ferals versus natives

To: "" <>
Subject: ferals versus natives
From: "Baxter, Chris (DEH)" <>
Date: Tue, 7 Aug 2001 16:58:48 +0930
Lawrie and Others

In response to your letter Lawrie, I would have to agree with you. However,
there is a bit more to it I reckon. Yes, the Bush Stone-curlew is quite a
common species on Kangaroo Island, perhaps more common now than at the time
of official European settlement (1836). At this time the Island was covered
in thick mallee scrub, now it is a mosaic of healthy stands of native
vegetation and open pasture. This provides a habitat scenario which appears
to be ideal for this species-somewhere to hide away during the day and
plenty of grassland/swamps/roads/beaches etc to run around and forage on at
night. Add to this a fox free environment and the Stone-curlews and other
native terrestrial species on KI are pretty much home free. Of course there
are plenty of feral moggies over there and this introduced predator must be
killing quite significant numbers of native vertebrates/invertebrates. Even
though this obviously is a major concern (and a difficult one to counter) I
believe that native species can sustain themselves quite well in the face of
such predation just so long as they still have a good habitat base to live,
shelter, feed and breed in. Without this, they soon succumb to the vagaries
of nature and introduced predators such as foxes, cats and people.

I believe the same principle applies to all species-albeit some are more
prone to predator pressure than others (eg: terrestrial species such as the
Bustard). It, I think has suffered more than most at the hands of people
hunting it since European settlement. In my job as a wildlife ranger I have
all too frequent accounts of this species being persecuted by people with
guns taking advantage of its' confiding nature. It has not got the cover to
hide that it used to either - it stands out like a sore thumb due to its
large size.

We have changed once lush tall native grasslands and understorey to a mere
skerrick of its former glory. We have altered the delicate fabric of past
ecosystems so severely it is difficult to have a real grip on just how much
native wildlife has had to adjust to survive (of which some haven't and many
others are quite quickly disappearing). So, both indigenous (and not using
traditional methods, I might add!) and non indigenous hunting of Bustards,
all too frequent burning regimes, pastoralism, widescale clearance and
radical alteration of native vegetation habitats and the introduction of
introduced predators (foxes, cats, pigs, dingoes?) and competitors ( feral:
goats, donkeys, horses, camels, deer etc) and native: (kangaroos, wallabies,
possums) have all taken a toll. These latter species are in much greater
numbers due to artificial grasslands and watering points than they ever used
to be and so add to the overall grazing pressure on native plant species.
Moreover, the Brush-tailed Possum has been identified as a major threat to
the successful breeding of the Glossy Black Cockatoo on KI as it preys on
their eggs and young!!

With my work on conservation of the Yellow-footed Rock Wallaby we found that
by getting rid of foxes the species has flourished and in one district their
numbers have increased from ca. 100 to ca. 1200 over the past 10 years. This
has been an integrated approach with goat control as well. However, I am
sure it is mainly due to 1080 baiting of foxes which has allowed the YFRW
young to survive that has been the major factor in this population
explosion. Wallaby numbers are responding even in thrashed out areas where
goats have until recently been present in many thousands.

In closing, my message is that it is not just one thing such as the fox
which is causing a species demise but a whole mix of things which put
together have changed the delicate balance of nature in Australia. On KI,
introduced American Turkeys, Peafowl, Aust. Brush Turkeys, Jungle Fowl and
even small numbers of Pheasants run wild about in the bush and prosper
(unfortunately!). This is, as Lawrie intimated, a fairly conclusive evidence
that a fox free environment goes along way towards allowing terrestrial bird
species such as the Stone-curlew to survive and flourish. Remembering also
that KI is still rich in largely undisturbed native habitats.   

Chris Baxter
Ranger, Outback Parks
National Parks and Wildlife SA
Department for Environment and Heritage

Ph:  +61 8 8648 5347
Fx:  +61 8 8648 5301

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