Ray Williams. School of Biological Science, University of New South Wales P.O. Box 1, Kensington, New South Wales 2033, AustraUa

Transcription

1 Carnivorous Marsupials Ray Williams School of Biological Science, University of New South Wales P.O. Box 1, Kensington, New South Wales 2033, AustraUa QJ There are nearly 50 species of carnivorous marsupials or dasyurids in Australia ranging in size from the Tasmanian Devil Sarcophilus harrisii (which is about the size of a small dog) to one of the smallest mammals in the world, the Long-tailed Planigale Planigale ingrami that, in some populations, weighs only 4-5 grams. These carnivorous, and insectivorous, animals are represented in most habitats across the continent Because of improved trapping techniques, namely the use of pit fall traps, particularly in arid and semi-arid regions, many small dasyurid species have been found to be common when once they were considered rare. This has led to a wider variety of species finding their way into animal houses for research and zoos for display. Several new species have also been described. For example in 1983, 12 species of Sminthopsis or dunnarts were listed in R. Strahan's "Complete Book of Australian Mammals". In 1986, Van Dyck described a new dunnart, the Chestnut Dunnart Sminthopsis archeri, and noted that 17 species were recognized. Morton, Dickman and Fletcher (1889) recognize 18 species of Sminthopsis.

2 For the purpose of this discussion, I have divided the carnivorous marsupials into three main groups: (i) Large species (approximately 300 g-8 kg), i.e., the Tasmanian Devil and quolls or native cats (4 species); (ii) Medium-sized species (approximately g), i.e., phascogales (2 species); the Kowari and Mulgara; antechinuses and pseudantechinuses (12 species); and (iii) Small species (approximately 4-40 g), i.e., dunnarts (18 species); ningauis (3 species); planigales (4 species). There have been informative papers written on the subject of dasyurid husbandry (Woolley 1979, Aslin 1979) to which readers are directed. Here 1 will deal mainly with my own personal experiences of caring for carnivorous marsupials over the past 18 years. Before acquiring any native animal I suggest that thorough research into the species is essential. Information on the natural habitats, breeding, feeding habits and disposition towards each other all helps in the construction of a suitable cage, feeding regime and planning a breeding programnpe. A wealth of information can be found in review papers (e.g., Morton, Dickman and Fletcher 1989) and in research papers where, if the animal was kept in captivity, the author often describes the techniques used to maintain the subject. Of course there are also a number of dasyurid species about which we know very little. HOaSING Larger Dasyurids Tasmanian Devil and Quolls These species are best kept singularly or in breeding pairs. During periods of activity they are energetic animals and require as much space as possible. A minimum floor area should be three square metres. Some species, for example the Spotted-tailed Quoll Dasyurus maculatus, are semi-arboreal so the height of the cage should also be considered. Most larger species enjoy sunbaking so ideally an indoor observation cage with access to an outside run should be provided. Because the large species have been known to chew through wire netting, cages should be constructed out of steel pipe frames covered with link- or weld-mesh (2.5 cm mesh size). Wooden door frames and doors may also be chewed. At the University of New South Wales, Tasmanian Devils and Spotted-tailed Quolls have been successfully kept by modifying existing cages. Tasmanian Devils were kept indoors in pens measuring 2.5 m x 1.3 m. Existing wire-netting fences were covered with galvanized steel sheets 1 m tall. An overhang of steel had to be added to this after one animal moved its nestbox to the edge of the cage and escaped through the wire netting, fortunately without devouring any of the other occupants of the animal house. Spotted-tailed Quolls were housed at the University in outdoor steel and weldmesh cages 2.2 m X 0.75 m x 1.7 m high. Access to indoor nestboxes was provided. At the University's Field Station at Cowan, they were housed in a series of three cages constructed of steel pipe and linkmesh 4.5 m x 1.5 m with a mesh size of 1.8 cm. These cages were originally built as a home for sick and injured birds but have proved to be excellent all purpose cages. The rear one-third of two of the cages is fully enclosed providing plenty of shelter. To prevent escape, a double gate system is suggested, especially if the cages are outside.

