Post by Patrick Kubeja on Dec 13, 2004 6:16:00 GMT -5
Cane-Toad Invasion Killing off Northern Territory’s Goannas -
Yellow-Spotted Monitor. (Toad’s Possible Future Effect on Mitchell's and
Merton's Water Monitors, Freshwater Crocodiles and Fly-River Turtles Also
Noted)
Canberra Times, based on an article by Rosslyn Beeby, Research,
Conservation and Science Reporter , original printed 12/10/04
The University of Canberra ecologist Dr Sean Doody thinks that the
recent spread of cane toads into the Northern Territory has caused a
massive decline in a goanna species found along the Daly River, south- west
of Darwin. He said ''Just in the last year, there's been a 77 per cent
decline in yellow- spotted monitors”. During a recent research trip, he
found populations of the big yellow- spotted reptiles (also known in
some areas of Australia as sand goannas) had dropped noticeably,
particularly along riverbanks where cane toads were numerous. He also found a
number of dead goannas. '' Goannas were still dying when we left, so the
figure could go even higher,'' he said. ''They often eat frogs, so they
see these big toads hopping along the riverbank, run them down, eat
them and die from the poison.''
Dr Doody had been studying pig- nosed turtles in the Daly River, and
was able to confirm the goanna decline from a corresponding drop in
turtle-egg predation. ''We count the eggs, and the goannas normally take up
to 20 per cent. That's dropped to zero this year.''
He also found a cane toad in the stomach of a dead freshwater
crocodile.
''It's too early to speculate on how crocodiles might be affected.
''We're only working with preliminary results, but it certainly doesn't
look good for the goannas. ''The toads haven't bred to the stage where
there will be lots of little toads along the water's edge. That will take
another year or two, and then we could see similar impacts on other
species.'' Two other Daly River goannas, Mitchell's and Merton's water
monitors, feed on frogs found along the water's edge and could be affected
once the cane toads increased.
CSIRO Sustainable Ecosystems is working on a biological-control method
that involves splicing a gene to block metamorphosis, preventing
tadpoles turning into cane toads.
Meanwhile, the Northern Territory Government has launched a national
competition to invent a cane-toad trap. The competition has two
categories - a winning trap and a fail-proof method for attracting toads. The
winner would receive $10,000 and an additional $5000 to market the toad
trap. Dr Doody dismissed the competition as ''a complete waste of
time''. Northern Territory Parks staff had also voiced doubts that traps
would solve the cane-toad crisis.
However, Brisbane's crows may prove to be a more effective deterrent.
Dr Doody said the wily birds appeared to have developed a method of
killing and eating toads, without exposing themselves to the deadly toxins.
''We're not sure yet how them kill them but they seem to somehow turn
the toad inside out to eat it.''
Yellow-Spotted Monitor. (Toad’s Possible Future Effect on Mitchell's and
Merton's Water Monitors, Freshwater Crocodiles and Fly-River Turtles Also
Noted)
Canberra Times, based on an article by Rosslyn Beeby, Research,
Conservation and Science Reporter , original printed 12/10/04
The University of Canberra ecologist Dr Sean Doody thinks that the
recent spread of cane toads into the Northern Territory has caused a
massive decline in a goanna species found along the Daly River, south- west
of Darwin. He said ''Just in the last year, there's been a 77 per cent
decline in yellow- spotted monitors”. During a recent research trip, he
found populations of the big yellow- spotted reptiles (also known in
some areas of Australia as sand goannas) had dropped noticeably,
particularly along riverbanks where cane toads were numerous. He also found a
number of dead goannas. '' Goannas were still dying when we left, so the
figure could go even higher,'' he said. ''They often eat frogs, so they
see these big toads hopping along the riverbank, run them down, eat
them and die from the poison.''
Dr Doody had been studying pig- nosed turtles in the Daly River, and
was able to confirm the goanna decline from a corresponding drop in
turtle-egg predation. ''We count the eggs, and the goannas normally take up
to 20 per cent. That's dropped to zero this year.''
He also found a cane toad in the stomach of a dead freshwater
crocodile.
''It's too early to speculate on how crocodiles might be affected.
''We're only working with preliminary results, but it certainly doesn't
look good for the goannas. ''The toads haven't bred to the stage where
there will be lots of little toads along the water's edge. That will take
another year or two, and then we could see similar impacts on other
species.'' Two other Daly River goannas, Mitchell's and Merton's water
monitors, feed on frogs found along the water's edge and could be affected
once the cane toads increased.
CSIRO Sustainable Ecosystems is working on a biological-control method
that involves splicing a gene to block metamorphosis, preventing
tadpoles turning into cane toads.
Meanwhile, the Northern Territory Government has launched a national
competition to invent a cane-toad trap. The competition has two
categories - a winning trap and a fail-proof method for attracting toads. The
winner would receive $10,000 and an additional $5000 to market the toad
trap. Dr Doody dismissed the competition as ''a complete waste of
time''. Northern Territory Parks staff had also voiced doubts that traps
would solve the cane-toad crisis.
However, Brisbane's crows may prove to be a more effective deterrent.
Dr Doody said the wily birds appeared to have developed a method of
killing and eating toads, without exposing themselves to the deadly toxins.
''We're not sure yet how them kill them but they seem to somehow turn
the toad inside out to eat it.''
HerpDigest - Volume # 5 Issue # 17
Sunday, December 12, 2004
Allen Salzberg -- Publisher/Editor
Sunday, December 12, 2004
Allen Salzberg -- Publisher/Editor
