Bettongia Lesueur Research Articles

Comparative erythrocyte metabolism in three species of marsupials from Western Australia

A comparative study was carried out to investigate various aspects of erythrocyte metabolism in three species of marsupials located in the western part of Australia. The burrowing bettong (Bettongia lesueur) and the Barrow Island euro (Macropus robustus isabellinus) were captured on Barrow Island whereas the mainland euro (Macropus robustus erubescens) was captured from the Pilbara region of northwest Western Australia. Aspects of erythrocyte metabolism studied included: levels of glycolytic intermediates, enzyme activities, sensitivity of erythrocytes to oxidants and methaemoglobin reducing capacity. Some important findings were: (1) no relationship was observed between haemoglobin and diphosphoglycerate levels; (2) both species from Barrow Island had lower levels of catalase than the mainland species; and (3) methaemoglobin reductive capacity was greater in the erythrocytes of the burrowing bettong compared to the two species of euro.

A Test of the Vegetation Mosaic Hypothesis: A Hypothesis to Explain the Decline and Extinction of Australian Mammals

The vegetation mosaic hypothesis suggests that medium‐sized mammals occupying arid and semi‐arid areas of Australia require a habitat that is a fine‐grained mosaic of different vegetation types or seral stages. This mosaic is believed to have been created in the spinifex deserts of central Australia by Aboriginal burning practices. Its loss in the period 1940–1960 is postulated to be a primary reason for both major reductions in range and mainland extinctions of many species of medium‐sized mammals at this time. This study measured the responses of three species of medium‐sized mammals to vegetation patterns within spinifex grasslands that ranged from comparatively uniform to highly diverse. The abundance, condition, and reproductive status of golden bandicoots (Isoodon auratus), northern brush‐tailed possums (Trichosurus vulpecula arnhemensis), and burrowing bettongs (Bettongia lesueur) were assessed within vegetation mosaics of various scales on Barrow Island, off the northwest coast of Australia. Scale of mosaic proved to have no significant effect on the numbers, condition, or reproductive status of any of the three species. Similarly, the creation of fine‐grained mosaics of early seral‐stage vegetation mixed within climax vegetation by extensive oil‐field operations over nearly half the island had no significant effect on the number or condition of animals. Hence, scale of mosaic seems unlikely to be related to the mainland decline or extinction of these species. The pattern of decline and extinction on the mainland but continued survival on offshore islands is more consistent with the presence (mainland) or absence (islands) of introduced predators (foxes and cats) and herbivores (rabbits and stock).

Relict Surface-Soil Features in Semi-Arid Mulga (Acacia Aneura) Woodlands.

The physical dimensions and locations of two forms of circular surface-soil features, believed to be constructed by animals now locally extinct, are described for a 200 ha site and its environs in a semi- arid mulga (Acacia mura) woodland in north-western New South Wales. The most common were 48 circular (c. 10 m diameter) features, some with well-defined central depressions carrying vigorous grass tussocks. Soil chemical analysis indicated the relatively high fertility of these central depressions. Surface pebbles were analysed for comparison with similar lithological data in the literature. The evidence suggests that the malleefowl (Leipoa ocerlata) is the most likely agent responsible for building these features. While only four of the larger features (c. 30 m diameter) were located in the study site, they were particularly conspicuous on higher ridges in adjoining paddocks because of the abundance of highly reflective, calcrete fragments visible on the surface of subcircular mounds. It is postulated that they were constructed by the bumowing bettong (Bettongia lesueur).

The distribution and abundance of the burrowing bettong (Marsupialia : Macropoidea)

The burrowing buttong (Bettongia lesueur) has been extinct on mainland Australia since the early 1960s, but was believed to persist on four islands off the coast of Western Australia-Bernier, Dorre, Barrow and Boodie. We surveyed these islands in 1988-89 to ascertain the status of bettongs and other endangered mammals. Bettongs were widespread and comparatively abundant on three islands but absent from the fourth. Bettongs occurred at estimated densities of c. 14-17km-2 on Bernier, Dorre and Barrow Islands, suggesting approximate minimum populations of 650, 1000 and 3400 respectively and a total minimum population for the species of c. 5000 individuals. It would appear that a poisoning campaign in 1985 to eliminate Rattus rattus from Boodie Island also eliminated the bettong. The burrowing bettong has apparently been absent from a fifth island and its type locality, Dirk Hartog Island in Shark Bay, since early this century. The vulnerability of this species is highlighted by its extinction on mainland Australia and by the loss of two of its five island populations. It now occupies less than 0.01% of its historical range. Its status as rare and endangered is justified.

Anatomy of the Stomach in Three Species of Potoroinae (Marsupialia: Macropodidae).

Stomachs of Potorous tridactylus, Bettongia lesueur and Aepyprymnus rufescens were dissected in situ. The general organization in all three species is very similar. The oesophagus opens into the tubiform fore stomach near its caudal end. The sacciform fore stomach region lies to the left of the abdomen; in adult animals it contains about 75% of the total gastric volume. Taeniae, haustra, and semilunar folds differentiate the wall of the sacciform fore stomach, but are absent from the tubiform fore stomach. Aborally the tubiform fore stomach is followed by the hind stomach, which is lined with fundic and pyloric glands. Both fore stomach regions are covered with cardiac mucosa. The potoroine stomach is different from the macropodine type, which has a small sacciform fore stomach and a long tubiform fore stomach, both with taeniae, haustra, and semilunar folds. The differences of the gastric anatomy in relation to differences in food and in biotopes are discussed, as well as the possible evolution of both types of macropodid stomachs.