Animal Diversity Web

Ge­o­graphic Range

Po­torous tri­dacty­lus is widely dis­trib­uted in south­east­ern Aus­tralia and Tas­ma­nia and can be found in coastal New South Wales, south­east­ern Queens­land, coastal, near-coastal, and north­east­ern areas of Vic­to­ria, and the south­west­ern cor­ner of West­ern Aus­tralia (Cen­sus of Aus­tralian Ver­te­brate Species 1995 http://​www.​erin.​gov.​au/​life/​species/​fauna/​cavs81_​mammals.​html, Menkhorst 1995, Mor­ris 1965, Stra­han 1995, and Walker 1975).

• Biogeographic Regions
• australian
  • native

Habi­tat

Rel­a­tively thick ground cover is an es­sen­tial com­po­nent of a po­toroo habi­tat; there­fore, these an­i­mals in­habit forests and woods where above-ground nests of dry veg­e­ta­tion can be built among grass tus­socks, under bushes, and in low, thick shrubs (Kowal­ski 1976, Matthews 1971, Mor­ris 1965, Stra­han 1995, Walker 1975). In ad­di­tion, po­toroos uti­lize a wide va­ri­ety of wet for­est and wet scrub habi­tats de­vel­oped on sandy loam soils where an­nual rain­fall ex­ceeds 760 mm (Menkhorst 1995). Fi­nally, P. tri­dacty­lus are usu­ally found at al­ti­tudes be­tween sea level and 250 m, but they has been ob­served at al­ti­tudes up to 650 m (Menkhorst 1995).

• Terrestrial Biomes
• scrub forest

Phys­i­cal De­scrip­tion

Po­torous tri­dacty­lus is a rab­bit-sized rat-kan­ga­roo with an elon­gated muz­zle (Matthews 1971 and Mor­ris 1965). The length of its head and body is ap­prox­i­mately 300-400 mm, while its tail is about 150-260 mm long (Stra­han 1995 and Walker 1975). Its pelage is straight, soft, and loose with a grey or a light chest­nut brown col­oration of its upper parts, a gray­ish or whitish un­der­side, and often a white tipped tail (Matthews 1971, Mor­ris 1965, and Walker 1975). The me­dian claws of its manus (fore foot) - well adapted for scratch­ing and dig­ging - are very long and sharp (Hume 1982, Matthews 1971, and Mor­ris 1965). Po­torous has a down­ward-curv­ing, semi­prehen­sile tail used for car­ry­ing bun­dles of nest­ing ma­te­ri­als (Matthews 1971 and Mor­ris 1965). Its den­tal for­mula is 3/1, 1/0, 2/2, 4/4; it also has well-de­vel­oped ca­nines and bun­odont mo­lars (Mor­ris 1965 and Myers 1997). Po­toroos have en­larged hind feet and pow­er­ful hind limbs which be­stow them with adept hop­ping abil­i­ties at high speeds and a rab­bit-like gait at slower speeds (Myers 1997). Fi­nally, P. tri­dacty­lus has a well-de­vel­oped mar­supium that opens an­te­ri­orly and con­tains 4 mam­mae (teats) (Myers 1997 and Stra­han 1995). It is in­ter­est­ing to note that P. tri­dacty­lus pop­u­la­tions show con­sid­er­able mor­pho­log­i­cal vari­a­tion (Stra­han 1995). Over a dis­tance of only 200 km from the west­ern to the east­ern coast of north­ern Tas­ma­nia, the av­er­age size of these crea­tures nearly dou­bles and their coat color changes from ru­fous brown to grey-brown (Stra­han 1995). In ad­di­tion, the snout is rel­a­tively short in an­i­mals from Queens­land and in­creases pro­por­tion­ally in size in more south­ern pop­u­la­tions, being most elon­gate and nar­row in Tas­ma­nia (Stra­han 1995). Fi­nally, the pro­por­tion of in­di­vid­u­als with a white tip on their tail in­creases from zero at the north­ern ex­trem­ity of the range to 80% in Tas­ma­nia (Stra­han 1995).

Po­torous tri­dacty­lus, or the "three-toed po­toroo," is one of the first mam­mals recorded from Aus­tralia (Stra­han 1995). Its name comes from an er­ro­neous de­scrip­tion in Sur­geon-Gen­eral White's Jour­nal of a Voy­age to New South Wales in which he re­ferred to the foot of this crea­ture as hav­ing only three toes (due to the con­join­ing of its sec­ond and third dig­its) (Stra­han 1995). There­fore, the syn­dacty­lous con­di­tion found in P. tri­dacty­lus is re­spon­si­ble for the mis­nomer that has stuck with this an­i­mal ever since (Stra­han 1995).

