Setonix brachyurus (Quoy & Gaimard, 1830)

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 : 721

43.

Quokka

Setonix brachyurus

French: Quokka / German: Quokka / Spanish: Ualabi de cola corta

Other common names: Short-tailed Pademelon, Short-tailed Wallaby

Taxonomy. Kangurus brachyurus Quoy & Gaimard, 1830 ,

“ le port du Roi-Georges [= King George Sound ], a la Nouvelle-Hollande [= Western Australia].”

Monotypic.

Distribution. Patchily distributed in far SW Western Australia from E of Perth to Stirling and Green Ranges E of Albany; also Rottnest and Bald Is.

Descriptive notes. Head-body 43-54 cm (males) and 39-50 cm (females), tail 25-31 cm (males) and 23.5-28.5 cm (females); weight 2.7-4.2 kg (males) and 1-6— 3-5 kg (females). Body size decreases with latitude. Small, stocky, short-faced wallaby with short rounded ears and short tail. Grizzled grayish brown dorsally, paler ventrally. Fur thick and coarse. Head, neck, and shoulders sometimes washed with rufous. Tail dark and lightly furred, sometimes paler ventrally. Diploid chromosome numberis 22.

Habitat. Forest, woodland, swamps, riparian zones, wetland fringes, shrubland, and heathland where annual rainfall greater than 700 mm. Mainland populations now largely confined to areas where annual rainfall exceeds 1000 mm, with dense groundlevel vegetation (e.g. shrubs, rushes, sedges) and a mix of recently burnt and longunburnt fire histories. On Rottnest Island present also in highly modified habitats, including urban areas.

Food and Feeding. Mostly a browser, consuming leaves and stems of a broad but select range of shrubs. Species composition varies among sites and seasonally, with new growth often preferred. In studies at mainland sites, 29 species were consumed, but only eleven shrub species comprised 90% of diet, with more fleshy species preferred; 40 species consumed on Rottnest Island, where diet dominated by saltbush and other succulents, particularly in summer, with grasses, browse, forbs, and sedges also consumed in varying proportions depending on season and location, but only eight species (seven dicotyledonous and one monocotyledonous) preferred. Food also regularly scavenged from humans and rubbish dumps on Rottnest Island. Reported to browse on seedlings in exotic pine plantations on mainland. Also reported to climb into shrubs to reach foliage and occasionally to consume gastropod mollusks.

Breeding. Sexual maturity is reached from nine months in females and 13 months in males. Females are continuous breeders on mainland, typically producing one young per pregnancy, but occasionally twins. On Rottnest and Bald Islands breeding seasonal, with most young born January-March and females anestrous for much of year. This seasonality breaks down in captivity, indicating that anestrus is environmentally induced (e.g. by nutritional stress). Females exhibit embryonic diapause and postpartum estrus, mating shortly after giving birth. Estrous cycle is ¢.28 days and gestation ¢.27 days. Young spend 6-6-5 months in the pouch and are weaned at around eight months. After permanent pouch emergence, young accompanies the mother as a young-at-foot until after weaning and may continue to associate with her until 19-20 months. During late summer/autumn, individuals on Rottnest Island experience severe nutritional and water stress; mortality is often high, especially among juveniles. Mating system appears to be promiscuous, and estrous females have been reported as mating with up to five different males. Adult males are larger than adult females, and there is intense competition among males for access to females. Males vigorously guard estrous females by chasing and/or attacking other interested males before (and sometimes also after) copulation guarding or copulating subordinate males are frequently displaced by a more dominant male, and forced copulations sometimes occur. Females exercise some choice by refusing to mate with some males or hopping away when attendant males are distracted. Copulation typically occurs over 2—4 minutes but may last up to eleven minutes, and can occur up to nine times with a single male. After copulation males often lose interest in the female, and she may then mate with additional males.

Activity patterns. Mostly nocturnal, spending the day resting in dense vegetation; sheltering mainly under shrubs ( Acanthocarpus preissii , Asparagaceae ; Melaleuca lanceolata , Myrtaceae ; Acacia rostellifera , Fabaceae ; Westringia dampieri , Lamiaceae ) on Rottnest Island in summer. Becomes active late afternoon to early evening and forages throughout night, with peaks in early evening and prior to dawn as it returns to shelter. Activity on Rottnest Island inhibited by heavy rain and bright moonlight.

