Southern Hairy-nosed Wombat

Southern Hairy-nosed Wombat[1]
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Infraclass: Marsupialia
Order: Diprotodontia
Family: Vombatidae
Genus: Lasiorhinus
Species: L. latifrons
Binomial name
Lasiorhinus latifrons
(Owen, 1845)
Southern Hairy-nosed Wombat range

The Southern Hairy-nosed Wombat (Lasiorhinus latifrons) is one of three species of wombats. It is found in scattered areas of semi-arid scrub and mallee from the eastern Nullarbor Plain to the New South Wales border area. It is the smallest of all three wombat species. The young often do not survive dry seasons. It is the state animal of South Australia.[3]

The oldest southern hairy-nosed wombats ever documented were a male and a female from Brookfield Zoo just outside of Chicago. Their names were Carver, who lived to be 34, and his mother, Vicky, who lived to be 24.

Contents

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Physical description

The southern hairy-nosed wombat has a stocky and robust build adapted for digging. It is plantigrade and digs with its flattened claws found on each of its 5 digits.[4] The body length ranges 772–934 mm (30.39-36.77 in) with a body mass ranging 19–32 kg (41.8-70.4 lbs).[4] It has a short tail that is hidden by its fur. The pelage is silky and ranges in colour from grey to tan. The second and third toes of the wombat’s hind feet are mostly conjoined, apart from their terminal joints, forming a digit with two claws which the wombat uses for grooming.[5][6] The head is robust and flattened with extended, pointed ears.[7] The snout is pig-like.[5] The animal gets its name from the soft fur covering its rhinarium.[4] The wombat's incisors resemble those of rodents and have molars with a wide palate between them.[5] All the teeth grow continuously throughout its life, which is likely an adaptation to its harsh diet.[4] Compared to the common wombat, the southern hairy-nosed wombat has a better developed temporalis muscle and a more reduced masseter muscle.[8] It is also distinguished from the northern hairy-nosed wombat, with its nasal bone being longer than the frontal bone.[4]

Biology and ecology

Southern hairy-nosed wombats live in Western Australia, southern South Australia, and south-western New South Wales. They inhabit semi-arid to arid grasslands and woodlands that receive 200 to 500 mm of rain per year.[7]

Feeding and energy

Southern hairy-nosed wombats, along with other wombat species, prefer to eat tough native perennial grasses and sedges when given the choice.[9] However, they will eat introduced pasture species, as well as forbs and the leaves of woody shrubs when in adverse conditions.[5] Much of the southern hairy-nosed wombat's diet is Stipa nitida, which grows around its warren complex and becomes close cropped as the wombat grazes nearby.[9] This creates an area with a higher density of new green shoots, a sign of delayed growth of individual grass can break down when grazing on the same plant species.[5] The teeth of the wombat can grind food to a mean particle size half that of what a Western grey kangaroo grazing on the same species.[5] The digestive tract of the wombat has a tiny caecum and a colon with two clearly defined parts.[9] The anterior part is larger and acts as the main fermentation chamber and the posterior part is where water is reabsorbed. For the southern hairy-nosed wombat, the fermentation chamber is comparatively small and the posterior part is large, an adoption for its desert environment.[9] The wombat conserves water by recycling more urea to the colon rather than excreting it as urine. Wombats have the lowest recorded water turnovers for herbivorous mammals.[10] As such the southern hairy-nosed wombat produces very dry faeces with water content as low as 40%.[9]

The harsh environment in which the southern hairy-nosed wombat lives is further reflected in its energetics. The standard metabolic rate (SMR) was measured in captivity to be 130 kl/kg^0.75 per day which is very low, being only 64% of the marsupial average or 42% of the placental mammal average.[10][11] The thyroid hormone levels, which are a reflection of SMR, are the lowest recorded for any mammal.[9] It has been calculated that the amount of forage consumed provides 2.8 times the maintenance energy needs of the wombat, which is very similar to the radio between SMR and field metabolic rates (FMR) for the koala, greater glider and for the common ringtail possum during late lactation.[10] As such, as long as there’s enough food, its preferred diet is sufficient to support the lactation of the animal. The nitrogen, water and energy needs of the wombat are very frugal and thus it is able to maintain its body mass on food of very low quality, even during droughts.[10] It can outperform a donkey which has a lower metabolic rate, lower food intake and slower rate of passage.[12]

