It should be noted that this data is now somwhat dated!
Feral animals impact on catchment condition by added grazing pressure,
competition with native animals and by increased ground and water disturbance.
Feral animals can also host and distribute diseases such as Brucellosis and
mange. Rabbits and goats are renowned for their grazing impact, and including
pigs, can cause severe ground disturbance leading to erosion. Foxes and cats
are predatory on many native species and also transmit diseases. Buffalo cause
muddying of waterways and can harbour Brucellosis. Buffalo, horses and goats
can also assist the spread of weeds.
Feral animal density is an indicator of the extent to which Australia has been
colonised by a range of exotic fauna species. Native species numbers and
distributions have declined through direct predation, such as by foxes and
cats, overgrazing by rabbits and goats to changing habitat conditions through
competition for available resources. This issue is difficult to address at a
catchment scale due to animal mobility.
Regional/national strategies are required (eg. use of calicivirus to wipe out
rabbits). The main areas of Australia with relatively high feral animal counts
are Gippsland and the mountains of southern NSW. The Victoria River Downs (NT)
also shows with high feral animal density. Moderate to poor condition is
otherwise indicated throughout most of eastern Australia and in the north of
W and in the Northern Territory. Feral animal density is generally low in
most parts of Tasmania, South Australia, and Western Australia and in the
Riverina District of New South Wales. The ABARES/CSIRO feral animal coverages
were used, which date from the late 1980s.
The scale of mapping is 1:25M. These maps give qualitative spatial
distributions for 22 feral species. Four classes of feral animal density were
defined (high, medium, low and none) and assigned a numerical value (3, 2, 1
and 0). The density values for each species were added for all species, giving
a relative feral animal rating. Given the low resolution of the feral animal
coverages, only a broad regional picture is possible. Data reliability is
poor.
Data are available as:
See [further metadata](http://data.daff.gov.au/anrdl/metadata_files/pa_iccilr9ab
__07121axx.xml) for more detail.