Potorous tridactylus (Kerr, 1792)

Russell A. Mittermeier & Don E. Wilson, 2015, Potoroidae, Handbook of the Mammals of the World – Volume 5 Monotremes and Marsupials, Barcelona: Lynx Edicions, pp. 600-628 : 628

7.

Long-nosed Potoroo

Potorous tridactylus

French: Potorou a long nez / German: Langnasen-Kaninchenkanguru / Spanish: Potoro de hocico largo

Other common names: Long-nosed Rat-kangaroo

Taxonomy. Didelphis tridactyla Kerr, 1792,

“ Botany Bay [= Sydney] , New South Wales,” Australia.

Formerly included P. gilbertii as a subspecies, but this was reinstated as a full species in 1996. Three subspecies recognized.

Subspecies and Distribution.

P.t.tnidactylusKerr,1792—patchilydistributedfromSEQueenslandSalongcoasttoGosfordregion(NofSydney),NewSouthWales;alsoFraserI,Queensland.

P.t.apicalisGould,1851—Tasmania(excludingMidlandsandAlpineregions),andalsoonBrunyI,HunterI,MariaI,RobbinsI,ThreeHummockI,andWalkerI;alsoonKingI,FlindersI,CapeBarrenI,andClarkeI(thesepopulationsmaynowbeextinct).

P.t. trisulcatus McCoy, 1865 — patchily distributed along coast from S of Sydney, New South Wales, through S Victoria (including French I; also Grampians National Park, in W Victoria) to far SE South Australia.

Descriptive notes. Head-body 25.9-41 cm, tail 18-:9-26.2 cm; weight 0-66-17 kg. Sexualsize dimorphism varies across populations with males being 0-18% larger than females. Dark brown dorsally, but varies from reddish to gray, variably grizzled with light brown to yellow; paler and more gray ventrally. Ears short and rounded. Snout long and pointed, nose and adjacent area hairless. Hindfoot shorter than head. Tail is short, sparsely furred distally, and dark; a white tip is common in southern parts of range. Diploid chromosome number is 13 for males and 12 for females.

Habitat. Rainforest, wet and dry sclerophyll forest, coastal heath, tall wet heath, and woodland. Preferred habitat has dense ground cover or understory on light, often sandy soils.

Food and Feeding. Mycophagous, feeding primarily on hypogeal (truffle-like) fungi obtained by digging with the strongly clawed forepaws. Epigeal (above-ground) fungi are also consumed. Plant material (flowers, fruits, seeds, leaves, and tubers) and invertebrates are also eaten, particularly during the drier summer months. Fungi comprise more than 50% (and up to 83%) of the diet for much of the year, but the proportion declines to 25-33% during spring and summer.

Breeding. Both males and females become sexually mature at approximately twelve months of age. Females are continuous breeders, producing one young per pregnancy and up to three young per year. Females exhibit embryonic diapause and mate shortly after having given birth. The estrous cycle is 42 days and gestation is 38 days. Following birth, the young spends 4-5 months in the pouch and is weaned at five months; after weaning it shares the mother’s squat for some months before dispersal. The mating system is thought to be promiscuous, but some instances of serial monogamy have also been recorded.

Activity patterns. Less strictly nocturnal than other potoroids. Often becomes active prior to sunset, and in some areas can also be active during the day. When resting during daylight hours, Long-nosed Potoroos use a shallow depression (“squat”) excavated under dense vegetation. They frequently use well-defined runways through dense vegetation to move about their home ranges.

