Greater Glider

Taxobox
name = Greater GliderMSW3 Groves|pages=51]


status = LC
status_system = iucn3.1
status_ref = IUCN2006|assessors=Australasian Marsupial & Monotreme Specialist Group|year=1996|id=40579|title=Petauroides volans|downloaded=26 December 2006]
regnum = Animalia
phylum = Chordata
classis = Mammalia
infraclassis = Marsupialia
ordo = Diprotodontia
familia = Pseudocheiridae
subfamilia = Hemibelideinae
genus = "Petauroides"
genus_authority = Thomas, 1888
species = "P. volans"
binomial = "Petauroides volans"
binomial_authority = (Kerr, 1792)

The Greater Glider ("Petauroides volans") is a large gliding possum found in Australia. It is not, in fact, closely related to the lesser gliding possums but instead to the Lemur-like Ringtail Possum ("Hemibelideus lemuroides"), with which it shares the subfamily Hemibelideinae.

The Greater Glider is roughly the size of a domestic cat and is a nocturnal and solitary herbivore feeding mostly on "Eucalyptus" leaves and buds.cite book | last = Menkhorst | first = Peter | year = 2001 | title = A Field Guide to the Mammals of Australia | publisher = Oxford University Press | pages = 94] 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.

The Greater Glider is found in wet sclerophyll forest from Mossman, Queensland, to Daylesford, Victoria. A single young is born after mating (which occurs from March to June), which leaves the pouch at four months of age, and is independent at nine months.

Anatomy and physiology

The body size is similar to that of a House Cat, and it possess a long tail, approximately 500mm long, to assist with travel in the understory. It possesses the phenotypes for various colours within the same populations, ranging from white to brown and charcoal. Body mass can vary, but it is usually around 1kg. Reasons for variability are due to population density and nutrient availability. For a population in a eucalypt forest near Maryborough, Queensland, it has been calculated that their daily energy intake is about 1130 kJ, which translates to the need to eat 45 to 50 g of dry matter daily. [Cite journal|last=Foley|first=W. J.|coauthors=Kehl, J.C.; Nagy, K.A.; Kaplan, I.R.; Boorsboom, A.C.|title=Energy and Water Metabolism in Free-living Greater Gliders "Petauroides volans"|journal=Australian Journal of Zoology|volume=38(1)|year=1990|pages=1-10]

The Greater Glider has the ability to perform controlled glides. This is made possible by membranes which stretch between the legs. These flaps do not allow positive lift however, as seen in bats.

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. [cite journal|last=Rubsamen|first=K.|coauthors=Hume, I.D.; Foley, W. J.; Rubsamen, U.|title=Implications of the large surface area to body mass ratio on the heat balance of the Greater Glider "Petauroides volans"|journal=Journal of Comparative Physiology B: Biochemical Systemic and Environmental Physiology|volume=154(1)|year=1984|pages=105-111]

The Greater Glider has also evolved the ability to digest low nutrient foliage, specifically eucalypt leaf matter, which contains toxic oils and high ligand content. Studies have shown that approximately 96-97% of the gut is able to digest oils. [cite journal|last=Foley|first=W. J.|coauthors= Lassak, E. V.; Brophy, J.|title=Digestion and absorption of eucalyptus essential oils in the Greater Glider "Petauroides volans" and Brushtail Possum "Trichosurus vulpecula"|journal=Journal of Chemical Ecology|volume=13(11)|year=1987|pages=2115-2130] The gut has a specialized caecum and proximal colon that are equipped to hold microbial activity, which is essential for the breakdown of foliage via fermentation. The caecum is respectively longer than that of humans so that more plant matter can be broken down. [cite journal|last=Foley|first=W. J.|coauthors=Hume, I. D.; Cork, S. J.|title=Fermentation in the hindgut of the Greater Glider "Petauroides volans" and the Brushtail Possum "Trichosurus vulpecula", two arboreal folivores|journal=Physiological Zoology|volume=62(5)|year=1989|pages=1126-1143]

Reproductive processes are similar to that of many other marsupials. Mature females will annually give birth to a single progeny, which is typically born in late autumn or early winter. The underdeveloped offspring will then spend the next 4 months within the pouch of the mother to suckle and develop. It will remain within the security of the pouch until about 9 months of age. [cite web|title=Greater Glider "Petauroides volans" in the Eurobodalla Local Government area - proposed endangered population listing|url=http://www.environment.nsw.gov.au/determinations/PetaroidesVolansEndangeredPopulationPreliminary.htm|publisher=New South Wales Department of Environment and Climate Change|accessdate=2008-05-05]