3 It has been found from zoo experience that dasyurids kept on concrete floors suffer from sore feet so animals should be kept on wooden or dirt floors. The wooden floors can be hosed down regularly; with dirt floors, soiled areas should be removed frequently. Fortunately most dasyurids defecate and urinate in the same spot making this task easier, although periodic change of the soil is often necessary. The soil can be covered by leaf litter or pine bark. A nestbox and heavy water bowl are essential and logs and rocks should be made available. SmaU and Medium-sized Dasyurids 1 have kept a range of species of carnivorous marsupials in appropriately sized aquaria (Fig. 1). Obviously, the rule "the bigger the better" applies. Lids are covered in metal flyscreen for planigales and ningauis and 1 sq. cm weldmesh for other species. Larger species can chew through flyscreen. The aquaria are landscaped using fine sand (particularly for desert species), rocks, grass tussocks, hollow logs and bark. Artificial nestboxes are sometimes provided. Nest material Fig. 1. Aquarium-type cage used to maintain and breed small to medium-sized camivorous marsupials in captivity at Cowan Field Station. A Brown Antechinus Antechinus stuartii is shown here feeding on Wombaroo Small Carnivore Mix.

4 70 should also be available. Some species (e.g., species of Antechinus) make large nests from dry leaves so these should be provided. 1 have found that by providing an interesting environment for the animal, displacement activity such as pacing of the cage is avoided. Choice of sand is important. For inland species, red sand collected from Fowlers Gap, western New South Wales, is used. Most dasyurids have been observed to sand bathe which helps keep the fur in good condition. Animals kept on sawdust or other coarse substrates often develop matted fur which can eventually cause death. Coarse building sand should be avoided because it is too abrasive and results in sore feet. Water should always be available. Because water bowls are easily tipped over or fouled, a watering system can be installed. A reservoir of water supplies each group of cages through plastic tubing and modified, spring-loaded drinking nozzles (C. F. Maddock and Co. Pty Ltd, Mona Vale, NSW). Problems associated with using aquaria include poor ventilation, the difficulty of stacking cages and, being glass, the problem of partitioning the cage. One advantage is that they are easy to clean, except those that are large and heavy. For small species, such as planigales, ningauis and dunnarts, modified plastic mouse cages (55 cm X 33 cm X 19 cm high) can be used. These are easily cleaned and well ventilated. At the University of New South Wales these are housed on racks and watering is by tubes (see above). One disadvantage is that landscaping of the cage is not easy because of the lack of height For medium-sized animals, such as the Kowari Dasyuroides byrnei, glass-fronted, wooden breeding cages are provided. These measure 114 cm X 63 cm X 63 cm high and, with ventilation in the sides, these can be stacked on top of each other. The cage is divided in the middle and has a small sliding door to allow the introduction of a mate. At Cowan Field Station we are also trying groups of Kowaris in large, pit-like cages 2.4 m x 1.5 m. Three walls are made of galvanized steel (1 m tall); the fourth is the existing fibro wall of the laboratory. DIETS The following diets for dasyurids have been successfully used at the University of New South Wales over the past ten years. Other similar but more elaborate diets have been published (e.g., Woolley 1979, Aslin 1979) but we have found some of the components unnecessary. Medium-sized and Small Dasyurids Meat Mix given daily. Lean minced meat (kangaroo) Dry dog food (powdered) Calcium carbonate Mineral and vitamin supplement Mice for medium-sized species. Once or twice per week if available this replaces the meat mix. Live insects in addition to meat mix and when available. Mealworms, cockroaches, fly pupae, grasshoppers and crickets. We have found kangaroo mince most suitable especially for small dasyurids because they can easily choke on the sinews that are found in most other types of meat. While mixing the meat mix to a dryish consistency with your fingers, any fat, sinewy pieces or bones should be removed if it is prepared for planigales or ningauis. The dry dog food is put through a hammer mill and then stored in a dry place.

5 5A One of our largest carnivorous marsupials, the Spotted-tailed Quoli Dasyurus maculaws of eastern Australia is an opportunistic predator ttiat scavenges from carcasses and tiunts birds, rats, possums and insects. Photo: ft and A. Williams. 5B Ttie Yellov»-footed Antecfiinus Antechinus tiavipes, a medium-sized carnivorous marsupial, is one of ttie few small nocturnal marsupials still seen around suburban gardens and tiouses. Its diet is mainly insects but also includes mice and small birds. Photo: ft and A. Williams. 5C The 20 g Stripe-faced Dunnart Sminthopsis macroura, an inhabitant of inland central and northern Australia, is one of approximately 24 small Australian camivorous marsupials. Photo: ft and A. Williams. 5D - The Long-nosed Bandicoot Perameles nasula of eastern Australia is one of the three most commonly kept bandicoot species. It is probably best known for the conical holes it makes in suburban lawns when foraging for insects at night. Photo: ft and A. Williams

