The Mitchell Grasslands are the most extensive tussock
grasslands of Australia, stretching almost uniformly over more than
300,000 km2 from south-eastern Queensland to the
mid-north of the Northern Territory, with smaller scattered patches
extending further west to the East Kimberley and south to northern
The tiny, and endangered, Julia Creek dunnart
Photo: Greg Calvert
They form one of the most distinctive environments of northern
Australia, characterised by a general lack of tree and shrub cover,
cracking clay soils and extensive cover of relatively short
grasses. These features dictate many of the characteristics of the
fauna. The relatively simple environment ensures that vertebrate
species richness is generally remarkably low, with an absence of
most arboreal birds, and relatively little turnover in species
composition across the entire area.
Notwithstanding this general impoverishment of the fauna, there
are some highly distinctive features of the wildlife of the
Mitchell Grasslands. Several of the region's animals have an
extraordinary boom-bust population cycle, with periods of "plagues"
followed by years of very low density. The most notable of these
are the long-haired rat Rattus villosissimus, flock
bronzewing Phaps histrionica and letter-winged kite
Elanus scriptus (nb: also locusts). These population
fluctuations appear to be related to rainfall patterns, but even so
their causes are only very sketchily known.
The flock bronzewing suffered a long period of decline over much
of this century, and until recent decades, it was considered to be
heading towards extinction. However numbers appear to have built up
in many areas and flocks of hundreds or even thousands are still
reported, and are one of the most striking features of this
The cracking clay soils support a distinctive ground fauna,
notable for a very high diversity of large elapid snakes, several
endemic reptile species (such as the very large Spencer's Monitor
Varanus spenceri, the speckled brown snake
Pseudonaja guttata and Ingram's brown snake P.
ingrami), very high densities of the several grassland birds
(such as the
singing bushlark Mirafra javanica, brown songlark
Cincloramphus cruralis, and several quail) and the smallest
long-tailed planigale Planigale ingrami), and the
localised occurrence of the endangered dasyurid mammal, the
Julia Creek dunnart Sminthopsis douglasi.
Most of this fauna shelters within the cracking soil over the
course of the dry season. The rains of the wet season waterlog the
soils, and close these cracks. The wet season heralds high
densities of some burrowing frogs, and filling of the depressions
in the otherwise generally typically flat terrain. Some of these
depressions can form very extensive swamps, typically fringed by
bluebush. In many years these are nationally and internationally
significant for breeding waterbirds, such as pelicans, ibis,
herons, terns and ducks. The grasslands themselves are also a major
summering ground for some migrant birds, such as the little curlew
and oriental pratincole, whose movements are intercontinental.
There are some major conservation challenges for the fauna of
the Mitchell grasslands. Until the recent dedication of several
large National Parks in Queensland, almost all of the Mitchell
grasslands was devoted to pastoralism. This is still the case in
the Northern Territory, with the notable exception of one single
reserve, Connell's Lagoon. Several species are known to be
adversely affected by grazing, and have undoubtedly declined
substantially across this region. Conversely, the extensive
provision of artificial water sources across much of the region has
undoubtedly benefited many species, such as some macropods, crested
pigeons Ocyphaps lophotes and cockatoos.
This map of Barkly Tablelands properties shows
areas at various distances from watering points. Areas far from
watering points tend to be less exposed to heavy cattle grazing,
and consequently act as refuges for many native animals.
Effect of fire
Pastoral land management may have limited the range of fire
regimes occurring in this environment, possibly to the detriment of
some wildlife. Feral cats are now widespread, and especially common
around bores and other water sources, and are probably having some
at least localised major impacts. In parts of western Queensland,
there have been major invasions of Mitchell Grasslands by woody
weeds, notably Acacia nilotica: the biodiversity costs of
this change are not known.
Biograze: Waterpoints and WildlifeGIS procedures for regional planning;Regional planning for off-reserve conservation in rangelands;Economic costs of off-reserve conservation in rangelands;Voluntary conservation agreements; andEnvironmental Management Systems and biodiversity.
This website provides a series of fact sheets for managing the interactions between grazing and biodiversity, covering the following topics: