Feature Article - The Marsupials of Tasmania
Feature article published in the Tasmanian Year Book, 1969 (cat. no. 1301.6)
Mammals and Marsupials
The Sub-Classes of Mammals
Mammalia was the term invented by Linnaeus in 1758 to include that class of animals in which the young are brought forth alive and nourished with milk from the mother’s breasts. At this point of time, two mammalian sub-classes were known, the first including man, monkeys, dogs, whales, cows, etc. and the second the marsupials, their existence having been established in 1500 by the Pinzons when they took a Brazilian opossum back to Granada. The discoverers of Australia then slowly expanded the coverage of the marsupial sub-class by reporting kangaroos, wombats, bandicoots, 'opossums’ and the wolf-like thylacine.
The Australian continent was also the home of the platypus and the echidna with the result that a third mammalian sub-class had to be formed, these egg-producing creatures satisfying other mammalian criteria (which had now been expanded beyond the mere mechanics of reproduction).
Tasmania’s indigenous fauna provides examples of all three mammalian sub-classes:
(i) Prototheria, represented by Ornithorhynchus anatinus (platypus) and Tachyglossus setosus (an endemic species of echidna);
(ii) Metatheria, represented by 19 species of marsupials of which seven are endemic;
(iii) Eutheria, represented by 5 species of native rodents and six species of bats. An important distinction between Tasmania and continental Australia is the absence, in this island, of two eutherian predators: the dingo, widespread in Australia when the first white settlers arrived, and the fox, introduced by the settlers there in the nineteenth century.
The term marsupial is applied, in general, to animals which, after bearing young in an immature state of development, suckle the offspring in a pouch. Thus the young of marsupials, from conception, may be traced through two stages: (i) gestation; (ii) pouch life; in the case of the Tasmanian devil, for example, gestation is about 31 days and the pouch life about 4½ months.
In the larger marsupials, for example the kangaroo, the new-born are small and poorly developed, except for the fore-limbs which are proportionately very large and tipped with strong claws; the hind legs at this stage may be only embryonic buds. The young are about an inch in length, naked of fur, blind and with ears hardly visible. The female kangaroo, at parturition, sits with her tail brought forward between her legs and spends some of her time scratching at her pouch and licking it. When the offspring emerges from the cloaca, it climbs by its clawed fore-limbs into the pouch and reaches the teats, one of which it eventually fastens to with its mouth.
The tip of the teat expands within the mouth so that the young kangaroo cannot be released without rupturing the sides of its mouth and, for a start, the body grows without any corresponding increase in the size of the mouth. The end of the offspring’s pouch life draws near when it is freed from the teat; it then begins to eat vegetation by leaning from the pouch when the mother herself is feeding.
The pouch itself exhibits considerable variety, opening downward or backward in some marsupials, or forward or upwards in others; the kangaroos, for example, which rest in a sitting position, have pouches opening upward.
The period of dependency of offspring does not necessarily end when the young leave the pouch. For example, young bandicoots live on in the mother’s nest until they are able to look after themselves.
Isolation from Mainland
About 30,000 years ago, a great increase in the volume of world ice caused shorelines to fall hundreds of feet below their existing level. Eventually the melting of this ice reversed the process and a slow, great flooding began, one result being the formation of Bass Strait and the isolation of Tasmania as an island. By interpolation on recently published curves for world sea level changes, this event dates back about 11,000 years.
Because of this land link in comparatively recent times (in terms of the geological time scale), it is not surprising that Tasmania should have few endemic marsupials. The two most quoted examples are the Tasmanian tiger and the Tasmanian devil (Thylacinus cynocephalus and Sarcophilus harrisii) but allied species are known to have lived in continental Australia, despite the fact that they were extinct there before white settlement began. It is true that, putting aside the tiger and the devil, there are five other endemic marsupial species but these are closely related to corresponding continental species. All Tasmanian marsupials are indigenous with one exception; the exotic species is the sugar glider or flying possum, Petaurus brevicaps, Victorian specimens having been brought to the island in the period 1835-1837 as pets, only to escape and take to the bush.
