Ecology of the eastern quoll dasyurus viverrinus, (Dasyrudae: Marsupialia)

Abstract

The ecology of the eastern quoll Dasyurus viverrinus was studied in southern Tasmania from July 1978 to June 1981. Most of the research on population processes and social organization was conducted on a population in the Huon peninsula. Qualls had one breeding season each year. Although females were seasonally polyoestrous (May-August), the high synchrony of births indicated tl1a t females usually conceived on their first oestrus. Only one litter was reared each year due to the long period of growth (approximately two months in the pouch and two months in the den, June-October). Because females normally produced 5-6 young, large numbers of juveniles entered the population ~n early summer. Although many juveniles dispersed, the majority of the breeding adults during the following year were animals in their first breeding season. Few females bred beyond three years of age and reproductive success was reduced by this age. The life span of quolls in the wild was 3-4 years. Survival of adult males was reduced during or following the mating season and survival of females was reduced during the post-weaning period, when population density was greatest. Quolls were opportunistic predators of insects and small prey but consumed carrion and vegetable matter when it was available. Seasonal fluctuations in insect abundance and availability were reflected in the diet. Lepidopteran larvae were a major food item and were abundant during the period of late lactation, weaning and early juvenile independence. The average home range size for males was 44 ha and for females was 35 ha. Although home ranges overlapped extensively, residents tended to avoid the areas used intensively by their neighbours. 'Neighbourhoods ' formed throughout the study area based on the extent of home range overlap between residents. Large interindividual distances between neighbouring residents suggests that they avoid one another in their area of home range overlap. Quolls constructed underground dens of varying complexity, usually within woodland gullies. Although females occupied dens exclusively while rearing their young during July-October, generally males and females occupied many dens, which were used by other quells on other nights. Den sharing occurred occasionally, usually by pairs or groups of females. Although females which belonged to 'neighbourhoods', on the basis of home range overlap, tended to occupy the same dens, males within 'neighbourhoods' did not. Quolls in captivity exhibited little social behaviour. Males formed a dominance hierarchy which was maintained by avoidance and submissive behaviour of sub-ordinates following agonistic encounters with dominants . Aggressive behaviour and activity levels in males increased during the mating season. Females exhibited little aggressive behaviour until their young became too large to be carried in the pouch ; aggression was then primarily directed toward other breeding females. Androgen concentrations in males increased to a peak during the mating season. There was a concurrent increase in corticosteroid concentration in peripheral blood plasma but this did not exceed the maximum corticosteroid binding capacity. The greatest increase in corticosteroid concentration in both sexes occurred during summer when population density was greatest. In general, the quoll was a solitary, nocturnal predator of insects and small prey. Its diet appears to have been a major influence on the evolution of both its life history strategy and its social system . Show more