Wallabia bicolor (Desmarest, 1804)

Russell A. Mittermeier & Don E. Wilson, 2015, Macropodidae, Handbook of the Mammals of the World – Volume 5 Monotremes and Marsupials, Barcelona: Lynx Edicions, pp. 630-735 : 723

46.

Swamp Wallaby

Wallabia bicolor

French: Wallaby bicolore / German: Sumpfwallaby / Spanish: Ualabi de pantano

Other common names: Black-tailed Wallaby; Black Stinker (New South Wales), Black Wallaby (Victoria), Stinker (Queensland)

Taxonomy. Kangurus bicolor Desmarest, 1804 ,

no type locality given.

Shows considerable morphological differentiation across its range and up to five subspecies have been commonly, although tentatively, recognized. Since a comprehensive study of intraspecific variation is yet to be undertaken, it is considered premature to treat this species as polytypic. Monotypic.

Distribution. Coastal and subcoastal E Australia from Cape York Peninsula, NE Queensland, to far SE South Australia and inland to Adavale, Queensland; present also on islands of Fraser, Bribie, North and South Stradbroke, Peel, and Russell (all in Queensland), as well as Chinaman, Hummock, Little Snake, Phillip, Rotamah, and Sunday (all in Victoria).

Descriptive notes. Head—body 72:3-84.7 cm (males) and 66.5-75 cm (females), tail 69-86.2 cm (males) and 64-72.8 cm (females); weight 12:3-20.5 kg (males) and 10.3-15.4 kg (females). Large, typically dark, stocky, coarse-furred wallaby, but highly variable in coloration and markings. In south of range: dark grayish brown to blackish brown (occasionally reddish) dorsally, heavily flecked with gray, yellow, and rufous, and paler rufous-orange to yellow ventrally; pale cheek stripe of variable length and intensity, dark grayish face, blackish around eyes; forehead, crown, and base of ears rufous; indistinct mid-dorsal stripe on forehead occasionally present; ears dark, sometimes with pale margins; limbs paler than body and more gray, yellow or rufous, but paws and feet black; black axillary patch, typically without pale flecking; tail similar in color to body proximally, but dark distally, occasionally with white tip. Individuals become more richly colored (rufous or yellow), distinctly marked, and paler with decreasing latitude; frequency of white tail tip also increases northward. Some northern individuals pale silvery gray, flecked with yellow dorsally, pale yellow ventrally, with strongly contrasting black axillary patch, paws, feet, and tail; broad pale yellow cheek stripe contrasting strongly with dark face and light rufous forehead and crown; ears dark but margins pale and silvery, especially toward tips. In addition, a golden color morph occurs in south-east Queensland, rarely reported from mainland but is common on North and South Stradbroke Islands. Diploid chromosome number is 11 in males and 10 in females.

Habitat. Forest and woodland, often with dense canopy cover, and almost always with dense understory of young trees, shrubs, sedges, or ferns, including remnant patches and strips retained after timber-harvesting. Occurs also in shrubland, heathland, regenerating eucalypt forest, pine plantations, and roadside vegetation; also coastal dunes on South Stradbroke Island. Particularly favors dense cover and browse provided by early stages of regrowth after timber-harvesting and fire, and by young timber plantations and rehabilitation plantings (individuals are largely unaffected by timber-harvesting or fire events). Can occupy peri-urban habitat patches, and will use underpasses and overpasses to cross roads. Rarely occurs in swamps, despite its common name.

Food and Feeding. A generalist herbivore, consuming a wide range of foods, including at least 77 plant genera. Diet composition is dominated by leaves and stems of shrubs and forbs in understory and ground layers across its geographical range. Tree seedlings, vines, grasses, sedges, rushes, ferns, and fruiting bodies of hypogeous and epigeous fungi are also consumed. Shrubs and forbs appear to be preferred, but some spatial and seasonal differences have been recorded. Has been reported to feed also on the bark of introduced pine trees and on brown algae in tidal shallows.

Breeding. Both sexes reach sexual maturity at 15-18 months. Breeds continuously throughout year, females producing one young per pregnancy. The estrous cycle is 29-34 (mean 31) days and gestation 33-38 (mean 37) days. Exhibits embryonic diapause and, unusually, has a pre-partum estrus, mating up to 8 days before giving birth. Young spend 8-9 months in the pouch and are weaned at c.15 months. After permanent pouch emergence, young stays hidden in dense cover for several days and the mother returns briefly to suckle it; later it accompanies the mother as a young-at-foot until after weaning. Adult males are larger than adult females and often carry wounds to the face and ears, suggesting strong competition among males for access to females.

