Bridled nailtail wallaby
Bridled nailtail wallaby. Photo:EHP
Common name: bridled nailtail wallaby, flashjack, merrin, waistcoat wallaby
Scientific name: Onychogalea fraenata
Conservation status: This species is listed as Endangered in Queensland (Nature Conservation Act 1992) and nationally (Environment Protection and Biodiversity Conservation Act 1999). It is ranked as a critical priority under the Department of Environment and Heritage Protection (EHP) Back on Track species prioritisation framework.
The bridled nailtail wallaby is a small wallaby with males weighing an average of 5-6 kg and females 4-5 kg. It is grey to light tan in colour with a distinct white line forming a 'bridle' from the back of the neck to behind the forelimbs. Its other distinctive markings are the white stripes along the sides of the face, and a black stripe down the length of the back.
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, but 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 semi-arid areas where dense acacia shrubland and grassy woodland meet. At the time of European settlement it 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. The bridled nailtail wallaby now survives in a small percentage of the area it once inhabited.
For over 30 years they were believed to be extinct as there had been no confirmed sightings of individuals 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 researchers from the Queensland Parks and Wildlife Service and the property eventually became Taunton National Park (Scientific). Current population estimates for Taunton National Park (Scientific), including neighbouring properties, are approximately 200 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 fairly 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 are able to breed all year round and can potentially have three young per year. The gestation period is around 24 days and young stay in the pouch for about 120 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. Two potential competitors for this food include the black-striped wallaby Macropus dorsalis and domestic stock.
Threats that have contributed to the decline of the bridled nailtail wallaby, the contraction of its former range (historical distribution) and threats that impact on existing wild (Taunton National Park) and translocated populations (Idalia National Park, Avocet Nature Refuge) include:
- Hunting of the bridled nailtail wallaby in the early 1900s for its fur and because it was considered a pest
- 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 less extent wild dogs
- Competition with introduced stock (mainly sheep) and rabbits. It has been found that sheep favor grassy areas similar to the bridled nailtail wallaby.
The Recovery Plan for the bridled nailtail wallaby recommends the following actions:
- Preserve preferred habitat and increase the existing wild populations
- Conserve the only known remnant population at Taunton National Park
- Protect and enhance the two reintroduced populations at Idalia National Park and Avocet Nature Refuge
- Determine suitable sites for future reintroductions
- Continue feral predator control programs where appropriate and reduce the threat of fire and buffel grass on existing wild populations
- Support the current Captive Breeding Agreement.
Existing conservation measures
Predator control: The Queensland Hunting and Conservation division (H&C) of the Sporting Shooters’ Association of Australia (SSAA) undertake predator control activities at Taunton National Park and Avocet Nature Refuge. The primary target species are foxes and feral cats although dingoes and rabbits are taken as well depending on numbers present.
Re-introductions: New populations of the bridled nailtail wallaby have been re-introduced to habitats it once occupied to aid recovery of the species in the wild. In 1994 bridled nailtail wallabies were introduced to Idalia National Park and currently the population is estimated to be approximately 100 wallabies.
During 2001 – 2005, bridled nailtail wallabies were released into part of Avocet, a large private property south of Emerald. In 2003, this part of the property was gazetted as a Nature Refuge – Avocet Nature Refuge - and is now home to a third population of approximately 100 wallabies.
Captive breeding: Captive populations of bridled nailtail wallabies are maintained by Australian Animals Care & Education Inc. (AACE) in Queensland, and Scotia Sanctuary (owned and managed by the Australian Wildlife Conservancy) in New South Wales, for the purposes of research and education, and for reintroduction to the wild.
In August 2008, EHP entered into a Captive Breeding Agreement with AACE to aid recovery of this species. The purpose of the captive breeding undertaken by AACE is to breed bridled nailtail wallabies for reintroductions into the wild, and supplement the existing populations (in Queensland and NSW) with genetically diverse individuals. Through this program, AACE have been able to release bridled nailtail wallabies at Idalia National Park and Avocet Nature Refuge (the two reintroduction sites in Queensland).
A Masters study finished in 2008 by Lisa Kingsley at the University of Queensland evaluated the success of the reintroduced population of bridled nailtail wallaby at Avocet Nature Refuge. Although there was only a slight increase in the population from 2005 to 2008, the study found that the population was doing well as the wallabies had good body condition and a lower reproductive failure rate.
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 EHP 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.
- Research can also help the bridled nailtail wallabies by discovering information that will improve their conservation management. Current research projects undertaken by the University of Queensland are investigating the effects of food quality on different populations, the impacts of introduced predators, and habitat restoration.
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.