Movements, Home range and Social organization. Solitary. Home range size differs with population density and habitat quality. Estimates of home ranges vary from 2 ha to 19 ha for males and from 1 ha to 5 ha for females. Home ranges showed considerable overlap both within and between the sexes, but males and females generally exhibit greater home range overlap than do individuals of the same sex. In addition, some individuals appear to be transient. Trapping and genetic studies indicate that dispersal is male-biased, subadult males dispersing (occasionally as far as 8 km) and subadult females establishing home ranges adjacent to those of their mothers.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The mainland population is listed as vulnerable in Australia. The Long-nosed Potoroo has declined significantly since European settlement, especially on the Australian mainland. Large areas of suitable habitat have been cleared for agriculture and, in coastal areas, for urban development. Many LLong-nosed Potoroo populations are now geographically isolated and fragmented, and local populations are continuing to become extinct. Populations ofthis potoroo are likely to have been reduced also through predation by introduced Red Foxes (Vulpes vulpes), domestic/feral cats (Felis catus) and feral dogs. Populations now survive only in areas of exceptionally dense vegetation that appears to offer some protection from predation. The implementation of fox-control measures at several sites in eastern Victoria has led to a significant increase in Long-nosed Potoroo numbers. Many areas of suitable habitat are now in reserves, but populations are still threatened by uncontrolled introduced predators and inappropriate fire regimes (e.g. too frequent fuel-reduction burns). In addition, large areas of remaining habitat are subject to ongoing forestry operations, which can open up the understory, making potoroos more vulnerable to predation. The Long-nosed Potoroo has remained more common in Tasmania than on the Australian mainland, with less habitat lost/fragmentation by clearing and, until recently, because of the absence of the Red Fox, but numbers are now declining as habitat loss continues, especially in the north and east. In Bass Strait, populations of this potoroid on the largest islands, King and Flinders Islands, have already declined significantly and may be extinct, as may those on Cape Barren and Clarke. The successful establishment of the Red Fox in Tasmania is likely to precipitate a major widespread decline there. A Recovery Plan has been prepared and captive populations of the two southern subspecies have been established.

Bibliography. Abbott & Burbidge (1995), Amos (1982), Andren et al. (2013), Bennett (1993), Bennett & Baxter (1989), Claridge, Tanton & Cunningham (1993), Dexter & Murray (2009), Frankham, Handasyde & Eldridge (2012), Frankham, Handasyde, Norton et al. (2014), Frankham, Reed, Eldridge & Handasyde (2012), Frankham, Reed, Fletcher & Handasyde (2011), Gould (1851), Hayman (1989), Heinsohn (1968), Hughes (1962, 1964), Johnston (2008), Johnston & Sharman (1976, 1977), Kitchener (1973), Long (2001), Martin & Temple-Smith (2010), Menkhorst & Lunney (2008), Norton, Claridge et al. (2010), Norton, French & Claridge (2010), Sarre et al. (2013), Seebeck (1981), Seebeck et al. (1989), Shaw & Rose (1979), Tory et al. (1997), Woinarski et al. (2014bp, 2014bq, 2014br, 2014bs).

Figures

1. Rufous Bettong (Aepyprymnus rufescens), 2. Burrowing Bettong (Bettongia lesueur), 3. Eastern Bettong (Bettongia gaimardi), 4. Brush-tailed Bettong (Bettongia penicillata), 5. Northern Bettong (Bettongia tropica), 6. Long-footed Potoroo (Potorous longipes), 7. Long-nosed Potoroo (Potorous tridactylus), 8. Gilbert's Potoroo (Potorous gilbertii)

Subspecies and Distribution. P.t.tnidactylusKerr,1792—patchilydistributedfromSEQueenslandSalongcoasttoGosfordregion(NofSydney),NewSouthWales;alsoFraserI,Queensland. P.t.apicalisGould,1851—Tasmania(excludingMidlandsandAlpineregions),andalsoonBrunyI,HunterI,MariaI,RobbinsI,ThreeHummockI,andWalkerI;alsoonKingI,FlindersI,CapeBarrenI,andClarkeI(thesepopulationsmaynowbeextinct). P.t. trisulcatus McCoy, 1865 — patchily distributed along coast from S of Sydney, New South Wales, through S Victoria (including French I; also Grampians National Park, in W Victoria) to far SE South Australia.