Bridled nailtail wallaby
Common name: bridled nailtail wallaby, flashjack, merrin, waistcoat wallaby
Scientific name: Onychogalea fraenata
The bridled nailtail wallaby is a small wallaby with the adult weight range for males 5-8 kg and females 2-6 kg. It is grey to light tan in colour with distinct white lines forming a 'bridle' from the back of the neck to behind the forelimbs and along the sides of the face. It also has a black stripe down the length of the back. The early naturalist, John Gould, first described the species in 1840 as “…one of the most graceful objects that can be conceived”.
There are three species of wallaby that have the characteristic 'nail-tail', a small horny nail-like spur about 3-6 mm long at the tip of the tail: the bridled nailtail wallaby, crescent nailtail wallaby (believed to be extinct), and northern nailtail wallaby (common in northern Australia). It is unknown whether the 'nail-tail' spur serves a function. One theory is that it may aid their speed when the spur hits the ground and acts as a point on which the wallaby pivots during sharp turns.
Habitat and distribution
The bridled nailtail wallaby lives in dense acacia shrubland and open grassy woodland but prefers transitional vegetation between these areas. It was one of many species of kangaroos and wallabies hunted by many Aboriginal groups. At the time of European settlement, the bridled nailtail wallaby was a common species with a distribution reaching from the west of the Great Dividing Range, north to Charters Towers in Queensland, south to north-western Victoria, and possibly extending west to eastern South Australia. It now survives in a small percentage of the area it once inhabited.
For over 30 years the species was believed to be extinct as there had been no confirmed sightings since 1937. Then, in 1973 the species was ‘re-discovered’ by a fencing contractor who, after reading an article about Australia's extinct species in a magazine, reported that there was a population of bridled nailtail wallabies on a property in central Queensland near the town of Dingo. This was confirmed by Queensland Government researchers and this property and an adjoining property were eventually purchased and became Taunton National Park (Scientific). The current population estimate for Taunton National Park (Scientific), including neighbouring properties, is approximately 1,500 wallabies.
Life history and behaviour
Bridled nailtail wallabies are usually solitary animals, but sometimes form small aggregations (4-5 animals) when feeding or when females have young. The main defence strategy of the bridled nailtail wallaby is to hide rather than flee, which is uncommon in macropods. They are inactive during the day with most of their movement related to maintaining their position in the shade of bushes. Adults often rest and shelter in hollow logs or under young brigalow trees.
Bridled nailtail wallabies can breed all year round and potentially have three young per year. The gestation period is around 24 days and young stay in the pouch for 119-126 days. Immediately after the young emerge from the pouch the females hide their young in low, dense vegetation during daytime resting periods. They mature at a young age (females at 136 days and males at 270 days). However, it may take up to 18 months before a male is large and strong enough to successfully mate.
The preferred diet of the bridled nailtail wallaby is largely non-woody broad-leafed plants, chenopods (succulents including pigweed), flowering plants and grasses. Potential competitors for this food include the black-striped wallaby Macropus dorsalis, domestic stock and rabbits.
Threats that have contributed to the decline of the bridled nailtail wallaby in Queensland include:
- hunting of the bridled nailtail wallaby in the early 1900s for its fur and because it was considered a pest
- the contraction of its former range through the clearing of native vegetation as land was developed for agriculture and stock pasture
- habitat loss, modification and degradation through continued vegetation clearing, drought, changing fire regimes and introduction of weeds such as buffel grass
- predation by introduced predators such as foxes and feral cats, and to a lesser extent wild dogs
- competition with introduced stock (mainly sheep) and rabbits. Sheep predominantly browse on forbs in grassy areas, like the bridled nailtail wallaby.
A national recovery plan for the species was developed in 1991 and had three iterations until the last five-year plan was written in 2005 (Lundie-Jenkins & Lowry, 2005). A Conservation Advice was completed by the Commonwealth’s Threatened Species Committee in 2016, outlining conservation and management priorities for the species including:
- predator control at all sites of unfenced subpopulations and biosecurity measures at fenced subpopulations
- preventing habitat loss, disturbance and modifications
- implementing appropriate fire management regimes to protect key refugia habitat
- translocating individuals to supplement small existing subpopulations and to suitable sites within the former range to establish new subpopulations
- engaging organisations undertaking conservation actions for the species and local communities to promotes habitat conservation across land tenures
- monitoring the changes in subpopulation trends and the abundance of foxes, cats, wild dogs and dingoes at unfenced subpopulations
- monitoring the progress of conservation actions, including the effectiveness of management actions, and adapt them if necessary, to contribute to species recovery.
