By Dr Alexandra James, Senior Wildlife Ecologist
The decline of the Northern Brown Bandicoot is being reversed at AWC’s Mornington Wildlife Sanctuary in central Kimberley. Numbers have increased from no sightings in the 10 years leading up to 2012 to sightings at more than seven known sites in 2018.
This increase has occurred against a recent backdrop of declines in areas of northern Australia that were considered strongholds for this ground-dwelling marsupial. For example, Bandicoots have suffered a 90 per cent decrease in trap success on Melville Island from 2000-2015, and similar declines in Kakadu over the same period.
Data suggests that AWC’s 14 years of active land management (destocking and fire management) at Mornington contributed to this steady increase. Studies have shown that infrequent low-intensity fires, similar to what AWC achieves through the Ecofire program, provide optimal habitat for Bandicoots.
AWC’s Ecofire program (Australia’s largest non-government fire program) is an annual prescribed burning program across three million hectares of the Kimberley, during which a series of fires are lit early in the dry season when there is an abundance of moisture in the vegetation, minimising the intensity of the fire. This creates a mosaic of burnt and unburnt areas across the landscape, and reduces the risk of late-season, high-intensity wildfires, which have been linked to declines in Bandicoot populations.
Also, despite a high reproductive rate, Bandicoot populations can take many years to recover from late dry season wildfires. This is due to a need for understorey vegetation for nesting and daytime refuges, as well as for protection from predators.
More than half of Australia’s Bandicoot species have become extinct or threatened since European colonisation, making them a key indicator species that are monitored as part of AWC’s ecological health program.
The Northern Brown Bandicoot (Isoodon macrourus) is common on the east coast of Australia, north from the Hawkesbury River up to the tip of Cape York, and extending west in the higher rainfall zones into the Kimberley.
Nocturnal and solitary creatures, they are Australia’s largest Bandicoots. During the day they remain hidden in nests within the ground litter, emerging after dark in search of food including insects, fruits and other plant materials which they obtain by digging small conical holes. Northern Brown Bandicoots were detected in the isolated Phillips Range during the first survey at AWC’s Marion Downs Wildlife Sanctuary in 2009, and have since been found in Phillips Range during every annual fauna survey.
Northern Brown Bandicoots were not detected on Mornington until 2012, when they showed up on a camera trap near Annie Creek, close to the Wilderness Camp. Other small mammals, such as the Pale Field Rat, showed a much quicker positive response once cattle were removed in 2004 and early season burning began in 2007.
Bandicoots were then detected at two of our annual fauna survey sites in the same year, and at different sites each year from 2015 to 2018, bringing the total number of sites to seven. Some of these fauna sites had been trapped for more than a decade, totalling more than 6,400 cage trap nights before trapping our first Bandicoot.
The Bandicoots have now been detected on Tableland Wildlife Sanctuary, and at new sites on Marion Downs. Furthermore, the annual fauna survey sites in Phillips Range, where we first detected Bandicoots in 2009, this year showed a record number of 17 Bandicoots trapped. While some of the detections further afield point to our increased ability to detect Bandicoots using camera trapping, taken together these results point to a measurable recovery in our Northern Brown Bandicoot populations on our southern Kimberley sanctuaries. After 10 years of burning and feral herbivore removal, this recent increase in Northern Brown Bandicoots demonstrates management programs are providing improvements in ecological health that have allowed for a comeback of one of our largest ground dwelling mammals.