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).
Range mass: 0.7 to 1.8 kg.
Other Physical Features: endothermic ; bilateral symmetry
Average basal metabolic rate: 2.556 W.
Average lifespan
Status: captivity: 14.5 years.
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
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 )
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).
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).
Perception Channels: tactile ; chemical
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 of Threatened Species: least concern
Potorous tridactylus and other rat-kangaroos have been regarded by farmers as pests because of their affinity for crops (Morris 1965).
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).
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 birth mass: 0.333 g.
Average gestation period: 30 days.
Average number of offspring: 1.
Average age at sexual or reproductive maturity (female)
Sex: female: 400 days.
The long-nosed potoroo (Potorous tridactylus) is a small, hopping, gerbil-like mammal native to forests and shrubland of southeastern Australia and Tasmania. A member of the rat-kangaroo family (Potoroidae), it lives alone and digs at night for fungi, roots, or small insects. It is also a marsupial (like kangaroos) and carries its young in a pouch. The long-nosed potoroo is threatened by habitat loss and introduced species such as cats or foxes. There are two subspecies: P. t. tridactylus on mainland Australia, and P. t. apicalis on Tasmania, with lighter fur.[4]
At first glance, the long-nosed potoroo with its pointed nose and grey-brown fur looks very much like a bandicoot — that is, until it hops away with its front feet tucked into its chest, revealing its close relationship with the kangaroo family. The long-nosed potoroo exhibits many morphological specializations such as an elongated pointed rostral region (nose), erect ears, large eyes, claws for digging, and long robust hind legs.[5] It is only a small marsupial, with a body length between 34 and 38 cm (13–15 in), and a semi-prehensile tail length of 15 to 24 cm (5.9–9.4 in).[6]
As it is rarely seen in the wild, better indicators of its presence are the runways it makes through the undergrowth and the hollow diggings it leaves behind when feeding on underground roots and fungi.
The species was first noted in 1790 by John White in a record of his journey to Botany Bay. The informal description named the animal as a "Poto Roo" or "Kangaroo Rat" and was accompanied by an illustration.[7]
The classification of the genus Potorous has seen the name subjected to frequent revisions. The following is a summary of the associated species and subspecies,
The long-nosed potoroo is found in a variety of microhabitats located in the Southern Highlands of New South Wales and South-Western Victoria on the Australian mainland, and in Tasmania.[8] Its bones have been found in a number of cave deposits, indicating it was once more widespread than it is today. This species prefers a range of vegetation types, from subtropical and warm temperate rainforest, through tall open forest with dense understorey, to dense coastal heaths. Its main requirement is thick groundcover, which it needs for protection and nesting material. It also prefers light soils that are easy to dig in for the underground roots and fungi that it eats.
Home-range sizes of the long-nosed potoroo vary considerably; the largest recorded was 34.4 hectares (85 acres).[9] In Tasmania, large overlapping home ranges of 5–20 hectares (12–49 acres) have been recorded, with males typically acquiring more land than females.[9] Home ranges in Victoria, however, are much smaller.[9]
Generally, the long-nosed potoroo is solitary and has only been observed in brief encounters for mating and when with young.[5] There have also been reports of several males and females feeding in loose aggregations.[5] These mammals are non-territorial and frequently have overlapping home ranges. The male's home range can overlap many females', but the female's home range is usually exclusive,[5] allowing the female access to the male year round. Breeding, however, usually occurs from late winter to early summer.[10] Females are polyestrous and can have up to two reproductive sessions per year.[10]
The long-nosed potoroo is nocturnal, spending much of its time within the shelter of understorey vegetation. It uses long, slightly curved claws on its front feet to dig up its food. It is an omnivore and eats underground fruiting bodies of fungi, roots, fruit, flowers, seeds, and insects and their larvae.[11] Fungi are the main dietary component, and are a very important resource in the potoroo's diet, with at least 50 species consumed depending on seasonal variation.[12] During the fall and winter months, potoroos primarily consume fungi and seeds, while in the spring and summer months, the amount of arthropods, plant tissue, fruits, and flowers consumed increases.[11]
The long-nosed potoroo sniffs the ground with a side to side motion near the vicinity of food. Once the long-nosed potoroo has located a possible food source (with its sense of smell), it positions itself to begin excavating with its forepaws.[13]
Because it eats fungi, it spreads fungal spores in its droppings. Some of these fungi grow on the roots of native plants and assist the plant in the uptake of nutrients from the soil.
The long-nosed potoroo was one of the first marsupials to be described by European settlers. Unfortunately, these encounters were followed by the clearing of much of its habitat for grazing and other land uses.
Threats to the long-nosed potoroo include feral cats, wild dogs, red foxes, human settlement, and fragmentation for agriculture, livestock grazing, habitat degradation, habitat clearance/loss, and inappropriate fire regimes.[14] The pattern of burning in areas of remaining habitat has also changed, with more severe and more frequent fires creating a sparse understorey that provides little shelter for small mammals like the potoroo.
This species is listed as Near Threatened according to the IUCN red list,[2] Vulnerable in Queensland according to the Nature Conservation Act 1992 and also nationally by the Environment Protection and Biodiversity Conservation Act 1999.[14] It is listed under the Flora and Fauna Guarantee Act 1988 as endangered in Victoria.[12]
Past conservation initiatives listed the long-nosed potoroo under the Flora and Fauna Guarantee Act of 1988, construction of conservation reserves at Barren Ground Nature Reserve and Budderoo National Park, and the preparation of a recovery plan which outlines priorities for species research.[15] A completed national recovery plan is still a work in progress, however, the Department of Environment and Conservation has prepared a (PAS) Priorities Action Statement in order to help aid in the recovery of threatened species in New South Wales.[16]
This statement encourages:
There is ongoing monitoring of the long-nosed potoroo while a recovery plan is being prepared for this species.
{{cite journal}}
: Cite journal requires |journal=
(help) “Threatened Species Advanced Search." Office of Environment and Heritage. N.p., n.d. Web. 04 Dec. 2013 [1]
*(potoroo = Indigenous name for small rat-kangaroo; tridactylus = “three-toed” because it was originally believed that they only had three toes)
The long-nosed potoroo (Potorous tridactylus) is a small, hopping, gerbil-like mammal native to forests and shrubland of southeastern Australia and Tasmania. A member of the rat-kangaroo family (Potoroidae), it lives alone and digs at night for fungi, roots, or small insects. It is also a marsupial (like kangaroos) and carries its young in a pouch. The long-nosed potoroo is threatened by habitat loss and introduced species such as cats or foxes. There are two subspecies: P. t. tridactylus on mainland Australia, and P. t. apicalis on Tasmania, with lighter fur.
At first glance, the long-nosed potoroo with its pointed nose and grey-brown fur looks very much like a bandicoot — that is, until it hops away with its front feet tucked into its chest, revealing its close relationship with the kangaroo family. The long-nosed potoroo exhibits many morphological specializations such as an elongated pointed rostral region (nose), erect ears, large eyes, claws for digging, and long robust hind legs. It is only a small marsupial, with a body length between 34 and 38 cm (13–15 in), and a semi-prehensile tail length of 15 to 24 cm (5.9–9.4 in).
As it is rarely seen in the wild, better indicators of its presence are the runways it makes through the undergrowth and the hollow diggings it leaves behind when feeding on underground roots and fungi.