6 The meat must be kept frozen right up to the time of food preparation to prevent possible toxoplasmosis (Attwood and Woolley 1979), salmonellosis and infestation by other dangerous organisms. Prior to the practice of freezing, an unreliable supply of kangaroo meat caused an outbreak of enteritis in a colony of Dusky Antechinus Antechinus swainsonii. The meat mix was successfully replaced with the dog food Luv mince (Luv Pet Foods, NSW) with egg (Williams and Williams 1982). it is difficult to give exact amounts of food required per animal as this varies between individuals within a species and depends on the size, activity and breeding condition of the animal. By experimenting with amounts, and weighing the animals frequently, a correct feeding regime should soon be established. Overfeeding is undesirable and costly. Recently 1 have been using a balanced, small carnivore mix manufactured by Wombaroo Food Products* for Kowaris (Dasyuroides bymei) and Dusky Antechinus. The results have been promising. Although this mixture can be used on its own, 1 give freshly killed mice once a week and add, when available, a few mealworms to the mixture once or twice a week. This diet is slightly more expensive than the meat mix but has advantages. It is a balanced diet and the exact amounts to provide nutrition are easily calculated thus enabling minimal wastage. It is easy to prepare and the dry mix does not require refrigeration, it has a long shelf life of nine months if stored in a resealable airtight container. When feeding a colony of animals, extra food may be needed to ensure all animals have access to sufficient food. Large Species 7 The Tasmanian Devils and quolls are more carnivorous in their food tastes than the smaller, often insectivorous dasyurids. Chickens of varying ages and small mammals such as mice, rats, guinea pigs and rabbits are readily taken when available. The standard meat mix is also used on a regular basis. Feeding whole, disease-free birds and mammals to dasyurids appears to overcome the problems of rickets and other bone disorders associated with raw meat diets. Because obesity from overfeeding is common, the weights of these animals should be checked frequently and fasting days introduced if there is excessive weight gain. Obesity in these species can cause hair loss, lethargy and possibly poor breeding potential. BREEDING An intimate knowledge of the life cycle of some species is essential if successful breeding groups are to be maintained. Most dasyurid species are best kept singularly or in breeding pairs, unless large cages are provided. Pairing of animals may need to be rotated until a compatible pair is found. Dick Whitford (pers. comm.) has had great success breeding several dasyurid species by only introducing the male to the female when she is in oestrus. To determine if a female is in oestrus vaginal smears or urine can be examined under a microscope for the presence of cornified epithelial cells. In most species, oestrus is fairly short and daily testing is required. This may stress the animals and prevent breeding. Wombaroo Food Products, P.O. Box 151, Glen Osmond, SA 5064; Mew South Wales Agent Helen's Fauna Nursing Service, The Cedars, Moss Vale Road, Beaumont, MSW 2577.

7 Observation is an alternative to testing but is time consuming, if the animals are separated but have contact through a wire panel, behavioural changes can indicate when the female is coming into oestrus. Some species have also been observed to call each other when the female approaches oestrus (D. Whitford, pers. comm.; Whitford et al. 1982; Fox and Whitford 1982; Fanning 1982). Antechinus species are monoestrus and the breeding season within a population is the same each year, give or take a week or two. During mating, males can become very aggressive, especially with unco-operative mates and in captivity females can be scalped and killed. Some three weeks after mating the males die and disappear from the population. However, although showing initial signs of deterioration in captivity, the males can survive with a good supply of food and care. Males should be removed after mating. Species of Sminthopsis on the other hand are polyoestrus so may have more than one litter within a breeding season. The males also survive more than one breeding season. Given a large enough cage these species may be kept as a breeding group but if serious fighting occurs separation may be necessary. The larger dasyurid species, the Tasmanian Devil and quolls, are difficult to breed in captivity and a great deal of care and effort is required although 1 have seen some of these species breeding in what 1 would term sub-standard housing in private zoos. 72 Breeding season is during the winter months and although it extends over a few months the females are usually monoestrus so there may be problems synchronizing the male and female. Female Spotted-tailed Quolls call when coming into oestrus (D. Whitford, pers. comm.) so this can be used as a sign to introduce a male. It has been suggested that overweight animals do not attain successful breeding condition. HANDLING TECHNIQUES Large Dasyurid Species Large dasyurids have powerful jaws and should be handled with care. For cage transfer or cleaning it is convenient to have a sliding or hinged door on the nestbox so that the animal can be locked away. For examination purposes either catch the animal by the tail and lift the hind legs off the ground or catch with a bag net then transfer by the tail into a cloth bag. The animal can then be held by the back of the neck with one hand and the rump with the other. A second person can then peel back the bag to make the necessary observation. Small and Medium-sized Dasyurid Species Most of these species can be caught by an experienced person by quickly placing the flat of the hand over the animal then holding the base of the tail with the other hand. The body is then enclosed; care should be taken not to throttle the animal. All these animals bite but apart from the phascogales, Mulgaras (Dasycercus cristicauda) and Kowaris little or no damage is done to the handler. An alternative method is to catch the animal in an Elliott trap which can be emptied into a plastic or cloth bag. The animal can then be restrained with one hand around the body and the other holding the base of the tail. A second person is usually required to carry out measurements and so on. Because these animals are very agile it is wise to carry out these procedures in an escape-proof room.

