comments, here goes...
I would suggest that the examples that you use, Tasmanian Tiger and King Island
Emus, are in no way representative of the problems caused by feral animals.
They
were both found in confined areas and both had little dealing with the
"outside world",
ie they were not as "street wise" as the Australian ferals, which have a
demonstrated
ability to survive under very tough conditions.
The combination of disease and shooting can work to eradicate ferals. The
South Africans
demonstrated this on Marion Island, a sub-Antarctic Island similar to
Australia's
Macquarie Is. Here feral cats were seriously endangering several species of
breeding
sea-birds after 5 were brought to the island in 1949 to control mice at the
Met station.
By 1977 the population was estimated to be 3400.
In March 1977 feline panleucopaenia virus (cat flu) was introduced to the
island. By 1982
cat numbers had dropped to an estimated 600. In a follow -up operation, 16
hunters shot
460 cats in 1986/87, and hunting continued for several years after and cats
are now
considered extinct on the island.
So control measures can work but several points need to be made about this.
It was an island
with no potential for the cats to reintroduce themselves. Due to its
isolation, the release
of a disease was possible [hardly likely on most of mainland Australia] and
finally the follow
up measures were very expensive and very arduous (I know several of the
people who were
involved in this project).
Marion was a very special case and certainly couldn't be used to support
general measures in
mainland Australia, except in very special isolated situations.
Bounties have very seldom worked to control animals. Many species have
density dependent
mortality which means that as their density goes down, so the survival of
the remaining
animals acutally increases (more food and territory for the survivors).
Bounties have been
in place on dingoes for many many years in Qld, etc - all thats done is
provide an income
for some rural shooters - and dingo numbers seem to flucatuate in response
to rainfall and
prey species.
I wish there was a simpler answer for the control of feral species, but I
don't think there
is. I think that all that can be done here is to work on isolated areas
that are either
natural islands, or isolated by means of fencing, etc and then remove ferals
from within that
area. Poisoning (eg 1080) can reduce predator numbers but I have concerns
about its effects
on other animals and it is no long-term solution.
Yours
Peter
Dr Peter Woodall email =
Division of Vet Pathology & Anatomy
School of Veterinary Science & An. Prod. Phone = +61 7 3365 2300
The University of Queensland Fax = +61 7 3365 1355
Brisbane, Qld, Australia 4072 WWW = http://www.uq.edu.au/~anpwooda
"hamba phezulu" (= "go higher" in isiZulu)
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