Arrangement of Species
The pouched mice, native cats, Tasmanian tigers and Tasmanian devils all belong to the family Dasyuridae, a group of the superfamily Dasyuroidea. However, the grouping of the Tasmanian marsupial species in the sections that follow is not made in conformity with any scientific principle but is based, in the main, on the common names of the animals (e.g. ‘possum’ as a heading covering five species, the nexus being the fact that the common name of each contains the word possum).
The Major Carnivores
The Tasmanian Tiger apparently earned this title from the 13-18 stripes on the rump but the animal is much more akin to a very large dog or a wolf if an analogy must be sought. The tail is long, rigid and slightly compressed laterally. Thylacines of up to six feet total length have been known.
Thylacines are carnivorous animals and naturally turned to sheep killing in the days of early settlement; from 1888 the government paid a bounty of $2 per head for them and they were vigorously hunted up to the turn of the century. From about 1914 the species became very rare whilst today, for all practical purposes, the animal is extinct. Reported sightings still are investigated from time to time and the discovery of pad marks and other evidence have revived hope that the species may still exist; for many years now, however, no capture has been made. To most Tasmanians, the tiger is only a picture in a book but some of the older generation had the opportunity of seeing live specimens in a Hobart zoo in the 1920s.
(2) Sarcophilus harrisii
The early settlers were unable to adequately compare this animal with anything in their experience and therefore coined the name Tasmanian Devil; the head, equipped with massively strong jaws, is large and broad at the base and this makes the hind quarters appear relatively weak and out of proportion. The devil is black with white chest, shoulder and rump markings although occasionally all-black specimens are found.
Unlike thylacine, the devil is still very common, particularly on the west coast and in the north-east, and is spreading into other areas where it had not been seen in living memory. The animal is carnivorous and not fastidious, so in disposing of prey or carrion it eats the lot - skin, fur or feathers, and intestines; its sight is better adapted to night hunting and is defective in daylight.
March is the main breeding month and three or four young are born after a gestation period of about 31 days. The offspring are then reared in the pouch for about 4-5 months. It has been observed that, in captivity, the male eats the young; possibly in the natural state, the male is driven from the den when offspring are being reared.
(3) Dasyurus maculatus
Tiger Cat is not a happy choice of name for this animal; the head is most ‘uncatlike’, resembling more that of a weasel or similar species and its characteristic spots, on body and tail, are most ‘untigerlike’. Possibly the tiger prefix is a tribute to the creature’s reputation as a courageous and fierce fighter. Specimens of up to four feet in length have been recorded; the animal is usually dark brown in colour although black varieties are common. It is a good tree climber and can therefore rifle birds’ nests but it preys also on small mammals and reptiles, with poultry yards as occasional targets.
The main mating months are June-July, with gestation lasting about three weeks. The tiger cat’s pouch contains six nipples in which four to six offspring are reared for a further three months. The species is widely distributed in the eastern States from mid-coastal Queensland to Tasmania; within the island, it is widespread but not as common as the native cat.
(4) Dasyurus quoll
The Native Cat (D. quoll) has a spotted body but not a spotted tail, and this is the easiest way of distinguishing it from the Tiger Cat (D. maculatus); in general, it is smaller and less fierce than the latter. Specimens range in colour from sandy through olive-grey to black, but the lighter spots are always present.
The main breeding months are from late May to early August and 20 to 25 embryos may be born, of which only six have a chance of living by attaching themselves to nipples within the pouch. The species is widespread in the eastern States from N.S.W. to Tasmania; it occurs also on King Island.
(5) Trichosurus vulpecula
The Brush Possum is not so exclusively arboreal as the ringtail and spends some of its time on the ground. Its long, bushy, prehensile tail has the inner surface naked at the end and this helps distinguish it from the ringtail which has a tail covered by short hair and marked by a prominent white tip. In general, brush possums are larger than ringtails and range in colour from grizzled grey through rufous brown to black, the underside being invariably lighter; the black specimens are usually found in the wetter parts of the island. Cream or silver colouring has occasionally been recorded.
