|Habitat and Ecology:|
With males weighing 26-55 g (mean 36 g) and females 25-42 g (33 g), the Sandhill Dunnart is the second largest member of the genus Sminthopsis and marginally lies within the ‘critical weight range’ (Burbidge and McKenzie 1989); terrestrial mammals within that range have an elevated likelihood of extinction or significant decline, especially in arid areas.
Sandhill Dunnarts occupy sandy semi-arid and arid parts of southern and central Australia, often with sand dunes, where the vegetation is dominated by spinifex Triodia spp. hummock grassland. A study on Eyre Peninsula found Sandhill Dunnarts commonly nested in large spinifex hummocks that had started to die off in the centre. They entered these spinifex hummocks by leaping up onto the hummock and climbing over the needles to the centre before scrambling down through the central portion of dead leaves. In the centre of the hummock they built a circular depression or space within the dead spinifex needles. Adult female dunnarts occasionally dug burrows; starting from inside the spinifex the burrows spiral down under the plant. These burrows were up to 90 cm long and had a small terminal chamber that contained nesting material of leaves and shredded bark. Male Sandhill Dunnarts were found to use a greater variety of nest sites than females, including small burrows between spinifex clumps, hollow logs, and Mitchell’s Hopping-mouse Notomys mitchellii burrows (Churchill 2001). In the Great Victoria Desert, both sexes tend to build burrows, from 30 cm to 1 m long, under spinifex hummocks (Pearson and Churchill 2008). Sandhill Dunnarts have relatively large home ranges of up to 7.5 ha. They can move rapidly over long distances, with individuals being recorded moving up to 1,960 m in two hours (Pearson and Churchill 2008).
In Yellabinna Regional Reserve, monitoring between 2008 and 2012 demonstrated a tenuous relationship between spinifex height (but not cover, size or continuity) in an area of dunes where capture rates are seemingly higher than elsewhere in Yellabinna (with sparser parallel dunes) (Ward 2008). However, spinifex height has been comparable at other locations where capture rates are lower and in areas where no Sandhill Dunnarts were found in surveys. The area of jumbled dunes may coincide with appropriate topography or underlying hydrology that allows for greater productivity and food abundance (M. Ward pers. comm. 2014). Alternatively, the large area of continuous habitat and relatively thick spinifex cover may allow Sandhill Dunnarts to more effectively evade introduced predators.
Diet consists of a wide variety of small to medium-sized invertebrates, mainly ants, beetles, spiders, grasshoppers, wasps and centipedes (Pearson and Churchill 2008).
The species’ shelter behaviour, inside spinifex hummocks or in burrows, would limit predation by feral cats and red foxes; however, they would be prone to predation while foraging. Extensive, hot, summer fires, which are now common in the central spinifex deserts, are a significant threat as they destroy habitat over very large areas, limiting reinvasion as the vegetation recovers. Frequent fire is also a threat, as Sandhill Dunnarts require old spinifex hummocks in which to shelter. Future threats could include the spread of invasive Buffel Grass Cenchrus ciliaris which has replaced many grasslands further north and has recently invaded the Sandhill Dunnart’s range.
Sandhill Dunnarts appear to have a seasonal but extended breeding period and are able to reproduce from late winter to autumn (Lambert et al. 2011; A. McLean pers. comm. 2014). At the Middleback Range, Eyre Peninsula, South Australia, the breeding season commenced with mating in August, females with up to eight pouch young were observed in September/October and juveniles were observed dispersing in January (McLean et al. 2012).