Movements, Home range and Social organization. Highly sedentary. On the mainland, moves along well-established runways through dense vegetation and rarely forages far from dense cover. In drier months (summer and autumn), however, relatively more open areas are used for foraging. Resting sites are located close to wherever nocturnal foraging ceases. Home-range (95% minimum convex polygon) estimates on mainland were similar in males and females (5 ha), but differed among sites and tended to be larger in drier months. On Rottnest Island, each individual regularly uses a small number of resting sites under shrubs or in thickets, and regularly forages in the open between 50 m and 600 m from resting site. Adults on Rottnest will make excursions of up to 2 km from their home range to visit freshwater soaks or garbage dumps. Home ranges on Rottnest overlap with those of others (members of both sexes). Males vigorously defend and exclude other males from resting sites, although such sites may be shared by multiple females or by a male and one or two females. Males establish local dominance hierarchies through fighting, with older/heavier individuals usually ranked highest. On Rottnest Island large aggregations (more than 100 individuals) occur at resource-rich sites (e.g. freshwater soaks). Social organization poorly understood. Appears not highly social, often rests and forages alone; long-term associations between some adult males and females have, however, been reported. Dispersal appears limited, mostjuveniles settling within 100 m of natal home range, although one individual moved 900 m. Longer-distance movements (up to 10 km) of adults occasionally reported.

Status and Conservation. Classified as Vulnerable on The IUCN Red List and in Australia. In early 1900s the Quokka was sufficiently widespread and abundant in southwestern Western Australia to be regularly hunted and actively persecuted as an agricultural pest. Previously found from Jurian Bay (north of Perth) to Bremer Bay, on south coast of Western Australia. Since 1930s, mainland populations have declined dramatically, both in range and in abundance. The species now occurs mostly at low density and is rarely seen. The current distribution is highly fragmented, many remaining populations small, isolated, and continuing to decline. Major causes of decline are habitat loss due to clearing for agricultural and urban development, altered fire regimes, and predation by introduced Red Fox (Vulpes vulpes). In many areas, habitat loss and degradation caused by clearing, logging, altered fire frequency, hydrological changes, and foraging activity of feral pigs are continuing. Nevertheless, some Quokka populations have increased under fox control, and feral-pig control is undertaken is some areas. Quokkas are vulnerable also to continuing reductions in rainfall under climate change. Predation by domestic/feral cats (Felis catus) and roadkill may also be a threat to some populations. The largest surviving population of this macropodid is on Rottnest Island, where Quokkas are a conspicuously abundant tourist attraction, although numbers fluctuate widely with seasonal conditions. All sampled populations appear to have low genetic diversity, although island and mainland populations are differentiated. Those on Rottnest appear to have benefited from past habitat disturbances and, in some areas, availability of freshwater; as a consequence they may now be overabundant on Rottnest, limiting the regeneration of native vegetation. Quokkas occur in a number of protected areas, and are well established in captivity. A recovery plan has been prepared. Additional studies of this species’ population biology and ecology, as well as behavior and reproduction of mainland populations, the impact of potential threats, and the success of threat mitigation, are required.

Bibliography. Abbott & Burbidge (1995), Alacs et al. (2011), DEC (2013), Dunnet (1962), Erickson (1951), Gibson et al. (2010), Hayman (1989), Hayward (2005), Hayward, de Tores, Augee & Banks (2005), Hayward, de Tores, Augee, Fox & Banks (2004), Hayward, de Tores & Banks (2005), Hayward, de Tores, Dillon & Banks (2007), Hayward, de Tores, Dillon & Fox (2003), Herbert (2007), Holsworth (1964, 1967), Kitchener (1972, 1973), Main (1959), Main et al. (1959), McLean & Schmitt (1999), McLean et al. (2009), Menkhorst & Knight (2001), Nicholls (1971), Packer (1965, 1969), Poole et al. (2014), Sinclair (1998, 2001), Sharman (1955a, 1955b), Shield (1964, 1968), Stewart (1936), Storr (1964a, 1964b, 1964c), de Tores (2008b), de Tores, Burbidge et al. (2008), de Tores, Hayward et al. (2007), Woinarski et al. (2014b).

Figures

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

Distribution. Patchily distributed in far SW Western Australia from E of Perth to Stirling and Green Ranges E of Albany; also Rottnest and Bald Is.