General information

Kangaroos are marsupials and belong to the Family Macropodidae (i.e. big feet) that is grouped with the Potoroidae (potoroos, bettongs, rat-kangaroos) and Hypsiprymnodontidae (musky rat-kangaroo) in the Super-Family, Macropodoidea. This comprises around 50 species in Australia and a dozen or more in New Guinea.  Some of the smaller species, such as Yellow-footed Rock-Wallabies, Burrowing Bettongs, accompanied Pig-footed and Golden Bandicoots, Bilbies and possibly Hairy-nosed Wombats into extinction with the advent of pastoralism. However, the largest species remain in much of their original range with the grey kangaroos expanding inland as grazing habitat increased and coastal habitat was lost in clearance for agriculture. The defining feature of the kangaroo family is that they are the largest vertebrates to hop (both currently and from what we know from palaeontology).

The Bettongs, Potoroos and Musky Rat-Kangaroo are collectively known as the Rat-kangaroos. In fact, they form two families, the Potoroidae, which includes all the potoroos and bettongs, and, the Hypsiprimnodontidae, whose sole living representative is the Musky Rat-kangaroo. They are observationally distinguished from the kangaroos and wallabies by their diminutive body size but the largest species, the Rufous Bettong, eclipses the smallest Rock-wallabies, the Monjon and Narbelek. In general, they retain more 'primitive' ancestral characteristics with a partly prehensile tail to entrap grasses and sticks for nesting and a simpler stomach (and consequently richer diet). The forelimbs and hindlimbs are more similar in size than the gross differences in the kangaroos and wallabies, and so bounding as well as hopping is a mode of progress. Perhaps possum-kangaroo is more accurate but the first European observers were more familiar with rats than possums.

If you find an intact skull on your exploration of rat-kangaroo habitat then the dentition is clearly distinguishable from the kangaroos. They are more buck-toothed with the second and third incisors smaller than the first and more lateral in the upper jaw. The upper canines are well-developed whereas they are lost in the Macropdodidae. The premolar is large and blade-like and the molars are retained rather than lost anteriorly through wear and progress along the tooth row.

The rat-kangaroos have fared very poorly with the advent of agriculture and pastoralism compounded by the introduction of competitors (European rabbits and hares) and predators (Red foxes and domestic cats). The Potoroids generally have much reduced ranges relative to the first settlement of Australia by Europeans and two of the 10 species are extinct. The most dramatic of the declines is the Boodie (Burrowing Bettong) which was widespread across the rangelands of Australia and ended up marooned on a few offshore islands in Western Australia. Reintroductions are in progress and this species is on the first hops to making a comeback on the mainland. Like the Potoroids, the Musky Rat-kangaroo has lost much of its habitat in the highly prized real-estate of the tropics.

Species

Woylie (Brush-tailed Bettong)

Bettongia penicillata ogilbyi ('brush bettong')

Best place to see

Dryandra Woodland, Western Australia

Dryandra Woodland is 164 km southeast of Perth and is a haven for threatened mammal species through circumstance and design via the Barna Mia animal sanctuary. Here you can find free-ranging Woylies (Brush-tailed Bettongs) along with Western Brush Wallabies , Western Grey Kangaroos and Tammar Wallabies. The Sanctuary includes Banded Hare-wallabies, Rufous Hare-wallabies and Boodies (Burrowing Bettongs) for breeding and release in extensive re-introduction programs in Western Australia. The Woodland is best known for another marsupial, the Numbat.

Accommodation is available in cabins and there is a well-serviced camping ground.

The Paruna Sanctuary in the Avon Valley near Perth is also an excellent place to see Woylies. This is one of a number of sanctuaries run by the Australian Wildlife Conservancy that have re-introduced threatened macropods into parts of their former range. The Woylie has been a particularly successful member of these re-introductions. The Paruna Sanctuary has visitor facilities but access is by prior arrangement. Woylies have also been introduced into Australian Wildlife Conservancy properties at Scotia in New South Wales and Yookamura in South Australia. These sanctuaries also have Boodies and Mala but access is only through volunteering programs.

Woylie introductions have been made to the Arid Recovery reserve at Roxby Downs in South Australia where tours/stays and options for volunteering are provided.

Identification

Woylies average 1.3 kg and reach a weight of 1.6 kg. The general back colour of the Woylie is a grizzled brown-grey and there are long hairs which have a blue-grey base and a short dark brown or black tip. The face is short and the base of the ears are hairy and have a rufous tinge. The nose is naked and dark brown. The colour of the underside is a pale yellow-grey. The legs are coloured much like the dorsal surface and the fore- and hind-feet are medium brown. The base of the long tail is similar in colour to the back but the terminal one to two thirds is dark brown to black above and is prominently crested (hence the name Brush-tailed Bettong). The underside the tail is pale grey brown and it is very rare in this species to see a white tail tip. As with the rest of the Bettongs, the claws are the three central claws of the fore-paws and very long slender and curved.

