F
ORTUNATELY, THERE HAVE been successes for other species.
At Perth Zoo, for example, Peter Mawson is enthusi-
astic about the nine threatened species for which breeding
programs have produced healthy numbers. This includes the
western swamp tortoise, which might well be extinct today
were it not for the 788 bred by the zoo since 1988.
There has also been good news for the dibbler, a small car-
nivorous marsupial that lingers precariously close to extinction
in the wild: the zoo has so far turned out more than 900.
Dibblers released on two predator-free islands have done better
than those freed on the mainland.
While WA has more than a thousand other islands they
could go to, hardly any tick the right boxes – either the climate
is wrong, vegetation is unsuitable, the island is too small or
too rocky, or pythons are present. On mainland Australia
dibblers can avoid pythons but on islands they cross paths too
often. Peter can identify only a couple more islands that seem
promising.
A successful release on just one island will be a turning point
for the blue-tailed skink, which presently exists only in captivity- on Christmas Island, off Australia’s north-west coast, and at
Taronga Zoo. Introduced Asian wolf snakes ate them all on their
native Christmas Island, and the plan is to free some at a site in
the Cocos (Keeling) Islands, almost 1000 kilometres further west.
Those islands have no snakes, and no rare species that could be
eaten by the frisky little lizards.
On Lord Howe Island, off the east coast, a plan to remove
feral rats will allow the return of the Lord Howe Island phasmid,
a large stick insect presumed extinct until its rediscovery in 2001
(see AG 88). Before being taken into captive breeding at Melbourne
Zoo, the species was barely surviving on Balls Pyramid, a rocky
sea stack bursting from the sea near Lord Howe.
As for the Baw Baw frog, Deon knows of disease-free streams
that lost them due to logging damage, in gullies that have since
recovered. These could serve as release sites.
Arid Recovery has recently found that bettongs can survive
among cats. The reserve is sectioned into several fenced pad-
docks, and one of these now has bettongs living with cats,
implying that foxes are their main enemy. Because foxes are
easier than cats to control, there could be further releases of
bettongs with happier outcomes.
Arid Recovery also has new tenants to curb the bettong
crush. I am there one morning when biologist Melissa Jensen
calls on one of the 12 western quolls released in the reserve
some months before. With her radio receiver Melissa has tracked
it to a bettong warren, and we find it in a cage trap she put there
the evening before. “It’s a full house,” she says about the quoll’s
pouch; there are six pink babies inside, signalling that western
quolls – another threatened species – can prosper at Arid Recov-
ery. By eating some bettongs they should help the f lora recover,
thereby improving the habitat for a wider animal community.
Captive breeding and fenced reserves are sometimes portrayed
as panaceas, as if Australians can relax in the knowledge that
committed and clever scientists are out there saving Australia’s
wildlife. The “committed and clever” part is true, but this work
is sometimes a matter of two steps forward and one back, or
one step forward and two back.
There aren’t many jobs where you can save a species, or risk
seeing one go extinct. The people and organisations who have
taken on this work deserve our support, because Australia would
be a poorer place without them.Perth Zoo’s Peter Mawson with a western swamp
tortoise, a species that has benefited more than
most from captive breeding.Melissa Jensen releases a western quoll at Arid Recovery
where the species finds cool daytime protection from high
temperatures and predators in bettong burrows.A successful release on just one island will be a turning point for
the blue-tailed skink, which presently exists only in captivity.
AGPHOTO CREDITS, FROM LEFT: COLIN MURTY/NEWSPIX; CHRISSIE GOLDRICK
FOR MORE ON captive breeding of the Baw Baw frog at
Melbourne Zoo see australiangeographic.com.au/issue151July. August 73