Greater Bilby
Revitalising the desert through their ecological impact
The diggings of greater bilbies improve soil quality, water retention, and create homes for various species. Restoring bilby populations can contribute to the health of arid landscapes by enhancing soil structure and supporting biodiversity
Beginning with just nine bilbies from a breeding program at Monarto in 2000, and later adding 28 more from Thistle Island in South Australia in 2005, the greater biliby population at Arid Revovery has expanded to between 800 to 1500 individuals.
WHAT HAS ARID RECOVERY LEARNT?
Greater bilbies are ecosystem engineers
Bilby diggings restore the soil and regrowth of the vegetation. By creating deep holes in the sand, they enable plant material to fall and decompose. Each bilby creates numerous compost pits every night. These become high in carbon and nitrogen – an important nutrient for the growth of plants and the germination of seeds.
Greater bilbies can be taught: tackling-prey naivety
Bilbies are extremely susceptible to cat and fox predation outside the protective reserve. In 2005, Arid Recovery initiated a training program to teach bilbies to recognise cats as predators, with the hope of improving their chances of survival beyond the reserve's borders. Researchers exposed bilbies to taxidermy cats and cat urine during the training process. Trained bilbies exhibited behaviours such as moving further away, using more burrows, and changing burrows more frequently compared to untrained bilbies. However, when bilbies were introduced to an area with live cats, there was no discernible difference in survival rates between the trained and untrained bilbies.
The training of bilbies using taxidermy cats and cat urine proved ineffective in improving the survival rates of bilbies in the presence of real feral cats. In response, a new project named "Tackling Prey Naivety" was initiated by UNSW, the University of California, and Arid Recovery. In 2016, bilbies were exposed to a low density of feral cats within the Red Lake Expansion area for two years. Our findings revealed that bilbies were capable of coexisting with a low density of cats and showed a preference for spending more time in covered habitats compared to bilbies in the cat-free parts of the reserve. Subsequently, when researchers increased the cat density and introduced both exposed and unexposed bilbies, the exposed bilbies demonstrated a higher likelihood of survival.
WHAT IS ARID RECOVERY DOING?
How do heatwaves affect bilbies?
Researchers from the University of New South Wales, in collaboration with Arid Recovery, are studying the effects of extreme heat events on native and invasive mammals. As climate changes increases the longevity and severity of heatwaves, it is essential we understand how animals will fare under a warming future climate. By equipping bilbies with a combination of radio and GPS transmitters, data loggers, and accelerometers, they aim to understand how bilbies adjust their foraging and sheltering behaviors during heatwaves. The project employs thermal cameras mounted on drones to map microclimates within the habitats of the tracked animals.
SPECIES PROFILE
Range and abundance: The greater bilby was once found on 70% of Australia’s mainland, but now occupies just 20% of its former range. Scattered populations remain in the Tanami, Gibson and Great Sandy Deserts, as well as the Pilbara and Kimberley regions, and the Mitchell grasslands in Southwest Queensland. They have also been reintroduced to a few protected sites across Australia.
Shelter: Bilbies construct spiral-shaped burrows which can be up to three meters long and two meters deep. The entrance to a bilby burrow is often under a small shrub, and at Arid Recovery is usually left open. At other sites, bilbies often backfill their burrow entrance, possibly to protect it from predators or to regulate temperatures. Bilbies frequently dig new burrows and visit up to ten per night.
Feeding: Bilbies have an excellent sense of smell and hearing, which they use to find food. They can detect food a metre underground and use their long sticky tongue to lick up seeds and insects. This causes bilbies to ingest a lot of sand during foraging – meaning 20–90% of their faeces may be composed of sand!
Breeding: Bilbies breed year-round and have a gestation period of 12 – 14 days. The joeys spend the first 80 days of their lives in from their mother’s pouch. Two weeks after emerging the pouch, young bilbies become independent. The pouch is backward opening, so when the mother bilby digs, the pouch does not fill with sand.
Threats: The rapid decline in the bilby’s range is largely due to feral cats and foxes. Grazing by rabbits and livestock, the fragmentation of habitat by land clearing, and changed fire regimes have also contributed. Now classified nationally as vulnerable, the fate of the greater bilby is hanging in the balance. A relative of the greater bilby, the lesser bilby is now completely extinct. Just 100 years ago, it was considered to be common.