Habitat

Like the Boodie, the Woylie was once the most widespread in the rangelands of Western Australia, Northern Territory, South Australia, New South Wales and north-western Victoria. At the time of discovery there were three disjunct populations - a north-western, south-western and south-eastern - of which only the south-western remains with the sub-specific name of ogilbyi. From these founders, reintroductions have been made into fenced reserves in South Australia, NSW and Western Australia. Intensive fox control in the south-west has seen expansion of populations from their remnant distribution.

 

 The Woylie favours dry sclerophyll forest and woodlands with an overstorey of Jarrah (Eucalyptus marginata) and Wandoo (E. wandoo). The understorey is formed by low xeric scrub or tussock grasses. In the Francoise Peron National Park at Shark Bay in Western Australia and Scotia Sanctuary in western NSW, Woylies and Boodies co-exist through introduction and in the latter area use similar microhabitats favouring sites with 10-25% canopy cover relatively high ground cover and height.

Foraging behaviour

The diet of the Woylie is similar to Potoroos as includes a large diversity and proportion of hypogeous fungi in its diet particularly in summer and autumn in dry sclerophyll forest in WA.  Plant material such as roots and tubers, leaves and gum exudate are common in the spring-winter diet. Some animal matter, various invertebrates, is also eaten. As Woylies are reintroduced into various parts of their former range knowledge of the components of their diet has broadened. Fruit and seeds are consumed and amongst these the large fleshy seeds of the native sandalwood (Santalum spicatum) are an ecologically and commercially important component. With over-exploitation of sandalwood resources in India and other parts of Asia, Australian sandalwood has become an important and valuable part of the production of incense. Commercial cropping is now encouraged and clearly Woylies are and have been important in dispersal of this species through seed caching in the same way squirrels disperse acorns. Woylies no doubt also ate the fruit of the sandalwood's relative, the quandong (Santalum acuminatum), which is also in commercial production for the 'bush tucker' trade.

 

The foraging of Woylies, like the other bettongs and potoroos, alters soil structure and is likely to be beneficial to increasing the permeability of hard surfaces and the incorporation of humus into the soil. Thus the extinction of this species across almost all of its range at the time of European settlement has come at a considerable cost to the dispersal and viability of now commercially important trees and the adverse compaction of soils. Thus the various intensive and small-scale projects to bring the Woylie back into the rangelands should be applauded for their economic sense.

Reproductive behaviour

The Woylie like most of the rat-kangaroos has a gestation period just shorter than the oestrous cycle and thus has a post-partum oestrus with mating taking place very soon after the current pouch young vacates the pouch permanently. However, if a male is not present ovulation does not occur and the female will not enter oestrus until introduced to a may. Woylies show embryonic diapause and breed continuously regardless of season. Pouch life is around 3.5 months and thus they are able to produce more than one young per year. Males become sexually mature at around 13 months and females much earlier at 10 months. In captivity on a high quality diet, breeding may commence earlier and the maximal production of 3 young per year achieved but more usually two.

 

In spite of a number of captive breeding programs the reproductive behaviour of the Woylie is not well-described but likely to be typical of the other rat-kangaroos with ardent males repelled by similar-sized unreceptive females until such time as they reach oestrus. Nests are constructed and it is likely that male Woylies regularly visit the nests of females within their home range.

 

Social organisation

Woylies occupy relatively large home ranges with a range of 28-43 ha for males and 15-28 ha for females. Individuals of the same sex (especially males) defend a core nesting area of a few hectares with some overlap between male and female nesting areas and substantial overlap in foraging areas between the sexes. Multiple nests are found in the core area of a home range but usage has no definable pattern. For the most part, individuals lead a solitary existence but overlap sufficiently on foraging ranges for females to potentially have multiple male partners. Dispersal is male biased with young males rapidly recolonising areas where residents may have been killed in woodland fires.

 

Further readings

Claridge AW, Seebeck JH, Rose R (2007) 'Bettongs, Potoroos and the Musky Rat-kangaroo.' (CSIRO Publishing: Melbourne)

Garkaklis MJ, Bradley JS, Wooller RD (1998) The effects of Woylie (Bettongia penicillata) foraging on soil water repellency and water infiltration in heavy textured soils in southwestern Australia. Australian Journal Of Ecology 23, 492-496.

Murphy MT, Garkaklis MJ, Hardy GESJ (2005) Seed caching by woylies Bettongia penicillata can increase sandalwood Santalum spicatum regeneration in Western Australia. Austral Ecology 30, 747-755.

Smith MJ (1994) Male-induced oestrus and ovulation in female brush-tailed bettongs (Bettongia penicillata) suckling a young in the pouch. Reproduction Fertility And Development 6, 445-449.