8 PROBLEMS AND DISEASES As mentioned above, many problems arise from poor feeding. Obesity from overfeeding is a common occurrence in captive dasyurids. infections, usually fatal, caused by feeding contaminated meat and whole animals have resulted in outbreaks of toxoplasmosis (Attwood and Woolley 1979), enteritis (Williams and Williams 1982) and salmonellosis. Freezing the meat and using specific pathogen free (S.P.F.) animals usually avoids these problems. Tumors are common in dasyurids particularly in old animals. Ectoparasites are also common and include mites, ticks and fleas. Mange mites can be a problem especially in Tasmanian Devils and quolls. Ectoparasites can be controlled by pest strips. Small pieces of Shelltox pest strip are placed in small screw top jars with two or three small holes drilled in the top and these are placed in the cage. Great care should be taken because overexposure to Shelltox can be fatal; the jar should be removed periodically. Insect larvae of unknown identity were found buried in the skin of a Spotted-tailed Quoll. The animal became bald on the rump and close inspection revealed the larvae which were removed with forceps. Overcrowding, another common problem, results in tails, ears and other extremities being chewed off. REFERENCES ASUN, H. J., Small dasyurid marsupials: their maintenance and breeding in captivity. Pp in "The Management of Australian Mammals in Captivity" ed by D. D. Evans. Zoological Board of Victoria, Melbourne. ATTWOOD, H. D. AND WOOLLEY, P. A., Histopathoiogy of captive dasyurid marsupials. Pp in "The Management of Australian Mammals in Captivity" ed by D. D. Evans. Zoological Board of Victoria, Melbourne. FANNING, F. D., Reproduction, growth and development in Ningaui sp. (Dasyuridae, Marsupialia) from the Northern Territory. Pp in "Carnivorous Marsupials" ed by M. Archer. Royal Zoological Society of New South Wales, Sydney. Fox, B. J. AND WHITFORD, R., Polyoestry in a predictable coastal environment reproduction, growth and development in Sminthopsis murina (Dasyuridae, Marsupialia). Pp in "Camivorous Marsupials" ed by M. Archer. Royal Zoological Society of New South Wales, Sydney. MORTON, S. R., DICKMAN, C. R. AND FLETCHER, T. P., Dasyuridae. Pp in "Fauna of Australia. Vol. 1B. Mammalia" ed by D. W. Walton and B. J. Richardson. Australian Government Printing Service, Canberra. STRAHAN, R. (ed), "The Australian Museum Complete Book of Australian Mammals." Angus & Robertson, Sydney. VAN DYCK, S., The Chestnut Dunnart, Sminthopsis arc/jeri (Marsupialia, Dasyuridae), a new species from the savannahs of Papua New Guinea and Cape York Peninsula, Australia. Aust Mammal. 9: WNRTFORD, R., FANNING, F. D. AND WHITE, A W., Some information on reproduction, growth and development in Planigale gilesi (Dasyuridae, Marsupialia). Pp in "Camivorous Marsupials" ed by M. Archer. Royal Zoological Society of New South Wales, Sydney. WILLIAMS, R. AND WILLIAMS, A, The life cycle of Antechinus swainsonii (Dasyuridae, Marsupialia). Pp in "Camivorous Marsupials" ed by M. Archer. Royal Zoological Society of New South Wales, Sydney. WOOLLEY, P. A, Laboratory maintenance of dasyurid marsupials. Pp in "The Management of Australian Mammals in Captivity" ed by D. D. Evans. Zoological Board of Victoria, Melbourne. 73

9 74