The female breeds twice a year, March and August being the main months, and the gestation period is 16 to 21 days. Since the offspring, usually one or sometimes two, remain in the pouch for five months, female brush possums taken at any time of the year are likely to be carrying young. The species is widespread throughout Tasmania and found also in eastern Australia.
(6) Pseudocheirus convolutor
The Ringtail Possum can be distinguished from the brush possum by its tail (see previous section), and varies in colour from dark grey to dark brown or even black. More strictly arboreal than the brush possum, it is widespread in Tasmania but is thought to suffer severely from natural population cycles; the numbers fell off greatly about 1951-52 and have been slow to recover. The ringtail lives in most types of country except plains and possibly rain forest. Eucalypt leaves and young shoots form the main item of food; if it raids an orchard, the ringtail will attack young shoots.
Young are found in the pouch during most months of the year, but especially in winter. Gestation may result in the birth of as many as six young but only two can survive (the pouch contains four teats but only two are functional). The species is found also in the Bass Strait islands but not on the mainland of Australia; however, a related species lives there.
Ringtail and brush possums are hunted for their skins but are partially protected by short game seasons (or total prohibition for a year or series of years, as for the ringtail). Other species given the name possum are described in the following sections.
(7) Cercaertus nanus
The Pigmy Possum (C. nanus) is less than six inches in body length and is hard to distinguish from an allied species, C. lepida. The ears of nanus are broader and larger, and lepida is the smaller in body length, the snout-rump length being less than three inches. One peculiarity of both species is a swelling of the tail at the base, especially in autumn, due to the deposition of fat.
The pigmy possum makes a nest in the bark of trees and lives on nectar, blossom and insects; it hibernates for a period in winter. The species occurs also in the eastern States as far north as south-east Queensland and in S.A. but little is known of its Tasmanian distribution; Tasmanian specimens have been recorded at Cullenswood in the north-east and Franklin in the south.
(8) Cercaertus lepida
The Little Tasmanian Pigmy Possum (C. lepida), on superficial examination, appears to be a diminutive of C. namus but there is sufficient differentiation to label it as a separate species. Specimens have been caught in places as widely separated as Tyenna and Port Davey in the south and near Launceston in the north. The species is confined to Tasmania.
(9) Petaurus brevicaps
The Sugar Glider, often called the flying possum, is readily distinguished by the beautiful, soft, dove grey fur and by the presence of the gliding membrane which runs down the side of the body. The tail is long and bushy with a dark tip. A dark stripe runs along the head and down the back. The species is not a native of Tasmania and was introduced from Port Phillip into the north by travellers who had made pets of the creatures in the period 1835-1837.
The creature lives on insects, fruits, buds and blossoms, and the female bears two offspring each season, usually in June or July. It is now widely distributed in Tasmania and is found in the eastern States of Australia, and even in the Northern Territory.
(10) Antechinus swainsonii
The Dusky Marsupial Mouse is dark brown in colour with a lighter belly; it has small ears and white on its tail which is hairy and almost as long as the body. The relation of tail to crown-rump length establishes the distinction between A. swainsonii and A. minimus; in the former species, the tail is shorter than this length, in the latter, longer. The snout-rump length is known to be as great as six inches in A. swainsonii.
Eight or nine young are born in July or August and are carried in an incomplete pouch for some seven to eight weeks; the offspring then commence nest life when their eyes open and their fur has developed. The species has been recorded at Maydena, Orford, Nietta, Lake St Clair, Dromedary and Sandy Bay but, due to its habits, it is rarely encountered. There are two races of this species, the one confined to Tasmania and the other occurring in the highlands of Victoria and N.S.W. The mainland race has thinner fur and the underside is dark brown with a red-yellow tinge.
(11) Antechinus minimus
The Little Tasmanian Marsupial Mouse can be distinguished from A. swainsonii by the tail relationship described in the previous section; in general, A. minimus is a smaller species and is characterised by a blunter face. The species is confined to Tasmania and the Bass Strait islands.