Burrow system and activities

Southern hairy-nosed wombats dig and live in burrow which they connect into warrens with many interconnected entrances. These warrens are their prime refuges and are shared by up to ten individuals.[9] When digging a burrow, a wombat sits on its hind end and uses its forepaws to dig at the earth and pushes it to the side.[13] When the wombat leaves its new burrow, it exits backward, pushing the dirt out with all four of its paws.[13] The central warren is surrounded by a circle of small simple burrows 100–15 m from it.[11] Resident wombats graze as far as the perimeter burrow which also provide a temporary refuge to extend the grazing area further. They also provide a temporary refuge for young wombats that have been driven from the central warren.[9] Wombats do not share burrows within a warren. While they show some preference for particular burrows and warrens, with females showing a greater tendency to stay near a burrow system than males do, there are no individual claims of ownership of a particular burrow.[14] Wombats will change burrows and even warrens. There appears to be some separation of sectors of the common grazing area between members of the group in the warren.[9] Male wombats are territorial towards other warren groups, possibly to defend food resources and the warren refuges.[9] Trails of droppings connect the burrows together and serve to mark the territory. They also mark their territory with scent secretions from their anal scent glands by rubbing their backs and rumps on objects and.[5] Occasionally, two males may fight to defend their territories or mates, biting the ears, flank, or rump.[4] There is also a dominance hierarchy among males.[4]

The burrows of a southern hairy-nosed wombat can have air temperatures within the range of 14°C in mid winter to 26°C in mid summer, the preferred thermo-neutral zone of the wombat, while the air temperatures on the surface are around 2°C to 36°C.[15] Warrens can make surface conditions in habitats of low humidity and high temperatures better for the wombat.[15] When a wombat forages outside and then returns, it retreats into the depths of the burrow.[11] When it is about to emerge the following night it moves towards to the burrowing entrance but retreats if the temperatures is too high or the humidity is too low.[11] In the evening, wombats emerge from their burrows as the outside temperature is the same as the burrow temperature. In the early morning, they return as the ambient temperature is still below the burrow entrance.[16] They use the burrow complex to avoid the outside climate extremes and conserve water and energy by remaining within their thermo-neutral zone at all times.[9]

Mating and reproduction

The breeding of the southern hairy-nosed wombat occurs when their favoured food is at their highest growth rates. The reproduction of wombats is affected by the amount of winter rainfall, being dependent on the germination of grasses.[5] Between August and October, when there is enough rainfall, females ovulate and males have high testosterone levels and enlarged prostate glands. In years of low rainfall, females do not ovulate and the testosterone level of males is low their prostate glands are small.[9] During the breeding season, dominance hierarchies among males are maintained though aggression.[6] Copulation takes place in the warren with males remaining in one burrow and females moving among them. During copulation the male turns the female on her side and mounts her from behind, this lengthens the time of intro-mission.[14] The gestation period of the wombat lasts 22 days and most births occur in October. When a young is born, it attaches to one of the two teats in the pouch. A young remains in the pouch for six months At this time, it is lightly furred with its eyes open and it weighing about 0.45 kg.[9] It leaves the pouch prematurity about three months later, in July or August, and makes its first emergence out of the burrow and feeds on grass. It is not fully weaned until it is one year old and doesn’t reach full size until it is three years old.[9] When a young is weaned, the mother can reproduce again.[4]

Communication

Southern hairy-nosed wombats use vocalisations and scents for communication. Wombats rely more heavily on scent to communicate as direct encounter between them are rare.[4] Wombats will investigate scents recently left by other wombats.[11] While most communication between wombats occurs through olfaction and scent marking, wombats will emit rough coughing noises when they pass each other[11] and will emit a more strident call to alert others when alarmed.[5]

Status

The southern hairy wombat is listed as Least Concern by the IUCN because "While there are sporadic outbreaks of sarcoptic mange, competition with introduced herbivores, susceptibility to drought, and severe fragmentation in parts of its range, the species has a wide distribution, large population, occurs in a number of protected areas, and it is unlikely to be declining at nearly the rate required to qualify for listing in a threatened category".[2] Wombats were hunted by aboriginal people for their meat. However, capturing a wombat takes a lot of time and energy and so they were not hunted too frequently.[17] The indigenous people of Australia value the wombat culturally and keep their own wombat populations healthy by hunting wombats elsewhere.[17]

