by Tony Start, CALM WA
The Kimberley is an area of dramatic landscapes and a huge
variety of habitats which support very diverse animal and plant
communities. Quartzites, sandstones, limestones, lavas, granites
and other rocks form high plateaux and rugged ranges. But
once-mightier mountains have been eroded and transported by various
processes to form sandplains, flood plains and vast tidal mud
flats. Rock types determine both landforms and soils but water is a
key factor in the process of their formation and in determining the
distribution of fauna and flora within landscapes.
Most rain falls in humid, summer months. It is relatively high
(more than 1200 mm) and predictable in the north west but meagre
(less than 400 mm) and erratic towards the edge of the Great Sandy
Desert. In the wet, torrents rush through usually dry gorges or
down steep valleys. Some tumble straight into the sea but many feed
into huge rivers that meander through flood plains made up of the
alluvium they themselves deposited and they all recharge pools and
aquifers that sustain life through the dry season.
The frill-necked lizard is found in the
Kimberley and across northern Australia
Distribution of species
Sea and sandy deserts fringe the Kimberley savanna except to the
east where it continues through to the Victoria River District.
However, this is semi-arid country with a maximum rainfall
approaching 800 mm near the coast. Many species of the Kimberley's
more arid, central and southern savannas have continuous
distributions into the Northern Territory and often into
Queensland. Common examples are:
(To see a list of research findings on these species click on
Further north, the Cambridge Gulf now separates the
high-rainfall zones of the Top End and the north Kimberley. Most of
the species endemic to the Kimberley are found in this area.
However the occurrence of closely related species pairs and species
with isolated populations in each region indicate past links with
the plants and animals of the Top End.
Nevertheless, many more species of the far northern Northern
Territory, which has a higher rainfall, are absent from the
Kimberley than vice versa. These distribution patterns are
illustrated with birds (see table) but other groups of animals, or
plants could have been just as appropriate.
||Continuous distribution across Kimberley, Northern Territory
and Queensland savannas
||Continuous distribution across Kimberley and Northern Territory
||One species with two isolated populations, in north Kimberley
and Top End
|Two closely related species endemic to north Kimberley and Top
||Top End and Cape York but not Kimberley
* Kimberley and Northern Territory. Many species extend further
south in eastern Australia.