Almost a quarter of our 300 or so non-flying, land-dwelling mammals create burrows for shelter, spending their lives ploughing through soil, or excavating foraging pits while searching for their dinner. These digging species come in many shapes and sizes, including some of the Rollicking Rodents (eg pebble mound mouse and hopping mouse), Magnificent Macropods (eg woylie and Gilbert’s potoroo) and the Rock Stars (eg echidnas). But here we focus on some of the quintessential digging marsupials that encapsulate the diversity and uniqueness of our beloved burrowers: the bilby, bandicoots, marsupial moles and wombats.
By quarrying for food or creating burrows, digging mammals are considered ecosystem engineers. These hard-working excavators enhance many essential ecosystem functions through the mixing of soils. Their digging actions can increase water infiltration, alter nutrient concentrations and fungal diversity, and improve seedling recruitment, all of which can influence vegetation and the structure of landscapes. This means our beloved burrowers include some incredibly important keystone species.
Their ancestral association as diggers has led to some amazing evolutionary features. All of our burrowers have developed specialised digging features – such as elongated claws – and they all have backward facing pouches to avoid covering their babies in quarried dirt!
The Beloved Burrowers can be separated into three groups based on the type of digging they perform: the sand swimmers, the architects, and the gardeners.
The mysterious marsupial moles are strictly subterranean sand swimmers who live entirely underground, preying omnivorously on invertebrate larvae, centipedes, and the occasional lizard. Due to their secretive nature, very little is known about these particularly bizarre animals. However, if their fused cervical vertebrae (that supports their neck while freestyling through the desert sands) is anything to go by, they are headstrong little critters.
Unlike the marsupial moles, whose tunnels through sand collapse immediately behind them, the architecturally inclined wombats and bilbies create warrens that are underground labyrinths, persisting in the environment for decades. Wombat warrens are so impressive they can even be seen from space. Although most of the tunnelling (up to 30m in any direction) for warrens is 1-3m below ground, they often include multiple entrances, with substantial mounds of ejected soil.
Poll for your favourite burrower here.
Read about our beautiful bats and vote for them here.
Both wombats and bilbies turn over prodigious amounts of soil: it’s been estimated a single bilby will excavate up to 30 tonnes per year as it burrows and digs for food. Their dwellings are thermally stable, providing relief from both the heat and cold extremes encountered above ground, and providing a critical refuge for many species during fire events. In fact, wombats and bilbies are generous hosts, allowing many other species to board with them, including numbats, goannas and kangaroos.
In contrast, bandicoots are surface-dwelling gardeners, digging multiple pits while fossicking for their subterranean dinner dishes of insect larvae, earthworms, fungi and tubers. As they unearth their prey, they create shallow pits up to 20cm deep as they turn over the soil. But it all adds up: the delicate eastern barred bandicoot can turnover up to 13kg of soil per night.
Similarly, the quenda (initially considered to be a subspecies of the southern brown bandicoot) exhumes close to 4 tonnes of soil each year. This activity disrupts the microhabitat layer by exposing soil at the digging site and burying organic matter and litter under the spoil heap, making a healthy population of bandicoots important for broader-scale landscape processes.
Tragically, many of the world’s digging mammals are threatened. Compared to other global regions, Oceania (especially Australia) has the highest proportion of threatened digging mammals, with nearly a third of the species considered vulnerable or extinct. If we just focus on just the digging marsupials and monotremes, this figure jumps to nearly half. Although conservation efforts for this diverse group of mammals are underway, urgent work is needed to protect and restore our unique digging mammal species.
So, when considering what mammal to vote for, think of the mysterious marsupial moles, the wise wombats, the big-eared bilbies or the bashful bandicoots – and vote for one of our Beloved Burrowers!
The nominees for most beloved burrower are:
Southern long-nosed bandicoot (Perameles nasuta), eastern Australia
During the day they sleep in nests made from grasses and other plant material, while at night these omnivores forage for invertebrates, fungi and plants.
Northern hairy-nosed wombat (Lasiorhinus krefftii), Queensland
The largest, and the rarest, of the three wombat species. When escaping a predator, wombats run into a burrow leaving their hard rump exposed, which blocks the entrance and protects their more vulnerable body areas.
Southern hairy-nosed wombat (Lasiorhinus latifrons), SA and south-east WA
Warrens used by southern hairy-nosed wombats can be more than 100 years old, and are passed down through generations.
Greater bilby (Macrotis lagotis), parts of WA, NT and QLD
They dig extensive tunnel systems with their strong forelimbs and well-developed claws. They regularly dig new burrows and can occupy up to 18 burrows at any one time.
Southern brown bandicoot (Isoodon obesulus), southern Australia
The species has a relatively short nose and ears compared to the more common long-nosed bandicoot. They have dark grey or yellowish brown fur on the upper body, tail and feet and a creamy white belly.
Shark Bay bandicoot (Perameles bougainville), WA and sanctuaries in SA and NSW
They dig so much that they help with seed growth, spread fungal spores, and aerate soils for better water filtration.
Southern marsupial mole (Notoryctes typhlops), sandy arid regions of western and central Australia
They’re the only marsupials that spend their entire lives underground, literally swimming through the sand of Australia’s arid deserts.
Eastern barred bandicoot (Perameles gunnii), Victoria
Their conical-shaped head is used in conjunction with some powerful front legs to dig crater-shaped holes in the dirt, aptly called “snout pokes”.
Polling to determine the finalists of Australian Mammal of the Year is now closed. The Top Ten finalists will be announced on Monday 15 August and final voting for the Mammal of the Year will finally begin!
Originally published by Cosmos as Beloved Burrowers – digging their way into our hearts and votes
Dr Leonie Valentine is a conservation scientist who loves wildlife and the complex interactions between species and ecosystems. She works with the Species Conservation team for WWF-Australia and dreams of a world where people can live in harmony with nature (and themselves).
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