Gilbert’s potoroo (Potorous gilbertii) holds the titles for Australia’s most endangered marsupial and the rarest marsupial in the world – and it’s not had an easy time since it was first described in the 19th century.
The first specimen of Gilbert’s potoroo was collected in 1840 by John Gilbert, but it was believed to be extinct for much of the 20th century. It was rediscovered in 1994 in Two Peoples Bay Nature Reserve, Western Australia, by Elizabeth Sinclair.
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The Two Peoples Bay population is the only natural population of this animal – but it was reduced by a large bushfire in 2015. It not only killed most of the potoroos living there but also destroyed 90 per cent of their habitat.
Translocation – moving organisms from one location to another to create insurance populations – has played a large part in conservation efforts of the Gilbert’s potoroo since 2005.
Some were successful, such as a translocation to Bald Island, a fenced enclosure at Waychinicup National Park and Middle Island. Others were not: at Mermaid Point, the potoroos were preyed on by foxes, and the emergency translocation to Michaelmas Island after the 2015 bushfire failed due to inadequate food resources on the island.
The potoroo is almost entirely dependent on a single food source that’s notoriously difficult to study – fungi. This makes it a particularly tricky animal to find a suitable environment for.
But now, scientists at Edith Cowan University (ECU) and the Department of Biodiversity, Conservation and Attractions (DBCA) in Australia have used environmental DNA (eDNA) metabarcoding on the potoroo’s faeces samples.
“Fungi-eating mammal diets are quite hard to study because a lot of fungi remain undescribed,” says Rebecca Quah, who worked on the study as part of their PhD in ECU’s School of Science.
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eDNA metabarcoding scat is a non-invasive way of studying an animal’s diet. And it’s not only Gilbert’s potoroo’s poop the scientists studied – they also looked into the diets of species that historically shared the same habitats and have overlapping diets.
Bringing back the potoroo
“We examined quokka, quenda and bush rat scats and found that there was some overlap in the diet of the four mammals, and that habitat use between the quokka and potoroo were also really similar,” explains Quah.
“Based on our results, we recommend focusing [future translocations] on areas where all three species persist together as an indicator of suitable food, or habitat, for future potoroo translocation sites.”
Tony Friend, a research associate at the DBCA, has indicated that researchers are searching for a suitable mainland site to establish an additional population of the marsupial.
“The search for new translocation sites is an important next step in the recovery of Gilbert’s potoroo from near extinction. This publication shows that examining the fungal diet of mammals that occur with the potoroo can help in deciding where to establish new populations,” he explains.
Fungi-eating mammals like the potoroo have two important functions within an ecosystem. Firstly, when they dig in the soil to find fungi, they contribute to soil turnover. Secondly, when ingesting and excreting fungi, they deliver spores across the landscape, helping the fungi to grow in new places.
Fungi are important ecosystem engineers themselves, which means the animals that eat fungi are critical to these healthy ecosystems.
Read the full research paper here: Gilbert’s Potoroo and the fun-guys: Co-existing mycophagous mammals as indicators of potentially available fungal food resources
