Memorandum. 10th May
FISHERIES & WILDLIFE
11 MAY 1962
Report on the known distribution of Gymnobelideus leadbeateri from observations in the Marysville district up to May, 1962.
The present limits of the colony, as indicated on the attached map, have been determined from observations made by members of the Fauna Survey Group of the F.N.C.V. and by myself. The three specimens at present housed in the Wildlife Laboratory were obtained from about the centre of this distribution.
The initial observation, reported by Wilkinson in the Vic. Nat. 78: 99, was made at Cumberland Valley. No further sightings in this locality have been reported, however Gymnobelideus has been observed in numbers on many occasions in the Tommy's Bend area. The survey work has been done only along the roads in the area. At this stage it is impossible to say just where the limits of the possum's disribution occur; it appears however that it is confined to Mountain Ash (E. regnans) forest.
Vegetation: At the western end of the mapped distribution the character of the vegetation changes from Mountain Ash-Messmate to Messmate-Stringybark forest. Some distance from the eastern extremity of the range Shining Gum (E. nitens) becomes the dominant eucalypt. As yet the possum has not been seen in either the Stringybark or the shining Gum areas. There is a recurrence of E. regnans in the Cumberland Valley.
The physical nature of the Mountain Ash forest in the Tommy's Bend area is worthy of note as it appears to be a particularly suitable habitat for a possum with the characteristics of Gymnobelideus. Much of it is composed of saplings about 30 to 40 feet in height, frequently occurring in dense thickets. There are numerous, over-mature trees, some exceeding 200 feet in height. Many of these are dead, dry trunks with few upper limbs left. there is often an extensive understory of wattles and other small trees which form an almost continuous foliage layer well below the eucalypt canopy.
Gymnobelideus is extremely active and moves about the trees with great speed and agility. It appears to rely largely on the grip of the large toe-pads of the manus and pes, the latter having the third digit quite elongate. This allows the possum to secure a very sure footing while leaving the hands free for feeding etc. Thus Gymnobelideus is well adapted for movement on thin branches and narrow trunks of saplings and small trees. The denseness of the understory and the canopy above enables the possum to range through the forest without decending to the ground. It is thought that night flying moths form part of the diet, in which case the nature of the vegitation permits rapid pursuit of slow-flying insects by such an animal with no other means of progression. (Compare with the Suger Glider, Petaurus breviceps, which also eats moths, sometimes leaping from a branch to seize on in mid-air).
It is suspected that the old, dead trunks with hollows and spouts are the nesting sites of Gymnobelideus. In this respect these old trees are important to all other species of the Phalangeridae that occur in the area, namely, Mountain Possum, Trichosurus caninus; Ringtailed Possum, Pseudocheirus laniginosus, Greater Glider, Schoinobates volans; Sugar Glider, Petaurus breviceps and Feathertailed Glider, Acrobates pygmaeus.
Control of the area: is vested in the Forests Commision and the M.M.B.W. The Green areas on the attached map represent Permanent Forest, the pink area the O'Shannassy catchment, M.M.B.W. Reserve granted 28.1.1910.