A study of bilby behaviour in temperate climates could open the door for the Australian marsupial to be reintroduced to areas it once roamed.
Greater bilbies (Macrotis lagotis) are mostly associated with inland arid environments, but they ranged throughout temperate parts of Australia’s south more than a century ago.
And while bilbies have been pushed to the brink of extinction by predation by cats and foxes and competition for resources with rabbits, carefully managed habitats could provide an opportunity for the endangered marsupial to return to its former region.
“If bilbies are to be restored in the temperate zone where they once thrived, we need to know much more about where they like to go and what they need there,” says UNSW ecologist Kate Cornelsen.
She led a study, published in the journal Animal Behaviour, investigating the movements of 20 bilbies in a sanctuary at Taronga Western Plains Zoo in Dubbo, New South Wales.
Movements were monitored using small GPS trackers fitted to each bilby’s tail. As nocturnal mammals, bilby behaviour has been difficult for researchers to observe, but hourly location data fed back to Cornelsen’s team has shed light on key patterns in bilby movement and resource use.
It’s potentially critical for attempts to help bring bilbies back to southwestern and southeastern Australia.
Soils and sexes
Females are the sole caregivers of baby bilbies and must make safe burrows to bundle up their offspring while also finding food. These competing priorities appear to result in female bilbies exercising discretion when it comes to the terrain they choose to range.
Their male counterparts, on the other hand, seem happy to go anywhere to grab a feed.
Rather than the sandy soils associated with their current range in Australia’s northwest, bilbies in the Taronga sanctuary would burrow in both sand and silty, water-adjacent terrain.
“What’s interesting about this is that it shows the diversity of soil types bilbies can exploit – they’re not just limited to sandy soils good for burrowing,” says Cornelsen.
While water in the arid regions of their current range is scarce, those in temperate climates may have the choice of rivers and streams to hunt for a meal. Bilbies are omnivores that obtain substantial nutritional benefit from insects.
But Cornelsen notes moving towards water sources to retrieve a meal of bugs also carries a risk of venturing into flood-prone areas, depending on the habitat.
And water sources aren’t essential for bilbies either.
“Food is probably less patchy and more predictable in this study area compared to the desert where they’ve been studied before,” Cornelsen says.
“Areas further from water probably still provide sufficient food for bilbies, and because bilbies get all of the water they need from their food, being further from water might help them avoid competition with other species that do need to drink.
“For future bilby reintroductions, we will now have greater confidence in the resources required by the species within temperate regions.”
