Dasyurids and the numbat
Dasyurids exhibit fairly typical carnivore digestive anatomy (Fig. 14.3) even though feeding strategies range from the highly specialised numbat (Myrmecobius fasciatus) (myrmecophagous) and omnivorous Antechinus and Phascogale spp.
to the more typically carnivorous quolls (Table 14.4). Lack of tooth wear reported in free-ranging numbats suggests they are of little use in mastication (Strait 2014). A long thin tongue and large salivary glands are adapted for myrmecophagy (Friend 1989). Numbats do not possess a caecum and have a glandular stomach most like mammalian carnivores (Friend 1989; Hogan et al. 2013). However, the BMR of the numbat is like other myrmecophages, and on average, half the standard BMR for eutherian mammals (Cooper and Withers 2002) (Table 14.2). This can be attributed to the low nutrient value of termites. Their BMR differs with season, and it has been suggested that in seasons of low food availability they will metabolise fat stores and BMR lowers to conserve energy (Cooper and Withers 2012). Dunnarts (Sminthopsis spp.) can also reduce metabolic rate through torpor if food is scarce or preferred feed items are not available (Munn et al. 2010).
Fig. 14.4. Comparative gastrointestinal anatomy of glider and possum species, progressing through different feeding strategies from minimal fibre-fermenting nectarivores on the left through to the facultative (brush-tailed possum [Trichosurus vulpecula]) and obligate folivores to the right. Images adapted from Hume (1999)
The chitinous exoskeleton of termites (5.1-16.5% chitin) is poorly broken down by numbats and is easily detected in faeces (Cooper and Withers 2004). It is unknown if chitinolytic bacteria are present in the microbiome of numbats and other myrmecophages and further investigation is warranted to determine their role in digestion (Delsuc et al.
2014). Spotted-tailed quolls (Dasy- urus masculatus) exhibit some seasonal variations in diet selection (Table 14.4). There are no sex differences although smaller size quolls (typically female) feed on smaller prey and feeding on more nutrient-dense mammals in winter coincides with breeding. Fat-tailed dun- narts (S. crassicaudata) balance food consumption to achieve the targeted intake of nutrients at which fitness is maximised. Dunnarts regulated consumption of all three macronutrients by selecting intakes with relatively low protein (23-32%), high lipid (49-61%) and low carbohydrate (13-19%) as a percentage of metabolisable energy intake (Wilder et al. 2016). This may also be the case for other dasyurids.Chong et al. (2020) describe the composition of the gut microbiome of the Tasmanian devil (Sarcophilus harrisii) and northern quoll (Dasyurus hallucatus), where these species’ adaptation to carnivory is evident in low abundance of phylum Bacteroidetes and high prevalence of phyla Firmicutes and Proteobacteria.
Captive diets for other dasyurids are described in Holz (2008). Seasonal variation to higher fat whole prey vertebrate items in species that consume these items naturally may help to encourage breeding. A further recommendation is to remove items such as dairy and high sugar fruit, to allow their natural regulatory mechanisms to balance intake and activity to maintain bodyweight as seen in dunnarts (Wilder et al. 2016).
9.