Animal Diversity Web

Ge­o­graphic Range

Na­tive to Aus­tralia, brush-tailed rock-wal­la­bies are dis­trib­uted along rocky es­carp­ments of the Great Di­vid­ing Range from south­ern Queens­land to west­ern Vic­to­ria. Al­though com­mon in south-east­ern Queens­land and north­ern New South Wales, pop­u­la­tions in the south­ern and west­ern parts of the range have de­clined. Rem­nant pop­u­la­tions in Vic­to­ria and west­ern New South Wales are en­dan­gered. Only three colonies in south-east­ern Aus­tralia re­main, and es­ti­mates of the total wild pop­u­la­tion in this re­gion are at fewer than 12 in­di­vid­u­als. (El­dridge and Close, 1995; Tag­gart, et al., 2005)

Pet­ro­gale peni­cil­lata was in­tro­duced to Hawaii and New Zealand. In Hawaii, a small pop­u­la­tion of rock-wal­la­bies, de­scended from two an­i­mals, has ex­isted on the is­land of Oahu since 1916. In New Zealand, brush-tailed rock-wal­la­bies were in­tro­duced in the 1870s and can be found on Kawau, Ran­gi­toto, and Mon­tu­tapu is­lands. On some of these is­lands rock-wal­la­bies are reg­u­larly culled be­cause they have reached pest pro­por­tions. (El­dridge and Close, 1995; Tag­gart, et al., 2005)

• Biogeographic Regions
• australian
  • native
• oceanic islands
  • introduced

Habi­tat

Brush-tailed rock-wal­la­bies live on rock faces close to grassy areas and often in open forests. They pre­fer sites with nu­mer­ous ledges, caves, and crevices. They typ­i­cally oc­cupy sites with a northerly as­pect, in order to sun them­selves in the morn­ing and the evening. Orig­i­nally wide­spread and abun­dant, brush-tailed rock-wal­la­bies were found in suit­able rocky areas in a wide va­ri­ety of habi­tats, in­clud­ing rain­for­est gul­lies, wet and dry scle­ro­phyll for­est, open wood­land, and rocky out­crops in semi-arid coun­try. (Cronin, 2000; El­dridge and Close, 1995)

• Habitat Regions
• temperate
• tropical
• terrestrial

• Terrestrial Biomes
• savanna or grassland
• forest
• rainforest
• scrub forest

• Other Habitat Features
• caves

Phys­i­cal De­scrip­tion

Pet­ro­gale peni­cil­lata has a dull-brown back, paler chest and belly, a ru­fous rump and black, furry feet. They have a black ax­il­lary patch often ex­tend­ing as a dark stripe to the mar­gin of the hindlegs. Their tail dark­ens dis­tally with a promi­nent brush. Their pelage is long and thick, es­pe­cially about the rump, flanks and base of tail. An­i­mals from the north­ern part of the range tend to be lighter and have a less promi­nent tail brush. They have long tails, slightly longer than their head and body length. Head and body length av­er­ages 55.7 cm in males and 53.6 cm in fe­males, while tail length av­er­ages 61.1 cm in males and 56.3 cm in fe­males. (Cronin, 2000; El­dridge and Close, 1995)

• Other Physical Features
• endothermic
• homoiothermic
• bilateral symmetry

• Sexual Dimorphism
• male larger

• Range mass

  4.0 to 10.9 kg

  8.81 to 24.01 lb

• Range length

  45 to 58.6 cm

  17.72 to 23.07 in

Re­pro­duc­tion

Brush-tailed rock-wal­la­bies breed year round. The few mat­ings that have been ob­served among Pet­ro­gale peni­cil­lata in­volve only fe­males and males who are es­tab­lished on refuges. A no­table fea­ture of brush-tailed rock-wal­la­bies, as well as other Pet­ro­gale species, is close and reg­u­lar as­so­ci­a­tion be­tween the refuge-guard­ing male and the fe­males who use his refuge. As­so­ci­a­tion in­volves mu­tual groom­ing and un­usu­ally high tol­er­ance of prox­im­ity. (Jar­man and Bayne, 1997)