Wombats can be agricultural pests. They can destroy crops when they dig their burrows and livestock may break their legs when they break through into a wombat burrow.[18] Livestock and rabbits compete with wombats for forage and this can lead to overgrazing. Overgrazing leads to annual grass species becoming the dominant species and wombats can't get all of their metabolic needs from these.[4] Currently the spread of rabbits throughout Australia is one of the main threats to their survival.[4]

Populations

This species is has a patchy distribution across its range. On the Nullarbor Plain, it is abundant with estimates of between 50,000 and 100,000 in the South Australian portion but no population estimates for Western Australia. 10,000-15,000 wombats appear to inhabit the Murray Lands, but drought and sarcoptic mange likely caused the population to decline by 70% here since 2002.[2] In the Yorke and Eyre Peninsulas the population is highly fragmented.

References

  1. ^ Groves, Colin P. (16 November 2005). "Order Diprotodontia (pp. 43-70)". In Wilson, Don E., and Reeder, DeeAnn M., eds. Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Baltimore: Johns Hopkins University Press, 2 vols. (2142 pp.). pp. 43-44. ISBN 978-0-8018-8221-0. OCLC 62265494. http://www.bucknell.edu/msw3/browse.asp?id=11000012. 
  2. ^ a b c Taggart, D. & Robinson, T. (2008). Lasiorhinus latifrons. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 28 December 2008. Database entry includes justification for why this species is of least concern
  3. ^ http://australian-animals.net/wombat-s.htm
  4. ^ a b c d e f g h i j k Lasiorhinus latifrons southern hairy-nosed wombat Animal Diversity
  5. ^ a b c d e f g h i Wells, R. 1989. Vombatidae, Pp. 1-25 in D. W. Walton, ed. Fauna of Australia. Canberra, Australia: Australian Government Publishing Service.
  6. ^ a b Cronin, L. 2000. Australian Mammals. Annandale: Envirobook.
  7. ^ a b Menkhorst, P. 2001. A Field Guide to the Mammals of Australia. South Melbourne: Oxford University Press.
  8. ^ Nakajima, K., G. Townsend. 1994. "A morphometric study of the skulls of two species of wombats (Vombatus ursinus and Lasiorhinus latifrons)". Australian Mammalogy, 17: 65-72.
  9. ^ a b c d e f g h i j k l m n H Tyndale-Biscoe. 2005. Life of Marsupials. pp. 269-85. CSIRO Publishing.
  10. ^ a b c d Wells RT, Green B 1998. "Aspects of water metabolism in the southern hairy-nosed wombat Lasiorhinus latifrons". In: Wells. RT, Pridmore PA (eds) Wombats. Surrey Beatty, Chipping Norton.
  11. ^ a b c d e f R. T. Wells. 1978. "Thermoregulation and activity rhythms in the hairly-nosed wombats, Laisorhinus latifrons (Owen), (Vombatidae) ". Australian Journal of Zoology 26 (4): 639–51.
  12. ^ Hume ID (1999) Marsupial Nutrition. p. 434. Cambridge: Cambridge University Press.
  13. ^ a b Ride, W. 1970. A Guide to the Native Mammals of Australia. Melbourne: Oxford University Press.
  14. ^ a b Wells, R. 1995. "Southern Hairy-nosed Wombat Lasiorhinus latifrons (Owen, 1845)". Pp. 202-203 in R. Strahan, ed. Mammals of Australia. Chatswood, N.S.W.: Reed Books.
  15. ^ a b Shimmin GA, Skinner J, Baudinette RV. 2002. "The warren architecture and environment of the southern hairy-nosed wombat (Lasiorhinus latifrons) ". Journal of Zoology 258: 469-77.
  16. ^ Tayor GK. 1998. "A long tern population study of the southern hairy-nosed wombat Laisorhinus latifrons at Moorude Wildlife Reserve, South Australia". In Wells. RT, Pridmore PA (eds) Wombats. Surrey Beatty, Chipping Norton. p. 198-205.
  17. ^ a b Davies J. 1998. "Who Owns the Animals? Sustainable Commercial use of Wildlife and Indigenous Rights in Australia" Presented at "Crossing Boundaries" the seventh annual conference of the International Association for the Study of Common Property, Vancouver, British Columbia, Canada, 10–14 June 1998.
  18. ^ Nowak, R. 1991. Walker's Mammals of the World. Baltimore, Maryland: Johns Hopkins University Press.