Petrogale penicillata (Gray, 1827)

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 : 715-716

35.

Brush-tailed Rock Wallaby

Petrogale penicillata

French: Wallaby a pinceau / German: Birsten-Felskdnguru / Spanish: Ualabi rupestre de cola de cepillo

Other common names: Brush-tailed Rock-wallaby

Taxonomy. Kangurus penicillatus Gray, 1827 ,

Sydney, New South Wales, Australia.

A member of the lateralis / penicillata group of species (which includes also P. rothschaldi, P. lateralis , P. purpureicollis , P. herberti , P. inornata , P. assimilis , P. sharmani , P. mareeba , P. godmani , P. coenensis ). Formerly contained P. herberti as a subspecies. This species consists of three Evolutionarily Significant Units (ESUs). Monotypic.

Distribution. Patchily distributed on E side of Great Dividing Range from N of Brisbane, Queensland, to Kangaroo Valley, New South Wales. Small isolated populations persist W of the Great Dividing Range in N New South Wales (in the Warrumbungles and at Mt Kaputar) and in E Victoria (East Gippsland).

Descriptive notes. Head-body 52-8 61.5 cm (males) and 51-57 cm (females), tail 48-70 cm (males) and 50-63 cm (females); weight 4:-4-10.9 kg (males) and 4.2-8.2 kg (females). Dark brown dorsally, tending to rufous on rump and gray on shoulders. Chest and belly paler, some individuals having distinct white blaze on chest. Pale cheek stripe, black dorsalstripe from forehead to back of head, ears black toward tips. Black axillary patch often extending as dark stripe to margin of legs. Pale gray side stripe sometimes present. Feet and paws dark brown to black. Tail darkens distally, with prominent brush. Pelage long and thick, particularly about rump, flanks, and base of tail. Animals from north of range tend to be grayer,less distinctly marked, and have less prominent tail brush. Diploid chromosome number is 22.

Habitat. Rocky outcrops, boulder piles, cliffs, gorges, and rocky slopes in rainforest gullies, wet and dry sclerophyll forest, as well as grassy and semi-arid woodland. Occurs also in low, dense vegetation (e.g. dry rainforest and vine thickets) on steep slopes adjacent to more open grassy areas.

Food and Feeding. Consumes a broad mix of plants: grasses, forbs, browse, trees, climbers, orchids/lilies, sedges, and ferns. Selection of dietary components varies across the geographical distribution and with season, but grasses, forbs, and browse are generally preferred. Seeds and fruit often consumed and flowers eaten occasionally.

Breeding. Sexual maturity is reached at c.18 months in females and 23 months in males. Females breed throughout year, producing one young per pregnancy, although there is a peak in births in autumn in many populations. Females exhibit embryonic diapause and post-partum estrus, usually mating shortly after giving birth. Length of estrous cycle has not been determined, but gestation period is ¢.32 days. Young spend 6-5-7 months in the pouch and are usually weaned by eight months, although they continue to associate with the mother for several more months. In one study, 26% of young failed to survive pouch life, those born in autumn or winter having higher chance of surviving to pouch emergence. Breeding system appears polygynous, males mating with multiple females but females showing serial mate fidelity. Males do not achieve paternity until they are more than 5 kg.

Activity patterns. Largely nocturnal in summer, crepuscular or partially diurnal in other months. Typically spends day in a shelter site (crevice, crack, cavity, ledge, small cave) among rocks or within a boulder pile. May also shelter in more exposed locations, including between boulders, in dense vegetation, in hollow logs, at base of trees, and on branches. Individuals tend to use and defend same shelter, or small group of sheltersites, for many years, preferring particular sites at different times of the year. In late afternoon emerges to bask in the sun on exposed rocks before moving off to forage. During heavy rain, high wind, bright moonlight, or low temperatures, activity may be reduced, individuals returning to dens before midnight. Before dawn, returns to rocks and may bask in sun for many hours (sometimes all day in cooler weather) before retreating to den site.

Movements, Home range and Social organization. May travel more than 400 m to feed in open grassy areas. Estimates of nocturnal foraging ranges were 2 ha for females and 3 ha for males (100% minimum convex polygon), while at another site home-range size varied from 16 ha to 42 ha (mean 28 ha; 95% adaptive kernel). Home ranges show extensive overlap among individuals of both sexes, although daytime dens seem to be relatively exclusive and are defended. Although individuals typically shelter alone during day, the sharing of shelters by two females, a mother and young or a male and female is occasionally reported. At somesites, the shelter area of males is larger than and overlaps with those of several females. Two males have not been observed to share a shelter, and typically avoid each other both near sheltersites and when foraging. In captivity, males are aggressive toward one another, especially if females are present. Females are more social but can be highly aggressive toward one another, both in the wild and in captivity. Occurs in colonies of up to 70 individuals, and both behavioral and genetic studies indicate that populations are highly structured. Multiple distinct social/genetic groups occur even in relatively small areas of habitat (e.g. 800 m of cliff line). Dispersal, although male-biased, appears to be highly limited. Female offspring settle within or close to the mother’s home range, while young males disperse farther but still may notleave their natal colony, resulting in clusters of related females occupying separate areas and associating with a limited number of unrelated males. Dispersal between colonies appears to be extremely rare, populations 2-3 km apart showing significant genetic differentiation.