Though de­tails are un­avail­able on brush-tailed rock-wal­la­bies, most species of Macrop­o­di­dae are promis­cu­ous. Brush-tailed rock-wal­la­bies have a dif­fer­ent mat­ing sys­tem than most re­lated species in three re­spects: 1) a higher pro­por­tion of adult males are likely to take part in breed­ing and may do so for many years, 2) vari­ance in male re­pro­duc­tive suc­cess is rel­a­tively low, and 3) only some weaned fe­males, those able to es­tab­lish them­selves on a refuge, are likely to breed at all. (Jar­man and Bayne, 1997)

• Mating System
• polygynous

Fe­males are sex­u­ally ma­ture by 18 months, and males by 20 months. They breed all year, mat­ing soon after giv­ing birth. De­vel­op­ment of the em­bryo is de­layed until the pouch is va­cated. Preg­nancy lasts 31 days, after which a sin­gle young is born and at­taches to one of the 4 teats in the pouch. The young re­mains in the pouch for about 29 weeks, then suck­les at foot for about three months. In cap­tive an­i­mals, post-par­tum es­trous was typ­i­cally ob­served on the same day as birth, even some­times ap­pear­ing within a few hours. (Cronin, 2000; John­son, 1979)

The process of birth has been ob­served on one oc­ca­sion in the rock-wal­laby Pet­ro­gale peni­cil­lata in­or­nata. The fe­male sat on the base of her tail, her body lean­ing for­ward in order to bring the head close to the uro­gen­i­tal open­ing and pouch. Birth was ac­com­pa­nied by a small amount of clear fluid and blood, which the mother cleaned as the new­born young went to­ward the pouch open­ing. It took 45 sec­onds for the in­fant to reach the pouch open­ing from the uro­gen­i­tal open­ing. The mother re­mained in the birth po­si­tion for 10 more min­utes, lick­ing around the uro­gen­i­tal open­ing. (John­son, 1979)

• Key Reproductive Features
• iteroparous
• year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• viviparous
• embryonic diapause
• post-partum estrous

• Breeding interval

  The breeding interval is unknown, but females can enter estrous shortly after giving birth and breed throughout the year.

• Breeding season

  Brush-tailed rock-wallabies breed throughout the year.

• Average number of offspring

  1

• Average number of offspring

  1

  AnAge

• Average gestation period

  31 days

• Average gestation period

  30 days

  AnAge

• Average weaning age

  7 months

• Average time to independence

  7 months

• Average age at sexual or reproductive maturity (female)

  18 months

• Average age at sexual or reproductive maturity (female)
  Sex: female

  540 days

  AnAge

• Average age at sexual or reproductive maturity (male)

  20 months

• Average age at sexual or reproductive maturity (male)
  Sex: male

  590 days

  AnAge

There are few de­tails about parental in­vest­ment in Pet­ro­gale peni­cil­lata. Young re­main in the mother's pouch for around 29 weeks, where they re­ceive pro­tec­tion and milk. After leav­ing the pouch, the evicted young con­tinue to suckle for about 3 months. (Cronin, 2000)

• Parental Investment
• altricial
• female parental care
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • female

Lifes­pan/Longevity

Cap­tive brush-tailed rock-wal­la­bies have lived over 11 years. (Lav­ery and Kirk­patrick, 1985)

• Average lifespan
  Status: captivity

  11 years

• Average lifespan
  Status: captivity

  14.4 years

  Max Planck Institute for Demographic Research

Be­hav­ior

Brush-tailed rock-wal­la­bies are so­cial an­i­mals that form small colonies with dom­i­nance hi­er­ar­chies. In­di­vid­u­als have over­lap­ping home ranges with ex­clu­sive den sites. Fe­males are gre­gar­i­ous; they often share den sites with their fe­male rel­a­tives and they reg­u­larly groom each other. Rock-wal­la­bies main­tain an at­tach­ment to a pre­cisely de­fined habi­tat with a strict so­cial or­ga­ni­za­tion. One ob­served pop­u­la­tion of brush-tailed rock-wal­la­bies main­tained, dur­ing both good and bad years, an adult pop­u­la­tion of five to seven in­di­vid­u­als by vi­o­lently evict­ing young soon after wean­ing. In cap­tiv­ity, this means that weaned young may be killed if they are un­able to es­cape from the en­clo­sure. Males are rarely within 5 me­ters of an­other male. When males are in close prox­im­ity, there is al­most al­ways a vi­o­lent in­ter­ac­tion. Fe­males are more tol­er­ant of the close prox­im­ity of other fe­males than are males of other males. Fe­males do, how­ever, com­monly dis­place one an­other and en­gage in ag­o­nis­tic in­ter­ac­tions. Ad­di­tion­ally, fe­males have been seen dri­ving away fe­male and sub-adult male in­trud­ers from the vicin­ity of their refuges.

