Greater glider

Greater glider[1]
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Infraclass: Marsupialia
Order: Diprotodontia
Family: Pseudocheiridae
Subfamily: Hemibelideinae
Genus: Petauroides
Thomas, 1888
Species: P. volans
Binomial name
Petauroides volans
(Kerr, 1792)
Greater glider range
Synonyms

Schoinobates volans

The greater glider (Petauroides volans) is a small gliding marsupial found in Australia. It is not closely related to the Petaurus group of gliding marsupials but instead to the lemur-like ringtail possum (Hemibelideus lemuroides), with which it shares the subfamily Hemibelideinae.[1]

The greater glider is nocturnal and is a solitary herbivore feeding almost exclusively on Eucalyptus leaves and buds.[3] Like its relative the lemur-like ringtail, the greater glider is found in two forms: a sooty brown form, or a grey-to-white form.[3]

The greater glider is found in eucalypt forest from Mossman, Queensland, to Daylesford, Victoria.[3]

Anatomy and physiology

Skeleton

Greater gliders have a head and body about 39 to 43 centimetres (15 to 17 in) long, with the females being generally larger than the males. Their body is covered with a shaggy coat of fur that increases their apparent size, and the tail is long and bushy, ranging from 44 to 53 centimetres (17 to 21 in). The head is short, but with a pointed muzzle, and large ears fringed and backed with long fur. Each side of the body bears membranes stretching between the elbow and the ankle, that give the animal the ability to perform controlled glides. This is in contrast to other gliding marsupials (such as the sugar glider) that have gliding membranes stretching from the wrists to the ankles.[4]

The feet have strongly recurved claws to grip onto bark or other surfaces. There are five toes on each foot, with the first toe on the hind foot, and the first two toes on the fore foot, being opposable.[4]

The fur is soft and up to 60 millimetres (2.4 in) long; the colour is variable within the same populations, ranging from white to brown and charcoal. Body mass varies clinally from about 1,600 grams (3.5 lb) in southern Victoria to about 600 grams (1.3 lb) in north Queensland.

Physiology

Heat management in the greater glider is performed by licking extremities and the ventral body surface, with direct evaporation being the main method of the cooling. Furthermore, the glider can use its gliding membranes to reduce heat loss by increasing the layer of insulation at the skin surface. However, the greater glider is not well equipped to handle high ambient temperatures, as it inefficiently uses water for evaporation via salivation even though arboreal habitats are often limited in water accessibility.[5]

The greater glider can digest low nutrient foliage, specifically eucalypt leaf matter, which contains a variety of phenolic and terpenoid compounds and a high concentration of lignified fibre. Animals can digest about 50–60% of the leaf during its passage through the gut [6] The gut has a specialized caecum that is contains a population of bacteria that ferment food residues that remain undigested in the small intestine.[7] For a population in a eucalypt forest near Maryborough, Queensland, it has been calculated that their daily energy intake is about 1130 kJ, which is provided by about 45 to 50 grams (0.099 to 0.110 lb) of dry matter daily.[8]

Mature females will give birth to a single progeny, each year which is typically born in late autumn or early winter. The underdeveloped offspring will then spend the next four months within the pouch of the mother to suckle and develop. It will remain within the security of the pouch until about nine months of age.[9]

Distribution and habitat

The greater glider is found in southern Queensland,[10] eastern Australia,[11] southeastern New South Wales,[12] and the montane forests of the Victorian central highlands.[13] The greater glider is usually tracked via spotlighting on transects (considered to underestimate the actual population size), radio tagging and owl-call playback.[14][15]

There are two recognised subspecies:[1]

The greater glider chooses habitat based on several factors. A large factor determining habitat choice is the presence of specific species of eucalypt. Distribution levels are higher in regions of montane forest containing manna gum (E. viminalis) and mountain gum (E. dalrympleana, E. obliqua). Furthermore, the presence of E. cypellocarpa appears to improve the quality of habitat for the greater glider in forests dominated by E. obliqua. Another factor determining population density is elevation. Optimal levels are 845 m above sea level.[16] Within a forest of suitable habitat, they prefer overstorey basal areas in old-growth tree stands.[14]

Behaviour

Head of a dark morph of the greater glider

The greater glider is primarily nocturnal, spending the night foraging in the highest parts of the forest canopy. During the day, it spends most of its time denning in hollowed trees, with each animal using up to twenty different dens within its home range. The dens are often lined with leaves and strips of bark.[4][17] This is why spotlighting has become a popular way of locating members of a population; when a strong light is directed at the eyes of a glider, the observer will see two bright red orbs reflecting back.[15]