• Other Physical Features
• endothermic
• bilateral symmetry

• Range mass

  0.7 to 1.8 kg

  1.54 to 3.96 lb

• Average basal metabolic rate

  2.556 W

  AnAge

Re­pro­duc­tion

In eu­ther­ian mam­mals the op­ti­mum tem­per­a­ture for sper­mato­ge­n­e­sis is sev­eral de­grees cooler than deep body tem­per­a­ture (Tyn­dale-Bis­coe 1973). There­fore, these mam­mals have de­vel­oped a scro­tum as an adap­ta­tion for re­mov­ing their testes from a re­gion of deep body tem­per­a­ture to one that is cooler and closer to the op­ti­mum tem­per­a­ture for sper­mato­ge­n­e­sis (Tyn­dale-Bis­coe 1973). Po­torous tri­dacty­lus is a non-eu­ther­ian mam­mal; yet, male po­toroos have adopted the above eu­ther­ian adap­ta­tion. Fe­male po­toroos are poly­oestrus such that pe­ri­ods of oestrus and prog­es­ta­tion al­ter­nate cycli­cally and pro­vide the op­por­tu­nity to con­ceive at a sec­ond or sub­se­quent oestrus if the first is in­fer­tile (Tyn­dale-Bis­coe 1973). The 42 day oestrus cycle of P. tri­dacty­lus is at the upper limit of that ob­served in mar­su­pi­als, while its ges­ta­tion pe­riod is about 38 days (Menkhorst 1995 and Tyn­dale-Bis­coe 1973).

Sex­ual ma­tu­rity among males and fe­males is reached at about 12 months, and re­pro­duc­tive po­ten­tial is about 2.5 young/year (Menkhorst 1995). Both sexes mate promis­cu­ously, and breed­ing is con­tin­u­ous through­out the year with peaks in early spring and early sum­mer (Menkhorst 1995).

Fe­males give birth to a sin­gle new­born weigh­ing nearly 300 mg . The young suck­les in the mother's mar­supium for up to 120-130 days (Menkhorst 1995 ; Tyn­dale-Bis­coe 1973). Birth is often fol­lowed by a post-par­tum oestrus; mat­ing at this time re­sults in an em­bryo which re­mains dor­mant until the ex­ist­ing young leaves the pouch nat­u­rally or dies (Menkhorst 1995). After the ex­ist­ing young va­cates the mar­supium or dies, the qui­es­cent em­bryo re­sumes de­vel­op­ment and is born ap­prox­i­mately 30 days later (Menkhorst 1995). In­ter­est­ingly, new­born off­spring of P. tri­dacty­lus and other mar­su­pi­als are much less de­vel­oped at birth than pla­cen­tal off­spring, and in fact, they re­sem­ble a human fetus after the first trimester of ges­ta­tion (Myers 1997). After the young po­toroo leaves the pouch, it will con­tinue to suckle and fi­nally be weaned after about 170 days (Menkhorst 1995).

• Key Reproductive Features
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual

• Average number of offspring

  1

  AnAge

• Average gestation period

  30 days

  AnAge

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

  400 days

  AnAge

Lifes­pan/Longevity

• Average lifespan
  Status: captivity

  14.5 years

  AnAge

Be­hav­ior

Po­torous tri­dacty­lus is noc­tur­nal and rarely ven­tures far from cover dur­ing pe­ri­ods of ac­tiv­ity (Stra­han 1995). The wide di­etary spec­trum and dig­ging habits of P. tri­dacty­lus are strong sur­vival tools (Hume 1982). These have proved in­valu­able in al­low­ing them to sur­vive after brush fires that de­stroy all avail­able food sources apart from those un­der­ground (a sit­u­a­tion that causes many other mam­mals to per­ish) (Hume 1982). Long-nosed po­toroos are seden­tary crea­tures who live rel­a­tively soli­tary ex­is­tences ex­cept dur­ing pe­ri­ods of mat­ing or when they have young at foot (Menkhorst 1995, Stra­han 1995). Male home ranges of ap­prox­i­mately 47 acres over­lap the 12.5 acre ranges of fe­males, and there is some in­di­ca­tion that the home ranges of males do not over­lap (Mac­don­ald 1984). Po­torous tri­dacty­lus may live in the wild or in cap­tiv­ity for a pe­riod of over seven years, but longevi­ties of four or five years are much more com­mon (Menkhorst 1995, Walker 1975).

• Key Behaviors
• motile

Com­mu­ni­ca­tion and Per­cep­tion

• Perception Channels
• tactile
• chemical

Food Habits

Po­torous tri­dacty­lus is an om­ni­vore and ob­tains much of its food by dig­ging shal­low holes with the claws of its fore feet (Hume 1982). Plant ma­te­r­ial - cran­ber­ries, fungi, grasses, juicy stems, roots, and tu­bers - con­sti­tute its main nu­tri­tional source through­out the year (Hume 1982, Matthews 1971, Mor­ris 1965). Of these fungi are the most com­monly eaten, while grasses are eaten only dur­ing win­ter when total food avail­abil­ity is at its low­est lev­els (Hume 1982). In­sects and their lar­vae com­pose a mea­ger 1-2% of the win­ter diet of P. tri­dacty­lus, but this can in­crease to 21% dur­ing the sum­mer when in­sect abun­dance aug­ments (Hume 1982 and Stra­han 1995). Fi­nally, it is in­ter­est­ing to note that in order to ob­tain a suf­fi­cient amount of fungi, po­toroos are forced to use a va­ri­ety of widely scat­tered feed­ing areas (Hume 1982).

