The taxonomy of Wallabia bicolor is still controversial. Because it can hybridize with the agile wallaby, Macropus agilis, many believe that it should be placed in the genus Macropus. However, because of its unique dentition, sexual dimorphism in chromosome number, and reproductive behavior, it is currently classified as the last living member of the genus Wallabia.
Perception Channels: tactile ; chemical
A decrease in the abundance of swamp wallabies has occured due to habitat destruction and, to a lesser degree, killing by farmers. However, Wallabia bicolor is still common and these issues are not currently considered threats to its survival.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
Because Wallabia bicolor are browsers, they sometimes damage agricultural crops. As a result, they are often shot by farmers who view them as pests.
The skins of Wallabia bicolor are often sold. Around 1500 skins are marketed each year in Queensland.
Swamp wallabies are strictly herbivorous. Their diet consists of soft plants such as buds, ferns, leaves, shrubs, and grasses. They have been known to eat bark, shoots from needle-leaf trees, and plants that can be poisonous to domesticated animals. Wallabia bicolor are browsers and use their reduced forelimbs to manipulate their food.
The swamp wallaby can be found on the eastern coast of Australia from southeastern South Australia, Victoria, eastern Queensland, and eastern New South Wales.
Biogeographic Regions: australian (Native )
Swamp wallabies generally live in, but are not restricted to, dense forests, woodlands, and swampy areas. They are known to venture into more open areas, but only if there are nearby areas of thick brush.
Terrestrial Biomes: forest
Average lifespan
Status: wild: 12.0 years.
Average lifespan
Status: wild: 15.0 years.
Average lifespan
Status: captivity: 12.4 years.
The swamp wallaby is a diprotodont marsupial with a bilophodont occlusal pattern. Females have pouches that open anteriorly and contain four mammae. The forelimbs, which are significantly smaller than the hindlimbs, contain five digits and are used for eating and slower movements. The hallux is absent in the hindlimbs which are syndactylous and elongated for use in rapid bipedal motion. The fourth toe is the longest and the most specialized digit of the hindfoot. This, along with the loss of the hallux, has adapted this species for hopping. Wallabia bicolor is, on average, 70 cm tall with males weighing 12.3-20.5 kg and females weighing 10.3-15.4 kg. Body and tail length vary according to sex; males are 72.3-84.7 cm long with a tails of 69-86.2 cm and females are 66.5-75 cm in length with tails ranging from 64 to 72.8 cm. The swamp wallaby has long, coarse fur that is generally dark brown in color with darker or black limbs and tails. Many also have a light yellowish cheek stripe that begins at the lip and continues towards the upper ear.
Range mass: 10 to 20 kg.
Average mass: 15.4 kg.
Other Physical Features: endothermic ; bilateral symmetry
Swamp wallabies, both male and female, attain sexual maturity at an age of 15 months and may live up to 15 years in the wild. Females are polyestrous and are able to breed all year long. They usually give birth to one young per cycle although twins have been reported. Following its birth, the young, normally weighing less than 1g, will spend the next 8-9 months in its mother's pouch. The gestation period is 33-38 days long while the estrous cycle is on average 34 days in length. This species is unique in that it is the only marsupial whose gestation period is longer than their estrous cycle. This means that females can mate during the last few days of their pregnancy allowing them continuous breeding and birthing approximately every 8 months. After this mating, a near term fetus is growing in one uterus while the new embryo is developing in a second. The suckling of the newborn temporarily halts the development of the second embryo which remains dormant until the first young is ready to leave the pouch. At this time, the second embryo resumes development and is born 33-38 days, the length of one gestation period, later.
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual
Average birth mass: 0.61 g.
Average gestation period: 36 days.
Average number of offspring: 1.
Average age at sexual or reproductive maturity (male)
Sex: male: 426 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 426 days.
The swamp wallaby (Wallabia bicolor) is a small macropod marsupial of eastern Australia.[3] This wallaby is also commonly known as the black wallaby, with other names including black-tailed wallaby, fern wallaby, black pademelon, stinker (in Queensland), and black stinker (in New South Wales) on account of its characteristic swampy odour.