Within forests, males and females will have home territories and set borders between other members. For males, home territory ranges from 1.4 to 4.1 hectares (3.5 to 10.1 acres) while that of females is only 1.3 to 3.0 hectares (3.2 to 7.4 acres). Although home ranges may overlap, the animals remain generally solitary outside of the breeding season, and only rarely interact. In large and small patches of forest, the home territories will respectively be larger and smaller.[18]

The gliding posture of the greater glider is unique among marsupials. The forelimbs are folded so that the wrists are tucked under the chin, giving the patagium a triangular outline when outstretched. The animal regularly glides between high trees, and is able to use the tail to assist in steering. They avoid travelling along the ground whenever possible, and are slow and clumsy if forced to do so.[4]

Greater gliders do not make any loud sounds,[19] and probably communicate through scent marking. The animal's cloacal glands give it a generally musty smell.[20][21]

Ecology

Greater glider at Kioloa

Greater gliders subsist almost entirely on the young leaves and flower buds of select eucalypt species, especially Eucalyptus radiata, Eucalyptus viminalis, and Eucalyptus acmenoides.[20] Young leaves are preferred because they have higher concentration of nitrogen and lower concentration of lignocellulose (acid-detergent fibre). Overall, the eucalypt leaves are a poor source of nutrients.[22]

Because of its night time activities, a natural predator on the glider is the powerful owl (Ninox strenua). It hunts by concentrating in pockets within their relatively large home range until populations of prey are depleted to a level that causes the owl to shift hunting grounds.[23] Other predators include feral cats, which are not native to Australia, being introduced with the arrival of Europeans.[24]

Reproduction

The breeding season for greater glider is relatively brief, lasting from February to May, with births occurring between April and June. Females have a relatively well-developed pouch, opening towards the forward part of the animal, and containing two teats.[4] Only a single young is born each year.[3]

At birth, the young weighs only around 0.27 grams (0.0095 oz), but it does not begin to leave the pouch for about four months, by which time it is already furred and well developed. After leaving the pouch, the mother may carry it about on her back, until it is weaned at about seven months of age. The young are independent at nine months, and reach sexual maturity between 18 months and two years after birth.[4]

Greater gliders have been recorded as living for up to fifteen years.[25]

Evolution

Although previously thought to be related to the other gliding possums, the greater glider is now known to be most closely related to the ringtail possums, and especially to the lemur-like ringtail possum, from which its ancestors diverged around 18 million years ago. In contrast, it diverged from the gliding possums much earlier, around 36 million years ago.[26] Fossils of greater gliders are known from the late Pleistocene onwards, and show that the animal was once more widespread, also being found in at least some areas of South Australia.[4]