(12) Sminthopsis leucopus
The Whitefooted Sminthopsis has a very sharply pointed snout, white feet and a white and hairy tail, tufted at the tip. The body is dark grey to black, but the snout and ears are fawn colour. The species is rarely encountered but is distributed in the eastern States from Victoria to south Queensland; recent specimens have been recorded at Hawley in northern Tasmania and at Orford in the east.
(13) Perameles gunnii
The Barred Bandicoot is easily recognised by having four or five dark bars across the rump; the tail is short, the snout long and the ears are almost rabbit-like. The colour is light whitish fawn, the bars are dark brown and the tail and undersurface near white. The animal lives in open country and lightly timbered areas in nests constructed in grass tussocks; its main food is vegetable matter and insects.
Three or four young may be born at any time of the year and the pouch has eight teats. The period of immaturity is spent first in the pouch and later in the nest. The species is widely distributed in Tasmania in suitable country but is not found in continental Australia; it closely resembles a mainland species, the eastern barred bandicoot, P. fasciata.
(14) Isoodon obesulus
The Short-nosed Bandicoot is usually light brown, coarse-haired and near white underneath; the tail is short, thinly furred and somewhat scaly. The absence of dark bars on the rump easily distinguishes it from Perameles gunnii.
This animal tends to live in thick scrub country where it makes a nest of twigs, leaves and earth to blend with the surroundings; it is mainly an insect eater and digs after its prey. It is a hopper, rather than a walker, moving both hind feet simultaneously and is chiefly nocturnal in habit.
The main breeding season is in June and July, with four offspring as the usual outcome. The pouch has eight nipples and the young, after leaving the pouch, live on in the nest. The short-nosed bandicoot is widely distributed not only in Tasmania but also in the eastern States.
Wallabies and Kangaroos
(15) Wallabia rufogrisea
Bennett’s Wallaby has a long face and long ears; the tips of the ears and the end of the snout are dark. The usual colour is reddish brown with a grey undersurface, though grey and dark individuals are common. The back is often greyish. This species can be distinguished from the pademelon (Thylogale billardierii) by the foot length: between 150 and 250 mm in the wallaby, but under 150 mm in the pademelon; another difference is that the pademelon’s face and ears are much shorter and the snout blunter.
Bennett’s Wallaby inhabits relatively open country (when compared with the pademelon which prefers the thicker scrubs) and is often wrongly called a kangaroo. The main breeding months are January and February, gestation lasting about 40 days. One young is usually carried though twins are not uncommon and triplets have been recorded. Life in the pouch is very prolonged and the young do not leave it before November or December. The species is very widely distributed in Tasmania in open savannah woodlands, coastal scrub, sclerophyll forest and on the fringes of pastoral clearings. A species of the same name (W. rufogrisea) is found in continental Australia but the mainland wallaby is larger in size and has a shorter coat. The Tasmanian animal is sometimes referred to as W. r. bennetti.
(16) Thylogale billardierii
The Pademelon is usually called a wallaby but the previous section gives the way of distinguishing it from a true wallaby; its colour can be one of many shades of brown, with dark reddish brown the most common. The ventral surface tends to be yellow-brown or reddish.
Breeding takes place in the summer but young may be found in the pouch throughout the year; only one young is usually carried. The animal is widespread in Tasmania, preferring the thicker lower scrubs for its habitat.
(17) Macropus giganteus tasmaniensis
Tasmania has only one species of kangaroo, the Forester Kangaroo, and it can easily be distinguished by its size, often five feet or more in height. The colour is grizzled grey and the fur is rather coarse; the nose is hairy.
The main mating month is December, the gestation period lasting about 40 days. Life in the pouch is very prolonged and the young quit it after about ten months. The Forester Kangaroo was once very widespread in Tasmania but is now confined to the north-east and east; it is a wholly protected species. The species Macropus giganteus is widely distributed in continental Australia and tasmaniensis is a sub-species.