Due to the dif­fi­cul­ties of noc­tur­nal ob­ser­va­tions, much more re­mains to be learned about the be­hav­ior of brush-tailed rock-wal­la­bies. (Carter and Goldizen, 2003; Cronin, 2000; Jar­man and Bayne, 1997; Lav­ery and Kirk­patrick, 1985)

• Key Behaviors
• terricolous
• saltatorial
• nocturnal
• motile
• sedentary
• social
• dominance hierarchies

• Range territory size

  6 to 30 cm^2

• Average territory size

  15 cm^2

Home Range

Adult males have been found to have sig­nif­i­cantly larger noc­tur­nal ranges than fe­males, pos­si­bly due to their greater en­er­getic re­quire­ments or in order to in­crease their mat­ing op­por­tu­ni­ties. Range size is likely af­fected by the pro­duc­tiv­ity and nu­tri­tional value of veg­e­ta­tion at dif­fer­ent sites. High lev­els of home range over­lap are prob­a­bly due to patchy dis­tri­b­u­tions of re­sources, which leads to ag­gre­ga­tion at sources of shel­ter or food. (Laws and Goldizen, 2003)

Com­mu­ni­ca­tion and Per­cep­tion

Pet­ro­gale peni­cil­lata en­gages in al­logroom­ing, where one an­i­mal bites and licks the fur of an­other an­i­mal, which may serve a role in re­in­forc­ing dom­i­nance sta­tus. Other ex­am­ples of com­mu­nica­tive be­hav­iors in­clude mak­ing vo­cal­iza­tions (a hiss­ing cough sound), star­ing in­tensely, and ag­gres­sive be­hav­iors such as nose jab­bing (one an­i­mal thrust­ing its nose to­ward an­other an­i­mal). Males may ex­am­ine po­ten­tial fe­male mates by ap­proach­ing the fe­male and sniff­ing her rump or cloaca.

Ad­di­tion­ally, some ev­i­dence sug­gests that adult males de­posit scent marks within their area of con­trol. (Bu­lin­ski, et al., 1997; Jar­man and Bayne, 1997)

• Communication Channels
• visual
• tactile
• acoustic
• chemical

• Other Communication Modes
• scent marks

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

Pet­ro­gale peni­cil­lata feeds largely on grasses, which com­prise 35-50% of its total diet, but will sup­ple­ment its diet with leaves, sedges, ferns, roots, bark, fruit, seeds and flow­ers. Brush-tailed rock-wal­la­bies choose to for­age in lo­ca­tions with more forbs and short green grasses. There is lit­tle sea­son­al­ity of diet. Also, the rel­a­tive pro­por­tions of dif­fer­ent food types in the diet are vary lit­tle among re­gions, de­spite vary­ing veg­e­ta­tion. This sug­ests def­i­nite food pref­er­ence with lit­tle or no sea­sonal short­ages of pre­ferred foods. Since brush-tailed rock-wal­la­bies eat a wide range of food items, they are likely buffered against drought and against com­pe­ti­tion with more spe­cial­ized her­bi­vores. (Carter and Goldizen, 2003; Cronin, 2000; Short, 1989)

• Primary Diet
• herbivore
  • folivore

• Plant Foods
• leaves
• roots and tubers
• wood, bark, or stems
• seeds, grains, and nuts
• fruit

Pre­da­tion

Since brush-tailed rock-wal­la­bies ex­hibit very high fi­delity to di­ur­nally used sites, preda­tors may find it easy to learn where to find them. Fur­ther­more, be­cause colonies are small (due to de­clin­ing pop­u­la­tion size), fewer in­di­vid­u­als are avail­able to be alert in order to de­tect and warn of ap­proach­ing preda­tors. Since Pet­ro­gale peni­cil­lata has been ob­served to main­tain a rel­a­tively con­stant level of vig­i­lance re­gard­less of sur­round­ing veg­e­ta­tion, how­ever, it has been sug­gested that these an­i­mals rely on early de­tec­tion of preda­tors. Ad­di­tion­ally, brush-tailed rock-wal­la­bies are much more agile than their preda­tors. (Carter and Goldizen, 2003; Jar­man and Bayne, 1997)