References

  1. 1 2 3 Groves, C.P. (2005). Wilson, D.E.; Reeder, D.M., eds. Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Baltimore: Johns Hopkins University Press. p. 51. OCLC 62265494. ISBN 0-801-88221-4.
  2. ↑ Lunney, D., Menkhorst, P., Winter, J., Ellis, M., Strahan, R., Oakwood, M., Burnett, S., Denny, M. & Martin, R. (2008). Petauroides volans. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 28 December 2008.
  3. 1 2 3 4 Menkhorst, Peter (2001). A Field Guide to the Mammals of Australia. Oxford University Press. p. 94. ISBN 0-19-550870-X.
  4. 1 2 3 4 5 6 7 Harris, J.M. & Maloney, K.S. (2010). "Petauroides volans (Diprotodontia: Pseudocheiridae)". Mammalian Species 42 (1): 207–219. doi:10.1644/866.1.
  5. ↑ Rubsamen, K.; Hume, I.D.; Foley, W. J.; Rubsamen, U. (1984). "Implications of the large surface area to body mass ratio on the heat balance of the Greater Glider Petauroides volans". Journal of Comparative Physiology B: Biochemical Systemic and Environmental Physiology 154 (1): 105–111. doi:10.1007/BF00683223.
  6. ↑ Foley, W. J.; Lassak, E. V.; Brophy, J. (1987). "Digestion and absorption of eucalyptus essential oils in the Greater Glider Petauroides volans and Brushtail Possum Trichosurus vulpecula". Journal of Chemical Ecology 13 (11): 2115–2130. doi:10.1007/BF01012875.
  7. ↑ Foley, W. J.; Hume, I. D.; Cork, S. J. (1989). "Fermentation in the hindgut of the Greater Glider Petauroides volans and the Brushtail Possum Trichosurus vulpecula, two arboreal folivores". Physiological Zoology 62 (5): 1126–1143.
  8. ↑ Foley, W. J.; Kehl, J.C.; Nagy, K.A.; Kaplan, I.R.; Boorsboom, A.C. (1990). "Energy and Water Metabolism in Free-living Greater Gliders Petauroides volans". Australian Journal of Zoology 38 (1): 1–10. doi:10.1071/ZO9900001.
  9. ↑ "Greater Glider Petauroides volans in the Eurobodalla Local Government area - proposed endangered population listing". New South Wales Department of Environment and Climate Change. Retrieved 2008-05-05.
  10. ↑ Wormington, K. R.; Lamb, D.; McCallum, H. I.; Moloney, D. J. (2002). "Habitat requirements for the conservation of arboreal marsupials in dry sclerophyll forests of southeast Queensland, Australia". Forest Science 48 (2): 217–227.
  11. ↑ Taylor, A. C.; Kraiaijeveld, K.; Lindenmayer, D. B. (2002). "Microsatellites for the greater glider, Petauroides volans". Molecular Ecology Notes 2 (1): 57–59. doi:10.1046/j.1471-8286.2002.00148.x.
  12. ↑ Viggers, K. L.; Lindenmayer, D. B. (2001). "Haematological and plasma biochemical values of the greater glider". Australian Journal of Wildlife Diseases 37 (2): 370–374. doi:10.7589/0090-3558-37.2.370.
  13. ↑ Incoll, R. D.; Loyn, R. H. (2001). Ward, S. J.; Cunningham, R. B.; Donnelly, C. F.. "The occurrence of gliding possums in old-growth forest patches of mountain ash (Eucalyptus regnans) in the Central Highlands of Victoria". Biological Conservation 98 (1): 77–88. doi:10.1016/S0006-3207(00)00144-0.
  14. 1 2 Incoll, R. D.; Loyn, R. H.; Ward, S. J.; Cunningham, R. B.; Donnelly, C. F. (2001). "The occurrence of gliding possums in old-growth forest patches of mountain ash (Eucalyptus regnans) in the Central Highlands of Victoria". Biological Conservation 98 (1): 77–88. doi:10.1016/S0006-3207(00)00144-0.
  15. 1 2 Lindenmayer, D. B.; Cunningham, R. B.; Donnelly, C. F.; Incoll, R. D.; Pope, M. L.; Tribolet, C. R.; Viggers, K. L.; Welsh, A. H. (2001). "How effective is spotlighting for detecting the greater glider (Petauroides volans)?". Wildlife Research 28 (1): 105–109. doi:10.1071/WR00002.
  16. ↑ Kavanagh, Rodney P. (2000). "Effects of variable-intensity logging and the influence of habitat variables on the distribution of the Greater Glider Peaturoides volans in montane forest, southeastern New South Wales". Pacific Conservation Biology 6 (1): 18–30.
  17. ↑ Smith, G.C.; et al. (2007). "Home range and habitat use of a low-density population of greater gliders, Petauroides volans (Pseudocheiridae: Marsupialia), in a hollow-limiting environment". Wildlife Research 34 (6): 472–483. doi:10.1071/WR06063.
  18. ↑ Pope, M. L.; Lindenmayer, D. B.; Cunningham, R. B. (2004). "Patch use by the greater glider (Petauroides volans) in a fragmented forest ecosystem. I. Home range size and movements". Wildlife Research 31 (6): 559–568. doi:10.1071/WR02110.
  19. ↑ Borsboom, A. (1982). "Agonistic interactions between bats and arboreal marsupials". Australian Mammalogy 5: 281–282.
  20. 1 2 Comport, S. S.; Ward, S. J.; Foley, W. J. (1996). "Home ranges, time budgets and food-tree use in a high-density tropical population of greater gliders, Petauroides volans minor (Pseudocheiridae: Marsupialia)" (PDF). Wildlife Research 23 (4): 409–419. doi:10.1071/WR9960401.
  21. ↑ Pockets Pets Team. "Pocket Pets". GRE, Inc. Retrieved 6 November 2012.
  22. ↑ Kavanagh, R. P.; Lambert, M. J. (1990). "Food selection by the Greater Glider Petauroides volans: is foliar nitrogen a determinant of habitat quality?". Australian Wildlife Research 17 (3): 285–300. doi:10.1071/WR9900285.
  23. ↑ Kavanagh, R. P. (1988). "The impact of predation by the Powerful Owl Ninox strenua on a population of the Greater Glider Petauroides volans". Australian Journal of Ecology 13 (4): 445–450. doi:10.1111/j.1442-9993.1988.tb00992.x.
  24. ↑ "Greater Glider". Gliders in the Spotlight. Wildlife Preservation Society of Queensland. Retrieved 2008-05-05.
  25. ↑ Lindenmeyer, D.B. (1997). "Differences in the biology and ecology of arboreal marsupials in forests of southeastern Australia". Journal of Mammalogy 78 (4): 1117–1127. doi:10.2307/1383054. JSTOR 1383054.
  26. ↑ Springer, M.S.; et al. (1992). "Relations among ringtail possums (Marsupialia, Pseudocheiridae) based on DNA–DNA hybridization". Australian Journal of Zoology 40 (4): 423–435. doi:10.1071/ZO9920423.

Bibliography

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