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

Agile Wallaby

Macropus agilis ('agile long-foot')

Best place to see

East Point Reserve, Darwin, Northern Territory

East Point Reserve is a 200 ha coastal reserve in the heart of Darwin. It has long been a recreational area offering picnic facilities and safe swimming. There are cultural attractions (military history) as well as a good representation of the flora and fauna of the Darwin region. The ongoing development of Darwin city and the increasing urbanisation has brought some conflict with the Agile Wallaby population at the Reserve and consequent changes in land management. Urban planning and the accommodation of wildlife, especially large mammals, has resulted in dissention when lethal control measures for the wildlife are invoked. Managed parklands with well-watered lawns and permanent water sources provide attractive habitat to many adaptable kangaroo and wallaby species and they can become isolated without planning for wildlife corridors through valuable urban real estate. These populations grow and faecal contamination of lawns becomes unattractive to recreational users and the kangaroos or wallabies suffer from dog attacks and collisions with vehicles.

These issues were confronted at East Point Reserve through a 3-year research project and more favourable management adopted. The Agile Wallabies remain a key attraction and allow close observation. The species is widespread across northern Australia and can be seen in many national parks and reserves.

Identification

The Agile Wallaby is a mid-sized species with males reaching 27 kg and females 15 kg. The back colouration is sandy brown and may appear reddish in some populations. The underside is light coloured and generally white. They have two distinctive head features: a dark stripe down the midline between to ears to the eyes and a light colour cheek-stripe. They also have a distinctive light stripe on the thighs. The margins of the ears and the tail tip are black.

Habitat

The Agile Wallaby is the most common macropod in tropical Australia and is confined mostly to coastal regions in the east in Queensland but extends well into the hinterland of the Northern Territory and Western Australia. The species is also found on the southern and eastern lowlands of Papua New Guinea and thus its distribution spans the Torres Strait. The Agile Wallaby is usually found near permanent water in wetlands, along rivers and large creeks with springs billabongs (water-holes) in the Dry season. Thus it ranges out from riparian vegetation into adjacent grassland and tropical savannah.  Home ranges therefore encompass diurnal shelter in monsoon rainforest, vine forest or other thick vegetation and nocturnal foraging areas in more open habitat including roadside verges. The latter are often mowed and/or burnt and provide good foraging habitat so drivers need to be cautious at night where Agile Wallabies are abundant.

 

During the Wet season its preferred habitat of floodplains becomes inundated and Agile Wallabies retreat to higher ground taking them into the base of escarpments and hills. Agile wallabies are attracted to green pick (shooting grasses) after fire and may share this resource with Antilopine Wallaroos. They are typically found in dense cover during the day and range out into more open areas at dusk and through the night. However, they are not strictly nocturnal and will forage during the day in overcast conditions found in the Wet season.

Foraging behaviour

In clear weather, Agile Wallabies forage at night but under overcast conditions they are less constrained and may be seen foraging in the day. Foraging effort increases in the Dry season when forage quality declines and this may be at the cost of other activities like vigilance and grooming. The foraging area also expands to encompass open and closed habitat. In the Wet season they are more flexible and may forage on overcast days but in neither season do they rest much at night.

 

Agile wallabies are primarily grazers in the Wet season when the preferred diet of grasses and legumes provide sufficient protein and energy and are highly digestible. In the Dry season the diet broadens to include browse, fallen leaves, fruit, flowers and the wallabies may dig up roots and strip bark from some shrubs and trees. The wallabies may lose body condition during the Dry season as a result of nutritional stress. In coastal areas they will graze on dune vegetation and eat the stolons of sand spinifex.

Reproductive behaviour

The Agile Wallaby is sexually dimorphic with males reaching twice the size of females and having stronger forelimbs. Breeding is aseasonal, pouch life is 7-8 months and young are weaned at 10-12 months. Oestrus is post-partum and embryonic diapause occurs so this species shows that classic Red Kangaroo breeding pattern. However, pouch young are not lost so much through drought but one suggestion was that they are drowned while their mothers swim out of inundated areas. This is not proved but mortality of pouch young certainly occurs and high fecundity through the quiescent blastocyst offsets this.

 

Male sexual behaviour is also typical of the genus with males sniffing the cloaca of females, grasping their tails, standing in front of them and blocking their forward progression, and touching the female's head and body. One characteristic not shared with the large kangaroos is sinuous tail lashing which is quite frequent and obvious in Agile Wallabies. The behaviour occurs in a number of contexts when individuals are thwarted or tentative in their activities.

 

Courtship is brief and competition for mates does not seem to be intense although the consort male is typically a large individuals. Play-fighting amongst males is common with extended episodes of kicking. Unlike the large kangaroos the tail is not used as a support when kicking and rather males leap into the air. This lack of use of the tail as a support is characteristic of the wallabies as is sinuous tail movements. It seems that the large kangaroo which support their bulk with the tail have lost some mobility in it as it is typically grounded an unable to move sinuously. Males male also grapple and pull at vegetation in some confrontations but this behaviour is not strictly interactional and occurs when males are solitary.

Social organisation

Agile Wallabies are variously described as solitary or gregarious. It seems associations between individuals are facultative depending on forage conditions and relationships between sexes are transient. The mother-young relationship is also relatively short and young are quickly weaned. Individuals are often seen alone in dense cover but larger aggregations occur on open pasture. Dingos are common in the tropics and will prey on Agile Wallabies and thus aggregations may benefit anti-predator behaviour through group vigilance. Even so when aggregations are disturbed individuals flee into cover in scattered and seemingly uncoordinated directions.

 

Agile Wallabies do not maintain exclusive home ranges and there is overlap within and between the sexes. Even so core areas overlap more in females than males. Home range areas were estimated for the East Point Reserve at 16.6 and 11.3 ha for males and females, respectively, in the Wet season. Home ranges expanded in the Dry season to 24.6 and 15.3 ha for males and females, respectively. The larger Dry season home ranges are attributed to poorer foraging conditions and a greater search area for food items.

 

The social behaviour of Agile Wallabies is typical of the larger macropods and observers would expect to see sexual checking by males towards females, male-male sparring bouts and mother-young interactions with large pouch young and young-at-foot. Agile Wallabies tend to be highly vigilant and are said to have a nervous disposition often repeatedly stamping their feet (foot-thumping) when alarmed.

 

Further readings

Stirrat SC, Fuller M (1997) The repertoire of social behaviours of agile wallabies, Macropus agilis. Australian Mammalogy 20, 71-78.

Stirrat SC (2002) Foraging ecology of the agile wallaby (Macropus agilis) in the wet-dry tropics. Wildlife Research 29, 347-361.

Stirrat SC (2003) Seasonal changes in home-range area and habitat use by the agile wallaby (Macropus agilis). Wildlife Research 30, 593-600.

Stirrat SC (2004) Activity budgets of the agile wallaby, Macropus agilis. Australian Journal of Zoology 52, 49-64.