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
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.
Hypsiprymnodon moschatus ('high rump and musky odour')
Crater Lakes National Park, Queensland
The Crater Lakes National Park has two sections - Lake Barrine and Lake Eacham. Both Lakes are within the Wet Tropics World Heritage area. The Lakes are fringed by rainforest where the Musky Rat-Kangaroo and Red-legged Pademelon can be seen by day. At night, Lumholtz's Tree-kangaroo may be viewed along the various walking trails at each Lake. The Park does not have accommodation or camping but is near Cairns and other locations in the Atherton Tablelands of Queensland that have a full range of accommodation.
The Musky Rat-kangaroo inhabits tropical rainforest with a diverse overstorey of trees that supply its mainly frugivorous (fruit-eating) diet. The main vegetation type is a complex mesophyll vine forest in both tablelands and coastal areas. Habitat fragmentation through clearing for livestock grazing and agriculture and horticulture has severely reduced its habitat. In the tablelands fragmentation leads to local extinction and persistence in only very large fragments of intact forest.
The diet of the Musky Rat-kangaroo diverges from the other rat-kangaroos as they eat mainly fruit. These are supplied by a number of trees such as Figs (Ficus spp.), Quandongs (Silver Quandong - Elaeocarpus augustifolia), Walnuts (Boonjie Blush Walnut - Beilschmiedia volcanii, Hairy Walnut - Endiandra insignis), Lilly-pillies (Watergum - Syzygium gustavioides), and vines like Austrobaileyana scandens). They also eat seeds with soft coats, roots and tubers, the fruiting bodies of hyopeous and epigeous fungi, and some invertebrates. Unlike other Rat-kangaroos, they forage mainly in the day.
The Musky Rat-kangaroo like most of the rat-kangaroos has a gestation period (19 d) shorter than the oestrous cycle (26 d) but has no post-partum oestrus (i.e. mating taking place very soon after the current pouch young vacates the pouch permanently) and no embryonic diapause. The do not breed continuously but rather males' testes enlarge dramatically in October in advance of the Wet season and shrink (recrudescence) after April when the Dry season commences. Females carry pouch young from March until October with a 5-6 month pouch life so that permanent pouch exit is in the Wet season. They can raise 1-3 young in a single litter. Other Rat-kangaroos can have two young in the pouch from separate oestrous events but rarely raise the smaller of the two to pouch exit.
With the increase in testes size and testosterone production, males become more aggressive in the breeding season. They chase other males off but the competition may be resource-based (over fruit) as much as for mates. Fighting is usually a strike with the forepaw and thus relatively less damaging than the other Rat-kangaroos.
Musky Rat-kangaroos live at relatively very high densities of 140 - 450 per km2 compared to other Rat-kangaroos. Home ranges are thus very small with a mean of 2.1 ha for males and 1.4 ha for females. Both the foraging ranges of individuals and the location of nest sites overlap. This packs more individuals into the habitat allowing high densities. Musky Rat-kangaroos may form small aggregations of 2-3 individuals foraging on fallen fruit.
Claridge AW, Seebeck JH, Rose R (2007) 'Bettongs, Potoroos and the Musky Rat-kangaroo.' (CSIRO Publishing: Melbourne).
Dennis AJ, Marsh H (1997) Seasonal reproduction in musky rat-kangaroos, Hypsiprymnodon moschatus: A response to changes in resource availability. Wildlife Research 24, 561-578.
Dennis AJ (2002) The diet of the musky rat-kangaroo, Hypsiprymnodon moschatus, a rainforest specialist. Wildlife Research 29, 209-219.
Lloyd S (2001) Oestrous cycle and gestation length in the musky rat-kangaroo, Hypsiprymnodon moschatus (Potoroidae: Marsupialia). Australian Journal Of Zoology 49, 37-44.