Status and Conservation. Classified as Near Threatened on The IUCN Red List. Listed as vulnerable in Australia. This rock wallaby was formerly widespread in south-eastern Australia from south-east Queensland to western Victoria, but in the last 150 years has declined significantly throughout its range, with many local extinctions. This decline in distribution and density is continuing. Brush-tailed Rock Wallabies were previously highly abundant, with hundreds of thousands killed as supposed agricultural pests and for the fur trade in late 1800s and early 1900s. Their subsequent decline has been most severe in the southern and western parts of range, severely impacting the southern and central ESUs. The northern ESU has also declined, but remains locally common in parts of northern New South Wales and south-east Queensland. Brush-tailed Rock Wallabies (southern ESU) were thought to be extinct in Victoria until 1953, when several colonies were rediscovered in East Gippsland and then in the Grampians, western Victoria, in 1970. By 2000, however, all but one of these southern ESU populations had become extinct. The species is now extinct also west of the Great Dividing Range, apart from some highly vulnerable remnant populations in the Warrumbungles and at Mount Kaputar. Elsewhere in New South Wales and Queensland,it is now largely confined to scattered and often remote sites that are typically geologically highly complex, containing many shelter sites with multiple escape routes. Brush-tailed Rock Wallabies occur in many protected areas, but surviving populations are often very small (fewer than ten adults), have low genetic diversity, are inbred, and remain highly prone to extinction. Several state and national recovery plans have been prepared. The historic and current causes of the Brush-tailed Rock Wallaby decline appear complex and multifactorial. Hunting was a significant historical factor, but introduced competitors, such as sheep, rabbits, and feral goats, and predators, such as Red Fox (Vulpes vulpes), appear to be major contemporary threats. Habitat loss, fragmentation, and degradation are also likely contributors. Altered fire regimes and competition from other macropodids could be additional factors at some sites. Further research into the relative importance of threats, their potential interaction (s), and the effectiveness of current mitigation strategies is urgently required. Existing conservation measures include fox and goat control, captive-breeding, supplementation of small colonies, and reintroductions to extinctsites. While some local populations have increased as a result of establishment of predator control, others appear not to have responded. Reintroduction efforts have also had mixed success,this being due to a variety of factors, including fox predation. Brush-tailed Rock Wallabies were successfully introduced to several islands in New Zealand during 1870s. They were also accidently released on Oahu, in Hawaiian Islands, in 1916 and successfully established themselves. Commencing in 1990s, populations of this wallaby in New Zealand have been targeted as part of a conservation program to eradicate introduced species. Brush-tailed Rock Wallabies, derived mainly from introduced New Zealand populations, are held in zoos throughout the world. In Australia, captive populations have recently been established, mostly from wild-caught individuals, for both southern and central ESUs. These have been used for education and as a source of animals for conservation initiatives. For the critically endangered southern ESU, cross-fostering of pouch young has been used as a means of accelerating the rate of reproduction of captive females. Additional research on impact of threats and effectiveness of current mitigation strategiesis required.

Bibliography. Batchelor (1980), Bluff et al. (2011), Browning et al. (2001), Bulinski et al. (1997), Carter & Goldizen (2003), Close et al. (1988), DECC (2008b), Dovey et al. (1997), DSE (2003), van Eeden et al. (2011), Eldridge (1997), Eldridge & Browning (2002), Eldridge & Close (1992, 2008f), Eldridge, Bell & Wong (1997), Eldridge, Browning & Close (2001), Eldridge, Rummery et al. (2004), Hazlitt, Eldridge & Goldizen (2004, 2010), Hazlitt, Goldizen & Eldridge (2006), Hazlitt, Goldizen, Nicholls & Eldridge (2014), Hazlitt, Sigg et al. (2006), Jarman & Bayne (1997), Joblin (1983), Laws & Goldizen (2003), Lunney et al. (1997), Menkhorst & Hynes (2011), Molyneux et al. (2011), Mowbray (2002), Piggott, Banks, Stone et al. (2006), Piggott, Banks & Taylor (2006), Potter, Cooper et al. (2012), Scholz (1980), Schultz et al. (2006), Sharman et al. (1989), Shaw & Pierce (2002), Short (1980, 1982, 1989), Short & Milkovits (1990), Soderquist (2011), Taggart, Menkhorst & Lunney (2008), Taggart, Schultz et al. (2005), Tuft et al. (2011, 2012), Wakefield (1954, 1961, 1971), Woinarski et al. (2014aw), Wynd etal. (2006).

Figures

34. Purple-necked Rock Wallaby (Petrogale purpureicollis), 35. Brush-tailed Rock Wallaby (Petrogale penicillata)

Distribution. Patchily distributed on E side of Great Dividing Range from N of Brisbane, Queensland, to Kangaroo Valley, New South Wales. Small isolated populations persist W of the Great Dividing Range in N New South Wales (in the Warrumbungles and at Mt Kaputar) and in E Victoria (East Gippsland).