Posted on 30/10/2019 by Phillip Island Nature Parks
Endangered Bandicoots revealed as busy ecosystem engineers
They may be tiny, but Eastern barred bandicoots pack a punch for ecosystem health. A recently completed study of the digging behaviour of the Critically Endangered Eastern barred bandicoots on Churchill Island has demonstrated their importance in the environment by acting as ecosystem engineers and powerful earth movers.
The 2017 Honours Project, a collaboration between Phillip Island Nature Parks and Deakin University, recently published in Austral Ecology centred around questions of how much soil does an Eastern barred bandicoot dig per year and the effects of their digging activity on soil health. During data collection, the soil turnover rate of bandicoots was calculated by estimating the number of diggings a bandicoot creates per night. Physical soil properties within dug and undug soil were also tested and compared to determine the impacts bandicoot diggings.
The results were astounding and revealed that an Eastern barred bandicoot, which weighs less than one kilogram, can excavate around 500 conical shaped digs each night, turning over more than 13 kilograms of soil in its search for food like insects and worms.
“The digging rate is likely to fluctuate over seasons and across different sites, so this estimate is only directly applicable to the bandicoot population at Churchill Island over winter. They probably dig much less in summer when the soil is dry and hard,” explains Lauren Halstead, lead author of the study.
The physical properties of the soil also benefited from the bandicoot’s activities. Researchers found that their diggings break through the soil surface to expose the more porous soil and reduce compaction. This makes it easier for water to enter and remain in the soil increasing moisture content within and below the digging.
These benefits may play an important role in the agricultural industry. “Bandicoot diggings could assist pasture growth and health, reduce topsoil runoff and be an effective way to help mitigate the effects of stock trampling and soil compaction,” said Dr Duncan Sutherland, Deputy Director of Research at Phillip Island Nature Parks and one of the study’s co-authors.
Since European settlement, Australia has lost more mammal species than any other country. Six of Australia’s digging mammal species have become extinct with only 23 remaining. This is largely due to predation from invasive predators such as foxes and to loss of habitat. Eastern barred bandicoots very nearly met the same fate. The conservation introduction of Eastern barred bandicoots onto fox-free Churchill Island and Phillip Island has brought them back from the brink.
“The important role bandicoots play in ecosystem health revealed in this study demonstrates why protecting Australia’s remaining threatened species is so essential and why Phillip Island Nature Parks is committed to their recovery. On Phillip Island we are so lucky to have these ecosystem engineers back in the landscape helping to provide healthy, functioning habitat which allows other species to flourish.”
- In Victoria, Eastern barred bandicoots only occur in captivity, inside predator proof fencing or on predator free islands. To ensure the survival and assist the recovery of this species, human intervention was required.
- In 2015, a population of 20 bandicoots was released onto Churchill Island, adjacent to Phillip Island.
- Churchill Island is made up of a mixture of habitat types, including farmland and bushland.
- The founder population on Churchill Island has been reproducing successfully and the population now exceeds 120 individuals.
Roland Pick – Communications Executive
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