• Known Predators

  • Vulpes vulpes

Ecosys­tem Roles

When they were more wide­spread, brush-tailed rock-wal­la­bies sub­stan­tially af­fected agri­cul­tural plant species. In 1880, leg­is­la­tion was passed in New South Wales de­clar­ing kan­ga­roos and wal­la­bies as ver­min. A bounty was of­fered on brush-tailed rock-wal­la­bies, sug­gest­ing that they threat­ened agri­cul­tural pro­duc­tion. They ap­par­ently in­vaded or­chards and veg­etable gar­dens with their abil­ity to jump on top of fences, and fed heav­ily on the plants there. Ad­di­tion­ally, it is pos­si­ble that brush-tailed rock-wal­la­bies help dis­perse the seeds of the fruit they eat. For in­stance, large num­bers of the seeds of Per­soo­nia lin­earis were found in the wal­la­bies' fae­cal pel­lets col­lected in the spring. (Short and Milkovits, 1990; Short, 1989)

• Ecosystem Impact
• disperses seeds

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Cap­tive pop­u­la­tions of Pet­ro­gale peni­cil­lata are the focus of be­hav­ioral, man­age­ment and ge­netic re­search. (Dovey, et al., 1997)

• Positive Impacts
• research and education

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

When brush-tailed rock-wal­la­bies were more wide­spread in Aus­tralia, they were shot as agri­cul­tural pests. They were able to enter and feed in or­chards, and veg­etable gar­dens re­quired fences sev­eral me­ters high to ex­clude them. (Short and Milkovits, 1990)

• Negative Impacts
• crop pest

Con­ser­va­tion Sta­tus

In many parts of New South Wales, Pet­ro­gale peni­cil­lata pop­u­la­tions have been re­duced to small, iso­lated colonies. Pre­da­tion, no­tably by red foxes (Vulpes vulpes), an in­tro­duced species to Aus­tralia, ap­pears to be the cur­rent major threat to Pet­ro­gale peni­cil­lata. Habi­tat degra­da­tion through veg­e­ta­tion and fire changes, com­pe­ti­tion with goats, rab­bits and sheep, and vul­ner­a­bil­ity to drought and dis­ease may also be in­volved. Brush-tailed rock-wal­la­bies have been ob­served to leave prop­er­ties where sheep were in­tro­duced, sug­gest­ing that the habi­tat-spe­cific rock-wal­la­bies were starved out by the much more ubiq­ui­tous sheep. (Bu­lin­ski, et al., 1997; Dovey, et al., 1997; Lav­ery and Kirk­patrick, 1985)

The ob­ser­va­tion of the dra­matic de­cline of a wild colony at the Jenolan caves in cen­tral New South Wales led to the first con­certed man­age­ment re­sponse to the con­tin­u­ing de­cline of Pet­ro­gale peni­cil­lata. The colony was of un­known size but sup­ple­mented by the re­lease of 88 lo­cally en­clo­sure-bred an­i­mals in 1988. Late in 1992, the re­main­ing wild an­i­mals at Jenolan were trapped and trans­ferred to a nearby en­clo­sure with the goal of es­tab­lish­ing a cap­tive breed­ing pro­gram. Such cap­tive breed­ing pro­grams gen­er­ally allow for a far greater degee of di­rect con­trol than can be ex­er­cised with wild an­i­mals. The NSW Na­tional Parks and Wildlife ser­vice (NPWS) has re­sponded to the on­go­ing de­cline of Pet­ro­gale peni­cil­lata by ini­ti­at­ing a pro­gram in­cor­po­rat­ing: 1) A sur­vey to lo­cate all sites where Pet­ro­gale peni­cil­lata> is ex­tant; 2) a com­mu­nity aware­ness and in­volve­ment cam­paign; 3) the de­vel­op­ment and im­ple­men­ta­tion of Pop­u­la­tion Man­age­ment Plans (PMPs) for ex­tant sites; 4) on-go­ing re­search into threats and im­pacts. (Bu­lin­ski, et al., 1997; Dovey, et al., 1997)

