SWAMP WALLABIES IN FRED CATERSON RESERVE

by Edwina Laginestra

Swamp Wallabies (Wallabia bicolor) are found right down the east coast of Australia from Cape York to Mt Gambier in South Australia. They are generally solitary and very shy so it is exciting when you see one, but they easily disappear into scrub if you blink. Their preferred habitat is thick bushy undergrowth of forests and woodlands and sandstone heath. 

There are 51 species of macropod (from Greek meaning “Big Foot”) which include kangaroos, wallabies, potoroos and bettongs. The Swamp Wallaby is more diurnal than other species and is often seen during the day. It gets the name from the “swampy smell” of its meat (which is also why it has the common name “stinker” in Queensland). 

Dark and stocky with dark grey or blackish fur above and underparts a pale yellow or orange gives them their scientific name “bicolor”. Their muzzle is mid-grey to blackish but gets paler with age and old wallabies can appear extensively white around the face. The forehead, crown and under the ears can be reddish, with black area around and behind the eyes and a whitish stripe from upper lip below the eye to the base of the ear. Paws and feet are black. It has a throaty growl to warn off threats and alarm is communicated by a foot stamp. They cough to communicate with each other. Males are larger than females and can get to 17-20kg, with a length from head to tail tip of up to 1.7m, females have an average weight of 13kg and length 1.5m.

They will aggregate into groups when feeding in open areas at night; they eat a wide range of plants, including shrubs, ferns, sedges and some grasses, and will also scratch the ground to find underground-fruiting fungi, and eat bark and leaves. They are more often seen browsing on shrubs than grazing on grasses and can tolerate a variety of plants that may be poisonous to others eg. bracken, and have been observed eating hemlock. Their molar tooth structure reflects the preference for browsing.

Photo: Ákos Lumnitzer

They vary from other macropods by their way of moving, their chromosomes and their embryonic diapause. Their gait differs from other wallabies as they carry the head low and tail out straight. The males have 11 chromosomes and females 10 chromosomes whereas other wallabies have 16. Females have an unusual form of embryonic diapause having a gestation period of 33-38 days, longer than their oestrus cycle of 34 days, so they can overlap 2 pregnancies, gestating an embryo and fetus at the same time. It is the only marsupial that has a gestation period longer than the oestrus cycle.

Females become fertile around 15-18 months of age and breed throughout the year. A single young will stay in the pouch until around 8-9 months and will be independent at 16 months. 

They face threats from land-clearing and roads built through their habitat and they are often seen by roadsides, leading to large numbers becoming roadkill. They are also vulnerable to domestic dog attack. They are no longer as common in Sydney as they once were but are still seen in Fred Caterson Reserve.