Existing conservation measures
Predator control: Department staff and the Queensland Conservation and Wildlife Management branch of the Sporting Shooters’ Association of Australia undertake predator control activities at Taunton National Park (Scientific) and Avocet Nature Refuge. The primary target species are feral cats and foxes , but wild dogs and rabbits are also controlled. By controlling predators, landholders on properties surrounding Taunton and Avocet provide a protective buffer around the bridled nailtail wallaby populations.
Re-introductions: New populations of the bridled nailtail wallaby have been established in habitats it once occupied to aid recovery of the species in the wild. During 2001 – 2005, bridled nailtail wallabies were released into Avocet Nature Refuge, part of a large private property south of Emerald, and is now home to a second population of approximately 100 wallabies. In 2014, a ‘nursery’ enclosure was funded by Wild Mob and built on Avocet Nature Refuge to reduce the high mortality rate of young bridled nailtail wallabies from predation by feral cats. Independent wallabies weighing less than 3 kg and females with pouch young caught in the wild are released into this 9.2 hectare predator-proof enclosure. Once adult females within the nursery are not supporting young, and juveniles have matured into adults weighing more than 3 kg, they are released back into the wild at Avocet. Given the absence of effective feral cat control strategies, this head-starting program is a relatively cost-effective and successful conservation option.
A translocated population was established at Idalia National Park in 1996 however after a rapid decline from predation and drought the last remaining animals were captured and taken into captivity in 2015 and the species is not believed to have persisted in the area.
A recent collaboration between the New South Wales (NSW) and Queensland governments and the Australian Wildlife Conservancy (AWC) has established a population at a large fenced enclosure at Pilliga State Conservation Area in NSW. Bridled nailtail wallabies were translocated from both Taunton National Park (Scientific) and the AWC-managed Scotia Sanctuary in NSW to establish this population. A further fenced population is proposed for Mallee Cliffs National Park in NSW in 2020-21.
Captive populations: An educational display of captive bridled nailtail wallabies can be viewed by the public at David Fleay Wildlife Park, Burleigh Heads, Queensland.
What can you do to help this species
- Landholders in the areas where bridled nailtail wallabies have been known to occur should report sightings to their local departmental office.
- As has been done with Avocet Nature Refuge, perpetual conservation agreements can be used to conserve areas of remnant vegetation that provides habitat for bridled nailtail wallabies. Under such agreements, incentives and support are provided to landholders and access to the property can be negotiated.
- Volunteer with organisations, like Bush Heritage Australia, assisting on-ground activities to recover the species.
- Research can also help the bridled nailtail wallabies by discovering information that will improve their conservation management. Recent research projects include:
- the University of NSW found that ‘head-starting’ has decreased mortality of juvenile wallabies and increased the translocated Avocet population
- the department, Biosecurity Queensland (Department of Agriculture and Fisheries) and the University of Queensland showed that the survival of the juvenile wallabies increased following Eradicat baiting programs targeting feral cats
- dietary studies by the department, Wildlife Queensland and Central Queensland University found that despite expansion of buffel grass in recent decades, bridled nailtail wallabies do not favour this introduced grass. Rangers will continue to suppress buffel grass at Taunton.
Gordon, G and Lawrie, BC 1980. The rediscovery of the bridled nailtail wallaby (Onychogalea fraenata Gould) in Queensland. Australian Wildlife Research 7: 339-345.
Horsup, A and Evans, M 1993. Predation by feral cats, Felis catus, on an endangered marsupial, the bridled nailtail wallaby, Onychogalea fraenata. Australian Mammalogy 16(1): 85-86.
Johnson, PM 2003. Kangaroos of Queensland. Queensland Museum, Brisbane.
Lavery, HJ and Tierney, PJ 1985. 'Scarcity and extinction', in Lavery, HJ (ed.), The Kangaroo Keepers. University of Queensland Press, St Lucia.
Lundie-Jenkins, G and Lowry, J 2005. Recovery plan for the bridled nailtail wallaby (Onychogalea fraenata) 2005-2009. Report to the Department of Environment and Heritage (DEH), Canberra.
Threatened Species Scientific Committee (2016) Conservation Advice Onychogalea fraenata bridled nailtail wallaby. Canberra: Department of the Environment and Energy. Available from http://www.environment.gov.au/biodiversity/threatened/species/pubs/239-conservation-advice-16122016.pdf. In effect under the EPBC Act from 16-Dec-2016.