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 genus Macropus includes not only the large kangaroos but a range of mid-sized macropods known collectively at wallabies or brush wallabies. The exception is the Swamp Wallaby which is in its own genus Wallabia by virtue of its different chromosome number and other features. With the advent of agriculture and pastoralism the wallabies have fared less well than the kangaroos with most species in reduced ranges since European settlement. One species, the Toolache Wallaby (Macropus greyi) is extinct. In this pattern of range contraction, the Swamp Wallaby, is again an exception as it remains reasonably abundant in many peri-urban parks and reserves.

The Wallabies like the larger Kangaroos are predominantly grazers but may take some browse, especially the Swamp Wallaby. They share a similar body form and habits to the larger Kangaroos and are sympatric with Grey Kangaroos or the Antilopine Wallaroo in the north.

Species

Tammar Wallaby (Kangaroo Island)

Macropus eugenii decres

Best place to see

Flinders Chase National Park, South Australia

Flinders Chase National Park is on the south-western tip of Kangaroo Island and requires a short sea or air journey to reach from mainland South Australia. The Park has many natural and historical attractions and includes extensive coastal views as well as wilderness areas. The Tammar Wallaby may be seen in many parts of the Island (some where they are treated as a pest) but at Flinders Chase they are well-habituated to visitors especially around the Park Headquarters and Visitor Centre and camp ground. The Park is also the best place to see the Kangaroo Island Western Grey.

Identification

The Tammar Wallaby is less sexually dimorphic than most of the other brush wallabies. Males average 7.5 kg and reach 10 kg and females average 5.5 kg and reach 6 kg. The Kangaroo Island subspecies has a thicker fur and shorter ears than the mainland sub-species. The back is predominantly grey flecked with light tones but the shoulders and flanks are rufous (reddish brown). The underside is white to grey-white. The extremities of the limbs and tail are black. They have a cleft between the rhinarium of the nose and the upper lip (the latter is distinctly broad at the front). They are easily distinguished from the Western Grey Kangaroo by their small size.

Habitat

Ecotone between dense scrub and more open pasture.

Foraging behaviour

Predominantly grazer with some browse in the diet. Individuals share home ranges and may aggregate on foraging sites.

Reproductive behaviour

The reproductive physiology of the Tammar Wallaby is the best-studied of all the macropods and it has become a model for understanding the endocrinology of reproduction in marsupials. The species is strictly seasonal in breeding cued by the summer solstice. Like most other wallabies oestrus is post-partum and pouch life about 7 months so that pouch young emerge at about 8 months of age. The Tammar Wallaby has embryonic diapause and so for a primiparous (first birth) female, she will mate, give birth about 31 days later, mate again within one day of birth and this blastocyst will be held in utero in diapause. However, if the pouch young dies the diapausing blastocyst will not resume development until the female is cued by the passing of the summer solstice. This unusual seasonality has lead to the mistaken belief that all macropods are capable of holding a blastocyst in suspension, especially over drought for rangeland species. This is not true and confuses the Tammar Wallaby pattern with the exemplar of the Red Kangaroo.

Social organisation

Solitary in daytime shelters but aggregate on pasture at night.

Further readings

Lentle RG, Hume ID, Stafford KJ, Kennedy M, Springett BP, Haslett S (2005) The temporal organisation of feeding behaviour of four species of wallaby: examining chronobiological and homeostatic influences. Australian Journal Of Zoology 53, 117-129.

Hinds LA, Poole WE, Tyndale-Biscoe CH, van Oorshot RAH, Cooper DW (1990) Reproductive biology and the potential for genetic studies in the Tammar Wallaby, Macropus eugenii. Australian Journal Of Zoology 37, 223-234.

Rudd CD (1994) Sexual behaviour of male and female tammar wallabies (Macropus eugenii) at post partum oestrus. Journal of Zoology 232, 151-162.