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

Abstract

The northern quoll (Dasyurus hallucatus) is an endangered carnivorous marsupial in the family Dasyuridae that occurs in the northern third of Australia. It has declined throughout its range, especially in open, lowland habitats. This led to the hypothesis that rocky outcrops where it persists provide a safe haven from introduced predators and provide greater microhabitat heterogeneity associated with higher prey availability.Proposed causes of decline include introduced cane toads (Rhinella marina, which are toxic), predation by feral cats (Felis catus), foxes (Vulpes vulpes), and the dingo (Canis lupus), and habitat alteration by changes in fire regimes. The National Recovery Plan highlighted knowledge gaps relevant to the conservation of the northern quoll. These include assembling data on ecology and population status, determining factors in survival, especially introduced predators, selecting areas that can be used as refuges, and identifying and securing key populations. The Pilbara region in Western Australia is a key population currently free of invasive cane toads (a major threat).The Pilbara is a semi-arid to arid area subject to cyclones between December and ). These are dominated by spinifex (hummock) grasslands, with rugged rock outcrops, shrublands, riparian areas, and some soft (tussock) grasslands. They are subject to frequent seasonal fires, creating a mosaic of recently burnt and longer unburnt areas. The overall aim of this study was to assess the ecology of the northern quoll in the Pilbara to understand drivers of density and distribution of this endangered species, to enhance species-specific conservation efforts. I collected field data on six one-month trips over three years, predominantly using live-trapping, camera-trapping, sampling invertebrates, vegetation surveys, habitat structure, and den availability surveys.In the Pilbara, the largest mammalian predators are the introduced dingo and feral cat. The largest native mammalian carnivore is the northern quoll, which is smaller than the introduced predators but larger than the other dasyurids in the guild. In Chapter 2, I explored spatial and temporal associations among introduced predators and quolls and their associations with habitat to assess the impact of introduced predators on quolls. I found evidence that dingo control programs prevent dingoes from fulfilling their role as top predators, leading to mesopredator release of feral cats. Feral cats were associated with 3 open habitats (spinifex grasslands and recently burnt areas), and showed inverse associations to those of quolls, suggesting that quolls avoid cats in space. Quolls were positively associated with rocky habitats. In Chapter 3, I assessed spatial and temporal associations among dasyurids to understand the current role of northern quolls within their guild. I found that range contraction of northern quolls into rocky habitats prevent them from fulfilling their role as top predators across the landscape, potentially leading to mesopredator release of kalutas (Da...

Topographic ruggedness and rainfall mediate geographic range contraction of a threatened marsupial predator

“…Consistent with predictions, the largest absolute and proportional declines occurred in Queensland (areal reduction of 405,533 km 2 , 75.4% of the historic range), followed by the Northern Territory (115,024 km 2 , 57.7%) and the Kimberley (25,986 km 2 , 16.9%; Studies suggest quality northern quoll habitat is often associated with rocky rugged areas (Braithwaite & Griffiths, 1994;Burnett, 1997;Hernandez-Satin, 2016;Schmitt et al, 1989) Calculated according to Riley (1999) Geoscience Australia ( 2018 Increased productivity as a result of high annual precipitation may boost the capacity of northern quolls to tolerate threats (Burnett, 1997;Hohnen et al, 2016;McKenzie et al, 2007) WorldClim ( 2019)…”

“…The increase in ruggedness within the Queensland contemporary range likely reflects the loss of populations that previously occupied highly flammable, topographically simple landscapes, thought to have been more exposed to the threats of livestock grazing, altered fire regimes (more frequent and intense fires) and invasive predators (Hernandez-Satin, 2016;Oakwood, 2000). Similarly, central rock rats (Zyzomys pedunculatus) have contracted from more simple to more complex rugged habitat where the impact of their primary threat, the feral cat, is reduced (McDonald, Stewart, & Dickman, 2018).…”

Topographic ruggedness and rainfall mediate geographic range contraction of a threatened marsupial predator

“…We found support for this hypothesis in all populations other than the Pilbara, with the greatest increase observed in the Queensland population. The increase in ruggedness within the Queensland contemporary range likely reflects the loss of populations that previously occupied highly flammable, topographically simple landscapes, thought to have been more exposed to the threats of livestock grazing, altered fire regimes (more frequent and intense fires) and invasive predators (Hernandez‐Satin, ; Oakwood, ). Similarly, central rock rats ( Zyzomys pedunculatus ) have contracted from more simple to more complex rugged habitat where the impact of their primary threat, the feral cat, is reduced (McDonald, Stewart, & Dickman, ).…”

“…While including threats as predictors would likely aid in determination of their relative influence in shaping the northern quoll's contemporary range and niche, the scale and resolution of spatial layers required for this analysis do not currently exist and creating them was beyond the scope of our study. It may be possible to explicitly test the effect of threats on quoll populations in future studies by limiting the scale of analysis to a regional level and linking changes in northern quoll occupancy with threat distributions (Hernandez‐Satin, ). For example, by measuring declines in range and niche in relation to fire, it may be possible to elucidate the value of logs and tree hollows—important refuge features for many northern boreal and arboreal mammal species (Goldingay, )—as quoll habitat.…”

“…The total historic database consisted of 2025 historic records and 1,153 contemporary records (Appendix S1 Topographical ruggedness Calculated from the difference in elevation between a cell and the eight cells surrounding it (following Riley, 1999) Studies suggest quality northern quoll habitat is often associated with rocky rugged areas (Braithwaite & Griffiths, 1994;Burnett, 1997;Hernandez-Satin, 2016;Schmitt et al, 1989) Calculated according to Riley (1999) Geoscience Australia (2018)…”