Swamp Wallaby
(wallabia bicolor)
Geographic Range
The swamp wallaby can be found on the eastern coast of Australia from southeastern South Australia, Victoria, eastern Queensland, and eastern New South Wales.
Habitat
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.
Physical Description
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 hind limbs, contain five digits and are used for eating and slower movements. The hallux is absent in the hind limbs which are syndactylous and elongated for use in rapid bipedal motion. The fourth toe is the longest and the most specialized digit of the hind foot. 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.
Reproduction
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.
Behavior
Swamp wallabies are solitary, nocturnal animals. They have been found to gather at common food sources with other unrelated animals without showing signs of territorial defense. Wallabia bicolor have no known natural enemies. They are able to hop bipedally on their hind feet while holding their heads close to the ground. They may also use their forefeet to move around on all fours.
Food Habits
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.
Conservation Status
A decrease in the abundance of swamp wallabies has occurred 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.
Other Comments
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.
http://animaldiversity.ummz.umich.edu