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

The small num­ber and large size of P. tri­dacty­lus chro­mo­somes has led to the use of their cells - es­pe­cially those of the kid­ney and the testis - in tis­sue cul­ture stud­ies (Tyn­dale-Bis­coe 1973).

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Po­torous tri­dacty­lus and other rat-kan­ga­roos have been re­garded by farm­ers as pests be­cause of their affin­ity for crops (Mor­ris 1965).

Con­ser­va­tion Sta­tus

Po­torous tri­dacty­lus is still quite com­mon through­out Aus­tralia, al­though it and other rat-kan­ga­roos have ex­pe­ri­enced pop­u­la­tion de­creases at­trib­uted to the fol­low­ing: small size, com­pe­ti­tion with rab­bits for suc­cu­lent food, the spread­ing of poi­soned bait meant for the pop­u­la­tion con­trol of rab­bits, pre­da­tion by the in­tro­duced Eu­ro­pean fox and feral cats, and sport hunt­ing (Hume 1982, Matthews 1971, Mor­ris 1965). Most re­gional pop­u­la­tions are rel­a­tively se­cure, since the species oc­curs in con­ser­va­tion re­serves; how­ever, one iso­lated pop­u­la­tion in the Grampians re­gion of Vic­to­ria is at risk be­cause most of its very lo­cal­ized habi­tat is out­side the Na­tional Park bound­ary (Menkhorst 1995). The fre­quent oc­cur­rence of sub­fos­sil re­mains in cave de­posits in­di­cate that P. tri­dacty­lus was much more com­mon in the past (Stra­han 1995). It is not clear to what ex­tent its de­cline is the re­sult of human ac­tiv­i­ties, but it is ob­vi­ous that very large areas of suit­able habi­tat along the east­ern coast of Aus­tralia have been re­moved by land clear­ing (Stra­han 1995).

• IUCN Red List

  Least Concern
  More information

Other Com­ments

In De­cem­ber 1994 Gilbert's Po­toroo, Po­torous tri­dacty­lus gilberti, was re­dis­cov­ered at Two Peo­ples Bay Na­ture Re­serve east of Al­bany, West­ern Aus­tralia. This po­toroo was thought to be ex­tinct for 125 years prior to this dis­cov­ery, and after fur­ther in­spec­tion, three more an­i­mals were cap­tured. In total, two adult males, a sub-adult male, and two fe­males, each with a pouch young, have been cap­tured ( http://​www.​environment.​gov.​au/​life/​end_​vuln/​animals/​potoroo.​html 1997 and Stra­han 1995). Other com­mon names for P. tri­dacty­lus are the Long-nosed rat-kan­ga­roo and the Wal­laby Rat (Stra­han 1995).

Con­trib­u­tors

Nathan Lan­des­man (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

Hume, I. D. 1982. Di­ges­tive phys­i­ol­ogy and nu­tri­tion of mar­su­pi­als. Cam­bridge Uni­ver­sity Press, Cam­bridge.

Mac­don­ald, D. 1984. En­cy­clo­pe­dia of Mam­mals. Facts on File Pub­li­ca­tions, New York City.

Matthews, L. H. 1971. The Life of Mam­mals. Vol­ume Two. Uni­verse Books, New York City.

Menkhorst, P. W. 1995. Mam­mals of Vic­to­ria: Dis­tri­b­u­tion, ecol­ogy, and con­ser­va­tion. Ox­ford Uni­ver­sity Press, Mel­bourne.

Mor­ris, D. 1965. The Mam­mals: A guide to the liv­ing species. Harper & Row Pub­lish­ers, New York City.

Myers, P. 1997. An­i­mal Di­ver­sity Web. http://​www.​oit.​itd.​umich.​edu/​projects/​ADW/​

1995. Cen­sus of Aus­tralian Ver­te­brate Species Web­page. http://​www.​erin.​gov.​au/​life/​species/​fauna/​cavs81_​mammals.​html

1997. http://​www.​environment.​gov.​au/​life/​end_​vuln/​animals/​potoroo.​html

Stra­han, R. 1995. Mam­mals of Aus­tralia. Smith­son­ian In­sti­tu­tion Press, Wash­ing­ton, D.C.

Tyn­dale-Bis­coe, H. 1973. Life of Mar­su­pi­als. Amer­i­can El­se­vier Pub­lish­ing Com­pany, Inc., New York City.

Walker, E. P. 1975. Mam­mals of the World. Third Edi­tion. Vol­ume One. The Johns Hop­kins Uni­ver­sity Press, Bal­ti­more.