Burrowing Bettongs are one of Australia's most endangered animals.
They are thriving at Arid Recovery, for better and for worse...
Range and abundance
The Burrowing Bettong (Bettongia lesueur lesueur), also known as the Boodie, was once one of the most widespread of all Australian mammals. It was found across arid and semi-arid zones in Western Australia, South Australia, western New South Wales and Victoria. In 1863 the Burrowing Bettong had disappeared from Victoria and by 1942 the last specimen was collected on mainland Australia in Western Australia’s southern wheatbelt district. However, there are reports by Aboriginal people that they may have survived until the late 1950s in the desert regions of South Australia.
The Burrowing Bettong is now only found naturally on four islands off the coast of Western Australia. It has been successfully re-introduced to predator-proof enclosures in Western Australia, South Australia and New South Wales.
The Burrowing bettong belongs to the Macropod family, which includes kangaroos and wallabies. They have short, round ears and a small nose. Their fur is a yellow-grey colour on their back and light grey on their belly. They have a fat, light grey coloured tail which is dark at the base and often has a paler tip. On average, Burrowing Bettongs weigh around 1300 g and are 700 mm from head to tail tip. A bettong’s hind legs are similar to those of a kangaroo, enabling it to jump on its hind legs.
Burrowing Bettongs are extremely vocal and communicate using a series of hisses, grunts and squeals, some of which sound uncommonly like a fart. Males can be extremely aggressive towards each other.
Burrowing Bettong warren with multiple entrances
The Burrowing Bettong is strictly nocturnal and during the day shelters underground within a burrow, the only Macropod to do so. The burrows are constructed in deep loam or sandy areas. Their burrows are often complex and can form warrens, which have multiple entrances and inter-connecting passages. The floor of the warren is lined with vegetation to create nests for sleeping. Many individuals may live within the warren. Bettongs have a matriarchal society, with one dominant female, her daughters and subordinate males occupying the warren. A complex warren found on Barrow Island had 120 entrances and about 60 Bettongs living in it. The maximum number of entrances recorded in warrens at Arid Recovery is 12.
The Burrowing Bettong is mainly a browsing animal and at Arid Recovery, it eats a wide variety of foods, including leaves, seeds, roots and occasionally insects. They do not need to drink, obtaining all their water from their food. During dry times, Burrowing Bettongs will eat the bark and roots of plants to obtain moisture.
Bettongs love to eat native plum (Santalum lanceolatum). They have browsed the leaves from this tree up to the height they can reach, leaving a clear line.
Burrowing Bettongs have a single baby, which lives in the mother’s pouch for 115 days. They can breed all year round and up to 3 young may be raised within one year. Breeding is only paused if it has been a particularly dry period.
The rapid disappearance of Burrowing Bettongs from the mainland appears to be largely due to predation by foxes and feral cats. Other factors in their decline include competition with rabbits for food and shelter, hunting and poisoning by early farmers, and the removal of the Bettong’s habitat for pasture and crops. Burrowing Bettongs are listed as vulnerable on the national list of Threatened Species.
What is Arid Recovery doing?
In 1999 and 2000 Arid Recovery introduced 29 Burrowing Bettongs from Bernier Island and Heirisson Prong in Western Australia into the reserve. Without predation from feral cats and foxes or competition from rabbits, the population of Burrowing Bettongs within the reserve has exploded and the population is currently estimated to be more than 8000 individuals and genetically diverse.
Bettongs are an extremely easy animal to trap and their inquisitive nature makes them an easy target for feral cats and foxes. Currently this makes them almost impossible to establish populations of Burrowing Bettongs beyond the fence.
The University of New South Wales in collaboration with Arid Recovery has developed a project ‘Tackling Prey-Naivety’ to try and improve the anti-predator responses of Burrowing Bettongs to cats and foxes. The project has seen positive results already, with Burrowing Bettongs being able to survive and breed whilst living alongside low densities of cats in one of Arid Recovery’s experimental enclosures. Even more encouraging, bettongs have shown signs of changing their behaviour to be more wary of predators.
The Over-abundance Problem
Bettongs stripped the bark from the base of this hopbush (Dodonea viscosa). Photo by Cat Lynch
The rapid population boom of Burrowing Bettongs inside the reserve has resulted in over-browsing of vegetation and has possibly had implications for the survival of other species within the reserve such as the Greater Stick-nest Rat (Leporillus conditor).
Arid Recovery has implemented a system of one-way gates which enables Burrowing Bettongs to naturally disperse outside the reserve. The gates have been specially designed to limit the use by other species within the reserve. The one-way gates are accompanied by intensive feral predator control to give the Burrowing Bettongs the best chance of surviving. Camera traps have been placed at each gate and are monitored closely by the Arid Recovery team to determine how many bettongs are leaving the reserve and whether other animals are using the gates as well.
Written by Rachael Loneragan (March 2017)