(18) Bettongia cuniculus
The Bettong is the largest of the rat kangaroos and superficially resembles a small wallaby; the easiest distinguishing feature is the tail, which, in the bettong, is laterally compressed and usually white-tipped. Another animal it resembles is the potoroo and in this comparison, the basic relationship is between hind foot and head; in the bettong, the hind foot is longer than the head but, in the potoroo, the hind foot is shorter.
The face of the Bettong is shorter than that of the potoroo and the animal ranges in colour from sandy to dark brown, with the undersurface lighter. The species is widely distributed and lives on the fringes of forests or in lightly forested areas, as compared with the potoroo which prefers low thick scrub and the fringes of rain forests. Bettongs are nest builders, using bark or grass, and eat mainly roots; favourite sites for nests are hills exposed to the sun, with light timber and grass cover.
The breeding season is long, from at least March to December, and the gestation period is about six weeks; the one young spends about four months in the pouch, although twins are sometimes carried. The species is confined to Tasmania and is sometimes known as the Tasmanian rat kangaroo.
(19) Potorous tridactylus
The Potoroo can be distinguished from other macropods by the hind foot being shorter than the head; the snout provides an alternative name, long-nosed rat kangaroo. The usual colour is dark brown, with the under-surface greyish brown. The animal avoids open country and inhabits thick scrub where its diet is mainly roots.
The gestation period is about 35 days, when one young is born; it then lives in the pouch for about 135 days. The pouch contains four nipples and young may be found in the pouch of captives taken at any time of the year. The potoroo is widely distributed in Tasmania and was once common in the eastern States but is now believed to be almost extinct there.
(20) Phascolomys ursinus
The Wombat is often called a badger, on account of its robustness and burrowing habits, but it far excels the true or placental badger in strength and in ability to dig deep tunnels with great rapidity. The animal is squat and bear-like in shape, powerfully built and with a very small tail. The usual colour is brown though grey and buff variations occur.
The animal usually lives in a burrow, though caves or piles of rocks may also serve for a den; it feeds on herbage and grasses and prefers open forest country or rocky areas, from sea level to as high as 3,000 feet. It avoids thick rain forest, probably to get freedom of movement. The wombat family is widespread in Tasmania and on the Australian continent, but its reproductive habits are not completely known; the young, usually a single individual, is born in the autumn, but there are two nipples available for suckling.
The preservation of the State’s indigenous animals is a major aim of the Animals and Birds Protection Board and, under State legislation, species may be declared wholly protected or partially protected. Wholly protected marsupial species include the pouched mice, the pigmy and flying possums, the native cats, the Tasmanian tiger and devil, the bandicoots, the Forester kangaroo, the bettong and the potoroo.
The brush possum and the ringtail possum are partially protected species, the animals being hunted for their skins; ‘partially protected’ means that the Board can nominate the opening and closing days for the hunting period, or alternatively keep the season closed for years at a time. The main consideration is the survival of the species and, due to low ringtail numbers, there has not been a season declared for some time. The two wallabies, Bennett’s and the pademelon, are also partially protected, the question of open or closed seasons being a little more complex; not only are they hunted for skins and meat but, if allowed to thrive on the fringe of settled areas, they become a pest, attacking farmers’ crops and competing with farm animals for the grass and herbage on pasture lands. The wombat is not protected but the survival of the species is assured; the animal, being a burrower, is something of a nuisance on farm properties but is not hunted for skin or meat in the bush and few would destroy this harmless, attractive creature without good reason.
In addition to the protection measures just described, there are, of course, national parks and game sanctuaries where no hunting or destruction is allowed at any time of the year.
In the 1967 season, the number of skins taken by hunters was: possum, 104,488; wallaby, 26,308; pademelon, 30,122. The police, who issue hunters’, sellers’ and dealers’ licences, obtain a count of skins from royalty payment collections.
(Further reading: (i) Marsupials of Tasmania, author Dr E. R. Guiler, booklet of Tasmanian Museum and Art Gallery. (ii) Marsupials, article in Encyclopaedia Britannica.)