Conservation of quolls (Dasyurus spp.) in captivity – a review

Quolls are carnivorous marsupials in the family Dasyuridae with characteristic white spots. They are distributed throughout Australia and New Guinea, but uncommonly seen due to their mostly nocturnal solitary nature, and large home ranges. All Australian quolls are listed as ‘near threatened’ or ‘endangered’ at state, national and international levels, largely due to human-induced threats. Threats include introduced predators, habitat loss through clearing and modifications including changed fire regimes, disease, human persecution, vehicle collisions and accidental or targeted poisoning by humans and cane toads (Rhinella marina). Conservation efforts that have focussed on reducing introduced predators, and minimising the impact of cane toads, have aided some translocations, hence species recovery in some local areas of Australia has occurred. Where species conservation has required captive breeding for translocation, successful captive management has been crucial. We summarise research conducted in captivity on aspects of birth and development, health and disease, and blood and nutrition parameters of quolls, and suggest future directions for research. Further research on captive and wild quoll populations will benefit future translocations, reintroductions and conservation through increased knowledge, improved maintenance and husbandry of captive colonies, and monitoring of wild populations.

Nutritional status and functional digestive histology of the carnivorous Tasmanian devil (Sarcophilus harrisii)

Tasmanian devils (Sarcophilus harrisii) are the largest carnivorous marsupial in Australia. Currently many animals are being held in captivity as a management procedure to combat Devil Facial Tumor Disease. Only one published study thus far has investigated nutrition in Tasmanian devils, determining their maintenance energy requirements and digestibility on a rodent diet. More information is needed on Tasmanian devil nutritional and gastrointestinal function to aid in their management. Our study aimed to investigate the current nutritional status of Tasmanian devils in a captive population and functional morphology and histology of their gastrointestinal tract. Animals were maintained on a diet of kangaroo, rabbit, quail and chicken wings and digestibility of these items by the devils was high (>85% for dry matter, protein and lipid). Kangaroo and rabbit were high protein diet items while the quail and chicken wings provided high lipid to the diet, and carbohydrates were minimal (≤3% energy). Maintenance energy requirements were determined to be 620kJkg^-0.75d^-1 with no significant difference between males and females. Opportunistic samples for gastrointestinal morphology were obtained from captive specimens. Tasmanian devils have a simple digestive tract similar to other dasyurid species. Both the morphology and histology of the gastrointestinal tract show specialization for a high protein carnivorous diet.

Digestibility of two diet items by captive eastern quolls (Dasyurus viverrinus)

The eastern quoll (Dasyurus viverrinus) is a carnivorous Australian marsupial that has undergone significant geographical range contraction since European settlement, and is extinct on the mainland. Nutrition is not well researched in captive eastern quolls, and captive diets often consist of commercial pet foods as opposed to raw meat or insect diets. Improving nutrition will enhance reproductive output and ensure suitable numbers of quolls are bred to be used in translocation programs. The present study analyzed the composition of kangaroo mince and chicken necks, and the digestibility of these items, in a captive environment. The quolls had high apparent total tract digestibility on the chicken neck and kangaroo mince treatments (DM 83-88%, GE 95-97%, protein 94-97%, and lipids 94-95%, respectively). The apparent total tract digestibility of DM, GE, and proteins was significantly higher (t14= 2.465, P < 0.05; t14= 2.489, P < 0.05; t14= 5.470, P < 0.01, respectively) on the kangaroo mince treatment compared with the chicken neck treatment. This study provides the first data on Cu (-18-37%), S (86-95%), and Zn (26-28%) apparent total tract digestibility in a Dasyurid. Data gathered during this study can be used to improve management practices for captive quolls, including diet formulation and mineral supplementation.

Digestibility of feeding regimes of the red-tailed phascogale (Phascogale calura) and the kultarr (Antechinomys laniger) in captivity

Digestibility was studied in the red-tailed phascogale (Phascogale calura) and the kultarr (Antechinomys laniger), small insectivorous/carnivorous marsupials, to determine their nutrient requirements in captivity. The marsupials were fed a range of insects, rat (Rattus rattus) and small carnivore food (Wombaroo). Digestibility experiments were conducted for a total of 12 days, which incorporated a five-day adjustment phase followed by a seven-day collection period. The apparent digestibility values for the phascogale and kultarr were above 81% for dry matter, energy, protein and lipids on all diets provided. No significant difference was found between phascogales and kultarrs on the same diet with respect to apparent digestibility of dry matter, energy, protein and lipids. The apparent absorption of minerals varied for each diet for the phascogale and kultarr. Maintenance energy requirements were determined to be 954 kJ kg0.75 day–1 for the red-tailed phascogale and 695 kJ kg0.75 day–1 for the kultarr. Presented here are the most comprehensive data on diet digestibility for dasyurids thus far.

Rate of passage through the digestive tract of the kultarr (Antechinomys laniger)

The kultarr (Antechinomys laniger) is a small insectivorous marsupial that has undergone significant declines in geographical range. Limited studies have been undertaken on kultarr biology and therefore there is a lack of understanding of its basic biological and ecological requirements. Rate of passage in the kultarr, determined using mealworm cuticle as a marker in minced beef, was 1.6 ± 0.2 h and mean retention time was 3.9 ± 1.2 h. The rapid transit time was consistent for an animal of equivalent body mass, dietary preference and gastrointestinal tract morphology. Mean retention time was short, similar to that of other mammals with a small body mass. This study provides the first insight into gastrointestinal physiology of the little known kultarr.

Effect of available surface water on levels of antidiuretic hormone (lysine vasopressin) and water and electrolyte metabolism of the Rottnest Island quokka (Setonix brachyurus)

A sensitive radioimmunoassay was developed to measure circulating levels of the neurohypophysial peptide lysine vasopressin (LVP) in the marsupial quokka (Setonix brachyurus), which is abundant on Rottnest Island off the coast of Western Australia. Animals from locations on the island where free water is completely absent were compared in midsummer with animals from sites where brackish water is available and utilized by the quokkas. In the animals from West End, where free water is absent, circulating levels of LVP averaged 89.2 +/- 19.6 pg/ml, which was significantly higher than the mean level of 35.6 +/- 15.8 pg/ml measured in individuals collected from the Lakes site with access to brackish drinking water. Rates of water and sodium turnover, measured with isotopes, were significantly greater in Lakes than West End animals, as were renal clearances of sodium, chloride, urea, and total osmolytes. Despite an obvious osmotic diuresis resulting from the ingestion of salty water, the Lakes animals were in better physical condition at the end of summer than the West End animals which lack free water, and these latter individuals showed signs of slight dehydration with elevated plasma and urinary electrolyte concentrations and osmolalities.

Intake of milk by suckling echidnas (Tachyglossus aculeatus)

Estimation of milk intake in the sucklings of three captive echnidnas, Tachyglossus aculeatus, and in one living in its natural habitat were made by determination of sodium turnover rate and sodium content of the milk. The mean rate of sodium influx of the sucklings was 2.48 +/- 1.31 mmol/kg X day. The daily rates of milk consumption and growth rates were variable with a mean weight increment of 0.41 +/- 0.10 g for each ml of milk consumed. There is a wide disparity in growth rates of echidna young that is related to differences in the body weights of the mothers.