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Mammal decline

There is substantial evidence of rapid declines and local extinctions of many native mammals in extensive areas of northern Australia. To read about mammal decline and workshop presentations, go to our Mammal Decline section.

Savanna Explorer > All Regions > Plants and Animals

Biodiversity of world significance

savanna flower

Brachychiton megaphyllum flower
Photo: Jean-Charles Perquin

The tropical savannas of northern Australia are important for many reasons, but one of the most notable may not be obvious to the casual visitor: the savannas are a refuge for biodiversity of world significance.

The tropical savannas are home to hundreds of species of native plants, mammals, birds, reptiles and amphibians and tens of thousands of different species of invertebrates. Many species in all these groups are found nowhere else in the world.

For information on the frogs of northern Australia, visit the comprehensive Frogwatch site (web link below). It has information on most of the northern frog species, frog calls and the latest sightings of the cane toad.

Long-tailed planigale from the Barklys Mitchell Grasslands

The tiny long-tailed planigale from the Barkly's Mitchell Grasslands. It lives in cracks in the soil, its flattened head helping it to squeeze into narrow places.
Photo: Alaric Fisher, NT DIPE

Why so many native plants and animals?

Various explanations can be put forward here. The first is that the tropics are generally found to have more biodiversity in a given area than regions in higher latitudes. The reasons for this are not straightforward but could include a number of factors: less frost; higher energy levels from more intense sunshine sustain tropical ecosystems; large areas of rainforest are found in the tropics; the tropical temperatures and humidity don't vary as much over time as they do in higher latitudes.

Dahls aquatic frog, from Yellow Waters in Kakadu National Park

Dahl's aquatic frog (Litoria dahlii ) is from Yellow Waters in Kakadu.
Photo: Martin Armstrong©

Although the tropical savannas region excludes the large areas of rainforest in North East Queensland, there are patches of rainforest scattered throughout the region. Apart from rainforest patches there are rocky gorges, arid regions, mangrove swamps, other wetlands and river habitats throughout the north. These variations in the landscape may be hidden from the visitor who generally needs to stick to the major roads—which usually avoid rock country and wetlands.

Development pressure

Clearly one factor contributing to the high biodiversity in the savannas is that significant parts of the region have not been intensively developed and still retain large areas of natural habitat.

Compared to other tropical regions in the world, Australia's tropical savannas are distinguished by sparse populations and a relatively low pressure for development. The resident population of slightly more than 400,000 is less than that for Tasmania. This figure does not include the large number of tourists that visit the region, but even allowing for this the population pressures in north Australia are very low in relative terms.

Termite mounds

Termite mounds are a conspicuous feature in the scenery of the tropical savannas. These structures range from small earthen mounds to majestic sentinel-like structures scattered across the landscape. While most people are aware of the existence of termite mounds, very few understand the significance of these invertebrates in the nutrient cycling processes of northern Australia.

Click on the "Invertebrates" link on the Navigation Bar at left, to read more of the fascinating story of Australia's termites and their mounds.