Nullarbor dwarf bettong

The Nullarbor dwarf bettong (Bettongia pusilla) is a small marsupial belonging to the order Diprotodontia and the family Potoroidae. Endemic to the arid interior of southern Australia, its core distribution encompasses the Nullarbor Plain, the Eyre Peninsula, and scattered mallee‑shrubland fragments of western Victoria and South Australia. It inhabits dry sclerophyll woodlands, spinifex grasslands and low‑shrub mallee, where loose, sandy soils support the underground fungal networks that form the bulk of its diet. Adults weigh less than a kilogram and possess a compact body, elongated hind limbs, and a long, prehensile tail that aids balance when leaping among sparse vegetation. The species is nocturnal and largely solitary, retreating to shallow burrows or dense cover during daylight. Reproductive output is low, with females typically raising a single joey each year, making populations vulnerable to external pressures. The IUCN classifies the Nullarbor dwarf bettong as Vulnerable, reflecting a declining trend driven by introduced predators, habitat modification, and altered fire regimes. Conservation programmes focus on predator‑control, habitat restoration, and monitoring of remaining subpopulations to prevent further loss.

Nullarbor dwarf bettongs are primarily nocturnal foragers that emerge at dusk to search for fungal fruiting bodies, seeds and insects. They are largely solitary, with adult males maintaining overlapping home ranges that intersect those of several females; occasional loose aggregations form around abundant food patches. Territories are modest, typically 2–4 ha for females and up to 6 ha for males, and are defended through scent‑marking using glandular secretions from the chest and hind feet. Vocal communication is limited to soft hisses and clucks exchanged during brief encounters or when a mother calls her pouch young. Burrows are shallow depressions in soft sand, often reinforced with leaf litter, providing daytime refuge from predators and extreme temperatures. Seasonal rainfall influences activity patterns, with bettongs increasing foraging distance during dry periods to locate sufficient fungal resources.

The Nullarbor dwarf bettong is a specialized mycophagous omnivore, relying heavily on the sporocarps of subterranean fungi such as species of the genera Cortinarius, Laccaria and Russula. Fungal fruiting bodies can constitute up to 70 % of its dry matter intake during peak seasons. Complementary foods include seeds of native grasses, tubers of Triodia spinifex, and occasional arthropods like beetles and termites, providing essential protein and minerals. Individuals forage by sniffing the soil surface and using their elongated snout to excavate shallow patches where fungal mycelia are abundant. Daily intake averages 150–200 g of dry matter, and water needs are largely met through the moisture content of fungi and succulent plant parts, reducing dependence on free water sources. Seasonal scarcity of fungi prompts longer foraging trips and increased use of cached food stores beneath leaf litter.

Females reach sexual maturity at about 10–12 months and typically breed once per year during the austral spring (September–November). After a brief gestation of 21 days, a single joey is born and immediately crawls into the mother’s pouch, where it attaches to a teat and continues development for roughly 70 days. The young remain in the pouch until they are furred and capable of thermoregulation, after which they are left in a nest while the mother forages, returning to nurse for another 4–6 weeks. Weaning is completed by 4 months of age, and juveniles become independent by 6–7 months. Litter size never exceeds two, and reproductive success is closely tied to the availability of underground fungi, which can fluctuate dramatically with fire and drought.

The IUCN Red List classifies the Nullarbor dwarf bettong as Vulnerable, with an estimated total population of fewer than 10 000 mature individuals and a continuing decline of roughly 20 % over the past three generations. The principal threats are predation by introduced red foxes (Vulpes vulpes) and feral cats (Felis catus), which exploit the bettong’s ground‑dwelling habits. Habitat loss and fragmentation from agricultural expansion, mining activities, and road construction reduce the availability of the fungal-rich soils essential for survival. Altered fire regimes, especially high‑frequency burns, destroy the mycorrhizal networks and seed banks that underpin their diet. Competition with introduced herbivores such as rabbits (Oryctolagus cuniculus) further depletes vegetation cover and food resources. Conservation actions include targeted predator‑control programs, fire‑management plans that preserve mature shrubland, and the establishment of protected reserves on the Nullarbor Plain. Ongoing population monitoring and captive‑breeding initiatives aim to bolster genetic diversity and provide a safety net against extinction.

• One of the smallest diprotodont marsupials, weighing less than a kilogram.
• Relies on underground fungi for up to 70 % of its diet, making it a key disperser of fungal spores.
• Has a pouch that opens forward, unlike many other marsupials where it opens backward.
• Can leap up to 1.5 m in a single bound to escape predators.
• Populations have rebounded locally after intensive fox‑baiting programs.