Ecology and physiology of the northern quoll, Dasyurus hallucatus (Marsupialia, Dasyuridae), at Mitchell Plateau, Kimberley, Western Australia

Abstract

With 1 plate and 4 figures in the text) Breeding, population dynamics and seasonal changes in physical and physiological parameters were examined in the northern quoll (Dasyurus hallticatus) at Mitchell Plateau, Western Australia, between September 1981 and November 1982. Females gave birth to a single litter of young in July or August. Births were earlier on near-coastal sites than on inland sites. Litter size was greater on inland sites and litter size differed between years. By September all females were either carrying pouch young or were lactating. Lactation ceased by April. Testosterone levels in males peaked in July. There were significantly more male than female pouch young. However, in only one grid was the adult sex ratio different from parity, with an excess of females in September 1981 and 1982. Embryonic mortality was > 53% but loss of pouch young was small. Although males and females moved similar distances between successive recaptures, the extent of movement varied seasonally, being greatest in September. Males were generally larger and heavier than females. Seasonal variations were recorded for most physical and physiological parameters. The most pronounced changes occurred towards the end of the dry season (July to September) for both males and females. Over this period there was a significant decline in weight (males), haematocrit (males), plasma albumin (males) and leucocytes (both males and females) and significant elevations in values of haemoglobin and both free and protein-bound cortisol in both males and females. Few males survived the post-mating period from July to September. They appeared to decline in condition over this period more markedly than females: they lost more weight, their haematocrit and plasma albumin values declined to a greater extent, and they were more heavily infected with lice (Boopia uncinata). Males with lower testosterone and higher free and protein-bound cortisol had increased prospects of surviving the breeding season, which suggests that it is the dominant males that are less likely to survive the breeding season. Individuals in the three major populations at Mitchell Plateau differed greatly in their physiological values. The high-density population in a sandstone area had intermediate levels of free cortisol and higher haematocrit values than both the other populations, and higher levels of haemogl3bin than the population on laterite substratum.

Ecology and predator associations of the northern quoll (Dasyurus hallucatus) in the Pilbara

“…Northern quolls used to be distributed in most terrestrial habitat types in northern Australia, including savannah grasslands, closed and open forests, riparian forests, rocky habitats, mangroves, near sugarcane farms, in urban areas, and even in mining areas (Braithwaite and Griffiths 1994;Cramer et al 2016;Oakwood et al 2016;Pollock 1999). However, quolls have disappeared from most of these in recent decades and now favour rocky habitats , where their populations have higher densities than in neighbouring habitats, such as savannah grasslands, woodlands, and vine thickets (Braithwaite and Griffiths 1994;Schmitt et al 1989). Species habitat preferences can be altered depending on the level of perceived risk, including from larger predators.…”

“…Although northern quolls seem to be habitat generalists (Pollock 1999), their decline has been more severe in lowland savanna Oakwood 2002;Oakwood and Pritchard 1999), where local extinctions have been reported (Oakwood and Spratt 2000). Conversely, populations are reported at higher densities in rocky habitats, compared to savanna, forest, and vine thickets (Begg 1981b;Bradley et al 1987;Hill and Ward 2010;Schmitt et al 1989). This suggests that rocky habitats may serve as refuges against fire or introduced predators, or that their higher habitat complexity may allow higher prey availability .…”

“…Mating occurs over 2-3 weeks. Between 11 and 17 young are born, which usually translates to the successful attachment of young to all available teats (Nelson and Gemmell 2003); northern quolls have between six and 10 teats, but generally eight (Begg 1981b;Braithwaite and Griffiths 1994;Nelson and Gemmell 2003;Schmitt et al 1989). …”

“…The size of northern quolls also varies between regions. For example, quolls are larger in the wetter area of Kakadu National Park in the Northern territory (M = 761 ± 19.5 g, first year F = 448 ± 29.9 g, on average using data collected over three years on a three month period from April to June) (Oakwood 1997) than at the Mitchell Plateau, a drier area located in Kimberley region of Western Australia (M = 638.3 ± 127.0 g, F = 383 ± 60.6 g on average in July 1982) (Schmitt et al 1989). …”

“…Variation in reproduction times among populations can also occur in the same region. For example, Schmitt et al (1989) reported that populations closer to the coast reproduced three to four weeks earlier than inland populations in the Mitchell Plateau.…”