Activity patterns. Largely nocturnal, although its preference for dense cover limits observations of daytime activity. Selects food-rich patches at night, sometimes emerging before sunset to feed in open areas. Activity declines steadily throughout night, and is lowest under bright moonlight. Sometimes feeds on pasture, at least 30 m from dense cover.

Movements, Home range and Social organization. Sedentary, occupying small, overlapping home ranges, averaging 16 ha (100% minimum convex polygon MCP) for both sexes at one site and 33 ha (95% harmonic mean) at another, where ranges in productive roadside habitat (16 ha) were smaller than in a reserve (43 ha). Males (38 ha) had much larger ranges (95% adaptive kernel) than females (17 ha) at anothersite, where range size was inversely related to patchiness of shelter and foraging resources. Average home range (100% MCP) was even larger (98 ha) at a site disturbed by fire. Essentially solitary; occasionally forms aggregations when feeding in open habitat. Dispersal is male-biased, and extensive gene flow has been detected between habitat patches separated by 10-17 km of cleared land.

Status and Conservation. Classified as Least Concern on The [UCN Red List. The Swamp Wallaby is widespread and common through much ofits range, and occurs in multiple protected areas. Once rare in south-eastern South Australia, it is now more common and is extending its range westward. It has expanded its range also in western Victoria and the Australian Alps. This species was first reported in the Grampians National Park in 1979, and is now common throughout the area. It has since occupied many other areas in west of Victoria, probably taking advantage of extensive conversion of cleared pasture to Tasmanian blue gum ( Eucalyptus globules , Myrtaceae ) plantations. Population on Phillip Island, Victoria, is also increasing rapidly. The Swamp Wallaby is considered a pest in some agricultural and forestry areas, and is occasionally culled to reduce impacts on pasture and plantations. Browsing by this macropodid poses a threat to some conservation reserves and revegetation areas, but may also suppress invasive shrubs such as bitou bush (Chrysanthemoides monilifera, Asteraceae ). Additional research on taxonomy and reproduction is required, as well as ecological studies in northern half of its range.

Bibliography. Abbott & Burbidge (1995), Aitken (1983), Ben-Ami & Ramp (2013), Bennett & Coulson (2014), Bird (1981, 1992), Bond & Jones (2008), Calaby & Grigg (1989), Calaby & Poole (1971), Carpenter & Brandle (2009), Claridge et al. (2001), Davis et al. (2008), Dexter et al. (2013), Di Stefano & Newell (2008), Di Stefano, Anson et al. (2007), Di Stefano, Coulson et al. (2011), Di Stefano, Swan et al. (2010), Di Stefano, York et al. (2009), Edwards & Ealey (1975), Evans et al. (2005), Floyd (1980), Garnick et al. (2014), Garvey et al. (2010), Green & Osborne (2002), Green et al. (2014), Hayman (1989), Hradsky (2014), Hradsky et al. (2015), Hill & Phinn (1993), Hollis et al. (1986), Jarman (1991), Johnson (2003), Kaufmann (1974a), Kirkwood & Johnston (2006), Lavery (1985), Lindenmayer, Cunningham et al. (1994), Lindenmayer, McCarthy et al. (2000), Lunney & O'Connell (1988), Menkhorst & Knight (2001), Menkhorst, Denny, Ellis et al. (2008), Merchant (2008b), Montague (1996), Osawa (1990), Paplinska, Eldridge et al. (2009), Paplinska, Moyle et al. (2006), Ramsey & Engeman (1994), Schmidt et al. (2010), Stutz et al. (2014), Swan et al. (2008), Troy & Coulson (1993), Troy et al. (1992), Wood Jones (1924).

Figures

43. Quokka (Setonix brachyurus), 44. Rufous Hare Wallaby (Lagorchestes hirsutus), 45. Spectacled Hare Wallaby (Lagorchestes conspicillatus), 46. Swamp Wallaby (Wallabia bicolor)

Distribution. Coastal and subcoastal E Australia from Cape York Peninsula, NE Queensland, to far SE South Australia and inland to Adavale, Queensland; present also on islands of Fraser, Bribie, North and South Stradbroke, Peel, and Russell (all in Queensland), as well as Chinaman, Hummock, Little Snake, Phillip, Rotamah, and Sunday (all in Victoria).