A comparison of the behaviour and ecology of the Tasmanian bandicoots, Perameles gunii (Gray 1838) and Isoodon obesulus (Shaw and Nodder 1797)

The study of the behaviour and ecology of marsupials has been a neglected area of research for a long time and few quantitative studies of this subject have been undertaken to date. However, recently (particularly during the past twenty years), there has been a recrudescence of interest in these spheres of investigation as the ensuing review of the relevant literature shall demonstrate, although the amount of this research-effort is still meagre in comparison with the volume of information published about many species of eutherian mammals. This neglect of research on marsupials is both surprising and unfortunate, as marsupials are widely distributed, occupy all of the major habitats occurring in Australia and have adapted diverse modes of life almost, if not precisely comparable in variety to that of analogous eutherian mammals occupying comparable ecological niches. Earlier studies on marsupials were of a comparative nature often specifically dealing with differences between metatherian and eutherian mammals. In addition, these investigations mainly concentrated on only a few species, particularly the larger members of the family Macropodidae (the kangaroos and wallabies) and the Virginia opossum, Didelphis marsupialis. Research-activities were further limited by the fact that these studies were largely centred on reproduction, a process of considerable importance in view of its uniqueness in marsupials. It is the above factors and the fact that the majority of other marsupials are nocturnal, timid and cryptic, (rendering investigations difficult, particularly in the field) that have resulted in the paucity of behavioural and ecological information available on the numerous diverse groups of the sub-class Metatheria. As previously mentioned, D. marsupialis has received considerable attention, being the only specie of marsupial endemic to North America. Investigations have covered behavioural characteristics and seasonal changes in behaviour (McManus 1970, 1971), the daily activity cycle (Bombardieri and Johnson 1969) and population density and movement patterns (Holmes and Sanderson 1965; Shirer and Fitch 1970). Studies on the family Macropodidae have included observations on daily activities and social behaviour of Macropus rufus (Frith 1964; Russell 1970a; Croft 1981a), agonistic encounters and social behaviour in M. giganteus (Grant 1973; Kaufmann 1975) and locomotion in several species of the larger macropods (Windsor and Dagg 1971; Alexander and Vernon 1975). Locomotion has also been observed in the genus Potorous by Buchmann and Guiler (1974). Russell and Pearce (1971) studied the investigation of novel objects by selected species of four marsupial families, of which two species belonged to the family Macropodidae and 2 one to the family Peramelidae. Observations have been made in captivity on the quokka (Setonix brachyurus), the pademelon (Thylogale billardierii) and the burrowing bettong (Bettongia lesueuri) by Packer (1969), Morton and Burton (1973) and Stodart (1966), respectively and Kitchener (1973) has investigated the home ranges and movements of S. brachyurus and P. apicalis. By comparison, all of the other families of marsupials have received scant attention. Studies on the family Dasyuridae have been mainly concerned with prey-killing and feeding behaviour in Dasycercus cristicauda (Ewer 1969) and in Sarcophilus harrisii (Buchmann and Guiler 1977). Hutson (1975) investigated sequences of prey-catching in Dasyuroides byrnei and in 1976 he also presented an account of maintenance activities in the same species, as did Moss (unpubl.) in a study of Dasyurus viverrinus. The ecology of S. harrisii was described by Green (1967) and its home range and movements by Guiler (1970a). The smaller representatives of the family have received some attention in that investigations of certain aspects of the behaviour and ecology of Antechinus stuartii, A. minimus and A. swainsonii have been conducted by Marlow (1961), Braithwaite (1974, 1979), Hocking (unpubl.) and Haynes (in press). Hall (1980) studied the diets of two sympatric species of Antechinus. Finally, the family Peramelidae (bandicoots), forming the subject of the present investigation, has received a small amount of attention with respect to their behaviour and ecology. Lyne (1964a) and Stodart (1966a) studied the breeding of Perameles nasuta in captivity. Heinsohn (1966) and Braithwaite and Gullan (1978) investigated the ecology of P. gunnii and Isoodon obesulus. Reproduction was also studied in I. macrourus (Mackerras and Smith 1960; Lyne 1974) and observations on the behaviour of the same species were undertaken by Day, Kirkby and Stenhouse (1974) using an open field arena. Activity-patterns and social behaviour were analysed in I. obesulus (Watts 1974, O'Callaghan, unpubl.) as were ranging movements in I. macrourus (Gordon 1974). Discrimination-reversal learning in I. obesulus was investigated by Buchmann and Grecian (1974) and studies of other behavioural and ecological aspects undertaken included burrowing in I. obesulus (Kirsch 1968), feeding and foraging in I. macrourus (Anon. 1970), the status of P. gunnii in Victoria (Seebeck 1979) and grooming in I. macrourus (Clarke and Clarke 1969). Lyne (1951, 1952) described the external characters (particularly of pouch young) of P. gunnii and four other species of bandicoots and Stoddart and Braithwaite (1979) made a study of the utilization of regenerating heathland habitats by I. obesulus. In view of the relative lack of detailed information on members of the family Peramelidae the present investigation was undertaken to examine two distinctive but comparable species of the family. Heinsohn (1966) described the same two species, Isoodon obesulus and Perameles gunnii as being sympatric. Consequently this study is an attempt to provide quantitative data on four specific aspects of their behaviour and ecology, in order to acquire a general appreciation of the relationship of the two species to their environment and to each other. The aspects investigated were maintenance activities (Chapter 3), feeding behaviour and diet (Chapter 4), home ranges and habitat utilization (Chapter 5) and intra- and inter-specific interactions (Chapter 6) . It was hoped and is the avowed aim of this study, that a comparison of these aspects may assist in explaining why these two species are able to co-exist in the same habitat while presumably utilizing somewhat similar resources.