Behaviour and ecology

Dietary preferences of the Greater Glider is restricted to the young leaves and flower buds of select eucalypt species, specifically "Eucalyptus acmenoides". [cite journal|last=Comport|first=S. S.|coauthors=Ward, S. J.|Foley, W. J.|title=Home ranges, time budgets and food-tree use in a high-density tropical population of greater gliders, "Petauroides voalans minor" (Pseudocheiridae: Marspupialia|journal=Wildlife Research|volume=23(4)|pages=409-419|year=1996] 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. [cite journal|last=Kavanagh|first=R. P.|coauthors=Lambert, M. J.|title=Food selection by the Greater Glider "Petauroides volans": is foliar nitrogen a determinant of habitat quality?|journal=Australian Wildlife Research|volume=17(3)|year=1990|pages=285-300]

The Greater Glider chooses habitat based on several factors. A larger determining factor habitat choice is the presence of specific species of eucalypt. Distribution levels were found to be higher in forest regions of montane forest, an area in southeastern New South Wales, 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", based on prior studies. Another factor to determine population density is elevation. Optimal levels were found to be 845 m above sea level. [cite journal|last=Kavanagh|first=Rodney P.|title=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|journal=Pacific Conservation Biology|volume=6(1)|year=2000|pages=18-30] Within a forest of suitable habitat, they prefer overstorey basal areas in old-growth tree stands.cite journal|last=Incoll|first=R. D.|coauthors=Loyn, R. H.; Ward, S. J.; Cunningham, R. B.; Donnelly, C. F.|title=The occurrence of gliding possums in old-growth forest patches of mountain ash ("Eucalyptus regnans") in the Central Highlands of Victoria|journal=Biological Conservation|volume=98(1)|year=2001|pages=77-88]

The Greater Glider is primarily nocturnal, spending the twilight hours foraging. During the day, it spends most of its time in a lowered energy state within hollowed trees. 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. cite journal|last=Lindenmayer|first=D. B.|coauthors=Cunningham, R. B.; Donnelly, C. F.; Incoll, R. D.; Pope, M. L.; Tribolet, C. R.; Viggers, K. L.; Welsh, A. H.|title=How effective is spotlighting for detecting the greater glider ("Petauroides volans")?|journal=Wildlife Research|volume=28(1)|year=2001|pages=105-109] 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. [cite journal|last=Kavanagh|first=R. P.|title=The impact of predation by the Powerful Owl "Ninox strenua" on a population of the Greater Glider "Petauroides volans"|journal=Australian Journal of Ecology|volume=13(4)|year=1988|pages=445-450] Other predators include feral cats, which are not native to Australia, being introduced with the arrival of Europeans. [cite web|title=Greater Glider|url=http://www.wildlife.org.au/wildlife-gliders.php?page=w-gliders-greater.html|work=Gliders in the Spotlight|publisher=Wildlife Preservation Society of Queensland|accessdate=2008-05-05]

Within forests, males and females will have home territories and set borders between other members. For males, home territory ranges from 1.38-4.10 ha and is much larger when compared to females (1.26-2.97 ha). It was also determined that a patch area of viable forest will correlate to the respective size of home-territories; in large and small patches, the home territories will respectively be larger and smaller. [cite journal|last=Pope|first=M. L.|coauthors=Lindenmayer, D. B.; Cunningham, R. B.|title=Patch use by the greater glider (Petauroides volans) in a fragmented forest ecosystem. I. Home range size and movements|journal=Wildlife Research|volume=31(6)|pages=559-568|year=2004]

Distribution and habitat

The Greater Glider is found in southern Queensland, [cite journal|last=Wormington|first=K. R.|coauthors=Lamb, D.; McCallum, H. I.; Moloney, D. J.|title=Habitat requirements for the conservation of arboreal marsupials in dry sclerophyll forests of southeast Queensland, Australia|journal=Forest Science|volume=48(2)|year=2002|pages=217-227] eastern Australia, [cite journal|last=Taylor|first=A. C.|coauthors=Kraiaijeveld, K.; Lindenmayer, D. B.|title=Microsatellites for the greater glider, "Petauroides volans"|journal=Molecular Ecology Notes|volume=2(1)|year=2002|pages=57-59] southeastern New South Wales, [cite journal|last=Viggers|first=K. L.|coauthors=Lindenmayer, D. B.|title=Haematological and plasma biochemical values of the greater glider|journal=Australian Journal of Wildlife Diseases|volume=37(2)|year=2001|pages=370-374] and the montane forests of the Victorian central highlands. [cite journal|last=Incoll|first=R. D.|coauthors=Loyn, R. H.|Ward, S. J.; Cunningham, R. B.; Donnelly, C. F.|title=The occurrence of gliding possums in old-growth forest patches of mountain ash ("Eucalyptus regnans") in the Central Highlands of Victoria|journal=Biological Conservation|volume=98(1)|year=2001|pages=77-88] The Greater Glider is usually tracked via spotlighting on transects (considered to underestimate the actual population size), radio tagging and owl-call playback.

References

External links

* [http://www.wildlife.org.au/wildlife-gliders.php?page=w-gliders-greater.html WPSQ Wildlife page on Greater Glider (includes photo)]
* [http://www.wildlife.org.au/wildlife.php?page=w-gliders1.html Gliders in the Spotlight] — Wildlife Preservation Society of Queensland