Wildlife Matters

Australia’s ecosystem engineer: The Greater Bilby

20 Nov. 2018
© Wayne Lawler/AWC

By Felicity L’Hotellier, Senior Field Ecologist

The Greater Bilby (Macrotis lagotis) once occurred across 70 per cent of the mainland of Australia; it is now found only within some 20 per cent of its former range, and continues to disappear from the Australian landscape. Remaining populations are mostly limited to the Tanami Desert (Northern Territory), western deserts, Pilbara and Kimberley regions (Western Australia) and the Diamantina region (Queensland). It is estimated that there are less than 10,000 individuals remaining. Its closest relative, the Lesser Bilby (Macrotis leucura), has been presumed extinct since the 1960s. The key cause of this decline is a sad and repeated story when it comes to Australian wildlife, with predation by feral cats and foxes ranking in top place.

AWC now protects about 10 per cent of the global Bilby population at Scotia, Yookamurra and Mt Gibson Wildlife Sanctuaries, and is working with the Queensland Government to protect populations at Astrebla and Diamantina National Parks. Before the end of 2018, Bilbies from Scotia will be taken to the feral predator-free area in the Pilliga.

While traditionally known by many names, the common name ‘Bilby’ was derived from the New South Wales Ularoi/Yuwaalayaay language name, ‘Bilba’. The Bilby continues to hold deep significance to many Indigenous Australians. It is a totem animal and plays a part of the Dreamtime stories. Their song lines and stories reach out across the country. In some areas Bilbies were also hunted as food and their tails used as decoration.

Often compared to the introduced rabbit, the Bilby is a unique and charismatic Australian native, sparking awe and curiosity in the observer. Long-pointed ears, held erect; an elongated snout with a keen sense of smell; a bi-coloured tail which flicks from side to side as it runs; and claws, perfectly designed for ploughing soil. Soft, downy fur across the body transforms into a coarse, crested ‘Mohawk’ along the tail. Active at night, the Bilby spends its days sheltering in a long, often spiral shaped burrow that it skilfully constructs.

It has a wide and varied diet and the dentition to match. Invertebrates, seeds, fruit, fungi and small vertebrates make up most of its diet. A flexible palette allows the Bilby to thrive in tough conditions.

One of over 150 marsupials in Australia, the Bilby gives birth to small, under-developed young, which make their way into their mothers’ pouches to continue growing. The young (often twins) remain in the pouch for almost three months, after which they are deposited in a burrow and suckled by the mother until they are ready to make their way into the world. Given sufficient resources, breeding is continuous. The pouch is backward facing, and for good reason – the Bilby is a compulsive digger.

Through its digging efforts, a single Bilby, whose weight can reach up to 2.5 kilograms for males and 1.1 kilograms for females, can turn over several tonnes of soil per annum. The pits that they create while digging for food provide a huge environmental benefit and the reason that Bilbies are often referred to as ‘ecosystem engineers’. Their digging helps water to infiltrate the soil profile, collect leaf litter and collect seeds. Through these efforts, fertile pockets are created providing the perfect germination conditions for plants. Their continual digging helps cycle organic material and nutrients back into the ground. Our Bilbies are skilled tillers, helping to maintain the health of our soils.

The Bilby is part of our unique Australian fauna. It serves an important role in the ongoing health and function of our ecosystems, and holds deep cultural significance. It is important that we see Bilbies thrive once again across the Australian landscape.

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