The swamp wallaby is the only living member of the genus Wallabia.[4]
Historic names for the swamp wallaby include Aroe kangaroo and Macropus ualabatus, as well as banggarai in the Dharawal language.[5]
The swamp wallaby is found from the northernmost areas of Cape York Peninsula in Queensland, down the entire east coast and around to southwestern Victoria. It was formerly found throughout southeastern South Australia, but is now rare or absent from that region.[4]
It inhabits thick undergrowth in forests and woodlands, or shelters during the day in thick grass or ferns, emerging at night to feed. Brigalow scrub in Queensland is a particularly favoured habitat.[4]
The species name bicolor comes from the distinct colouring variation, with the typical grey coat of the macropods varied with a dark brown to black region on the back, and light yellow to rufous orange on the chest. A light coloured cheek stripe is usually present, and extremities of the body generally show a darker colouring, except for the tip of the tail, which is often white.[3]
The gait differs from other wallabies, with the swamp wallaby carrying its head low and its tail out straight.[4]
The average length is 76 cm (30 in) for males, and 70 cm (28 in) for females (excluding the tail). The tail in both sexes is approximately equal in length to the rest of the body. Average weight for males is 17 kg (37 lb), females averaging 13 kg (29 lb).[4]
The swamp wallaby has seven carpal bones in the wrist (humans have eight).[6]
The swamp wallaby becomes reproductively fertile between 15 and 18 months of age, and can breed throughout the year. Gestation is from 33 to 38 days, leading to a single young. The young is carried in the pouch for 8 to 9 months, but will continue to suckle until about 15 months.
The swamp wallaby exhibits an unusual form of embryonic diapause, differing from other marsupials in having its gestation period longer than its oestrous cycle.[4] This timing makes it possible for swamp wallaby females to overlap two pregnancies, gestating both an embryo and a fetus at the same time. The swamp wallaby ovulates, mates, conceives and forms a new embryo one to two days before the birth of their full-term fetus. Consequently, females are continuously pregnant throughout their reproductive life.[7]
The swamp wallaby is notable for having a distinct sex-chromosome system from most other Theria (the subclass that includes marsupials and placental mammals). Females are characterized by the XX pair typical of therians, but males have one X chromosome and two non-sequence homology Y chromosomes. This system is thought to arise from a series of chromosomal fusions over the last 6 million years.[8]
The swamp wallaby is typically a solitary animal, but often aggregates into groups when feeding.[3] It will eat a wide range of food plants, depending on availability, including shrubs, pasture, agricultural crops, and native and exotic vegetation. It appears to be able to tolerate a variety of plants poisonous to many other animals, including brackens, hemlock and lantana.[4]
The ideal diet appears to involve browsing on shrubs and bushes, rather than grazing on grasses. This is unusual in wallabies and other macropods, which typically prefer grazing. Tooth structure reflects this preference for browsing, with the shape of the molars differing from other wallabies. The fourth premolar is retained through life, and is shaped for cutting through coarse plant material.[4]
There is evidence that the swamp wallaby is an opportunist taking advantage of food sources when they become available, such as fungi, bark and algae. There is also one reported case of the consumption of carrion.[9]
Several physical and behavioral characteristics make the swamp wallaby different enough from other wallabies that it is placed apart in its own genus, Wallabia.[10][3] However, genetic evidence (e.g. Dodt et al, 2017) demonstrates that Wallabia is embedded within the large genus Macropus, necessitating reclassification of this species in the future.
Anthropogenic actions, such as the increase in roads through swamp wallaby habitats, are a threat to their survival. They are frequently seen near the side of roads, leading to a larger number becoming roadkill.[11]
Other sources of threat for the swamp wallaby are their predators, which include dingoes, eagles and wild dogs.[12]
The swamp wallaby (Wallabia bicolor) is a small macropod marsupial of eastern Australia. This wallaby is also commonly known as the black wallaby, with other names including black-tailed wallaby, fern wallaby, black pademelon, stinker (in Queensland), and black stinker (in New South Wales) on account of its characteristic swampy odour.
The swamp wallaby is the only living member of the genus Wallabia.