• IUCN Red List

  Near Threatened
  More information

• IUCN Red List

  Near Threatened
  More information

• US Federal List

  No special status

• CITES

  No special status

Other Com­ments

An ap­par­ently nar­row hy­brid zone has formed be­tween Pet­ro­gale peni­cil­lata and Pet­ro­gale her­berti. In this zone, at the north of Pet­ro­gale peni­cil­lata's range, some fe­male hy­brids are fer­tile, which al­lows lim­ited gene ex­change be­tween the two pop­u­la­tions. This ex­change is not wide­spread, how­ever, al­low­ing each species to re­tain its ge­netic iden­tity. (El­dridge and Close, 1995)

Con­trib­u­tors

Tanya Dewey (ed­i­tor), An­i­mal Di­ver­sity Web.

Kath­leen Bachyn­ski (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor, Phil Myers (ed­i­tor, in­struc­tor), Mu­seum of Zo­ol­ogy, Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

Bu­lin­ski, J., D. Gold­ney, J. Bauer. 1997. The habi­tat util­i­sa­tion and so­cial be­hav­iour of cap­tive rock-wal­la­bies: im­pli­ca­tions for man­age­ment. Aus­tralian Mam­mal­ogy, 19: 191-198.

Carter, K., A. Goldizen. 2003. Habi­tat choice and vig­i­lance be­hav­ior of brush-tailed rock-wal­la­bies (Pet­ro­gale peni­cil­lata) within their noc­tural for­ag­ing ranges. Wildlife Re­search, 30: 355-364.

Cronin, L. 2000. Aus­tralian Mam­mals. An­nadale, NSW: En­vi­ro­book.

Dovey, L., V. Wong, P. Bayne. 1997. An overview of the sta­tus and man­age­ment of rock-wal­la­bies (Pet­ro­gale) in New South Wales.. Aus­tralian Mam­mal­ogy, 19: 163-168.

El­dridge, M., R. Close. 1995. Brush-tailed rock-wal­laby. Pp. 383-385 in R Stra­han, ed. The Mam­mals of Aus­tralia. Chatswood, NSW: Reed Books.

Jar­man, P., P. Bayne. 1997. Be­hav­ioural ecol­ogy of Pet­ro­gale peni­cil­lata in re­la­tion to con­ser­va­tion. Aus­tralian Mam­mal­ogy, 19: 219-228.

John­son, P. 1979. Re­pro­duc­tion in the plain rock-wal­laby, Pet­ro­gale peni­cil­lata in­or­nata Gould, in cap­tiv­ity, with age es­ti­ma­tion of the pouch young. Aus­tralian Wildlife Re­search, 6: 1-4.

Lav­ery, H., T. Kirk­patrick. 1985. Kangeroos as pests. Pp. 103-132 in H Lav­ery, ed. The Kangeroo Keep­ers. St. Lucia, Queens­land: Uni­ver­sity of Queens­land Press.

Laws, R., A. Goldizen. 2003. Noc­tural home ranges and so­cial in­ter­ac­tions of the brush-tailed rock-wal­laby Pet­ro­gale peni­cil­lata at Hurlde Creek, Queens­land. Aus­tralian Mam­mal­ogy, 25: 169-176.

Short, J. 1989. The diet of the brush-tailed rock-wal­laby in New South Wales. Aus­tralian Wildlife Re­search, 16: 11-18.

Short, J., G. Milkovits. 1990. Dis­tri­b­u­tion and sta­tus of the brush-tailed rock-wal­laby in south-east­ern Aus­tralia. Aus­tralian Mam­mal­ogy, 17: 169-179.

Tag­gart, D., D. Schultz, C. White, P. White­head, G. Un­der­wood, K. Phillips. 2005. Cross-fos­ter­ing, growth, and re­pro­duc­tive stud­ies in the brush-tailed rock-wal­laby, Pet­ro­gale peni­cil­lata (Mar­su­pi­alia: Macrop­o­di­dae): ef­forts to ac­cel­er­ate breed­ing in a threat­ened mar­su­pial species. Aus­tralian Jour­nal of Zo­ol­ogy, 53: 313-323.