On 24 Jul 1996 22:53:12 EDT, pdd@gcc.cc.md.us wrote:
>GR>After posting my last response, I thought that a better test of the
>GR>hypothesis posed in your original post would be to introduce a predator
>GR>into a community and observe whether there is in fact an increase in
>GR>diversity of the prey species.
>
>GR>There is a good test going on now. In Australia, germ warfare has been
>GR>inflicted on the rabbits. What do rabbits eat down there? And look for a
>GR>decrease in diversity of the plants they eat if the rabbits don't recover
>GR>from this epidemic.
PD>I have also heard something in this regard. From what I can
>recall the germs aren't winning and the few surviving rabbits are
>conducting a second offensive, and they ain't eating k-rations.
>Does anyone else have some info on this one?
There is a web page from the Western Australian Dept. of
Agriculture on the Rabbit Calicivirus Disease (RCD) at
http://www.agric.wa.gov.au/bunnies/rcd.html
I am attaching an extract from one of their handouts.
The virus was always only expected to kill 90% of rabbits. My
understanding is that it is proving highly successful and there
is no "second offensive" by 'the few surviving rabbits". Sounds
like a bit of US Wild West folklore? :-)
The web page confirms this:
--------------------------------------------------------
Rabbit calicivirus alone is not the answer to the rabbit problem. It
is part of a suite of techniques that together can reduce the rabbit
population to managable proportions. The best way for landholders to
take advantage of any RCD outbreak is by a follow-up rabbit control
program. Use:-
Conventional poisoning, preferably with 0ne-shot 1080 *
Warren ripping
Fumigation of burrows
--------------------------------------------------------
*NOTE: 1080 is a name for Sodium Fluouroacetate (sp?). It is a
substance found in Western Australian native plants only (argument
for biogeography <g>) and WA native animals are imune from it
(argument for natural selection adaptation <g>). It is highly toxic
to introduced species like foxes and feral cats.
Also of interest is this extract from the web page:
--------------------------------------------------------
Once rabbits start to succumb to RCD, foxes and feral cats that prey
on rabbits will go hungry. Rabbit populations normally peak and
trough, so this is nothing new, however the population should not
return to its original level, at least for several years.
Populations of feral predators will fall and probably restabilize at
a lower level, however in the early stages foxes may travel long
distances in search of food.
--------------------------------------------------------
Farmers better lock up their chickens! :-)
WA Agriculture Dept. handout follows:
=========================================================
Background
Rabbits were introduced into Australia from England in 1859 by game
enthusiast Thomas Austin, to provide an animal which could be hunted
for sport. They were able to quickly exploit local habitats and
within a short time were found in almost all areas of the continent.
Rabbits, possessing no natural predators in Australia, were able to
breed very quickly and to adapt to a variety of local environments.
By the end of the 19th century it was obvious that the rabbits had
outgrown their niche and were in plague proportions.
Does (females) can have up to seven litters per year of five or more
kittens (young rabbits). It was estimated that by 1995 there were
over 300 million rabbits in Australia. Their preference for tasty
shoots and seedlings prevents the regeneration of native flora and
encourages the consolidation of imported weeds, many of which are
unsuitable as food for native fauna. The extensive burrows promote
rapid soil erosion.
However, while the impact of rabbits upon native species is of
concern, their massive detrimental impact upon agricultural land
remains a greater cause for alarm. It is estimated that rabbits cost
Australian agriculture around $500 million per annum in damage and
lost production.
There have been many attempts to eradicate rabbits in Australia using
methods as varied as baiting, shooting, ripping of warrens and the
introduction of the disease myxomatosis. Despite limited local
success, no one method has proven to be cheap and reliable enough to
blunt the impact of the rabbit.
The Rabbit Calicivirus
The CSIRO (Commonwealth Scientific and Industrial Research
Organisation) had high hopes for a form of bio-control. Ten years
ago their attention was drawn to the rabbit calicivirus (known
internationally as rabbit haemorrhagic disease) which was found to be
naturally occurring in rabbit populations as far apart as China and
Europe. In each case its arrival had a dramatic impact upon rabbit
numbers.
The disease is highly contagious, kills quickly and has death rates
in rabbit populations of around 90%. Death comes from blood clots in
the major organs. The CSIRO were excited about the prospect of
introducing the calicivirus into Australia. If such a kill rate
could be achieved it was thought possible that traditional methods of
eradication could deal with the remaining 10%.
Escape from Wardang Island
Mindful of the potential problems associated with the introduction of
an untested virus into a delicate ecosystem, the CSIRO established a
quarantine station on tiny Wardang Island off the coast of South
Australia. Tests were needed to prove that the virus could not
spread to other species. Wardang was deemed to be suitable as it was
relatively isolated, small and overrun by rabbits. Tests commenced
on the island in March 1995. Initial results were excellent and it
was announced that after further extensive testing a national
coordinated release would come in 1998.
In October 1995 the security of the quarantine station was breached.
The virus escaped from Wardang and spread to the mainland. Despite
assurances of containment it proved to be impossible to prevent the
spread of the disease. Various methods of distribution were
investigated but none confirmed. Speculation abounded that the
spread was encouraged by farmers who wanted a rapid solution to their
problems and who were prepared to pay for rabbit carcasses to infect
their own populations.
Within weeks the virus had spread hundreds of kilometres from Wardang
and was to be found in the Flinders Ranges and Yunta. Within months
it was reported in Queensland, New South Wales and Victoria. While
most people engaged in primary industry were delighted to see the
spread of the disease there were some casualities. Almost
immediately sales of rabbit meat ceased as the public became wary
about possible infection, and many shooters and meat processors lost
their jobs.
A Dilemma
A coordinated response was called for by state governments. They
wanted to take advantage of the opportunity that existed to make a
big impact on rabbit numbers. A simultaneous release of the virus
across the continent was popular in many farming areas. There were
also voices of caution who pointed out that the disease did not kill
rabbits younger than eight weeks old, and that if it was not
introduced at the correct time, it would have a limited impact in the
long term. While it appeared to kill around 90% of rabbits in the
Flinders Rangers it was still necessary for farmers to be prepared to
use traditional methods to eradicate the other 10%. This would
entail an expense many were not prepared for at this time.
By the end of March 1996, despite the spread of the virus, there has
been no national response from the Federal Government. Many
agriculturalists are keen to make the best of the situation and
believe that April is the month best suited for a national release,
as it sees the maximum rabbit population. The CSIRO is reluctant to
condone the early release of the virus until the field trials are
finished. There are plans to convene a meeting of environmental and
agricultural bodies across the nation.
=========================================================
God bless.
Steve
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| Stephen E (Steve) Jones ,--_|\ sejones@ibm.net |
| 3 Hawker Avenue / Oz \ Steve.Jones@health.wa.gov.au |
| Warwick 6024 ->*_,--\_/ Phone +61 9 448 7439 (These are |
| Perth, West Australia v my opinions, not my employer's) |
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