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The black-tailed dusky antechinus (Antechinus arktos) is an endangered, small carnivorous marsupial endemic to Australia, which occurs at low population density along with abundant sympatric populations of other small mammals: Antechinus stuartii, Rattus fuscipes and Melomys cervinipes. Using A. arktos as a model species, we aimed to evaluate the effectiveness of infrared digital camera traps for detecting and differentiating small mammals and to comment on the broad applicability of this methodology. We also sought to understand how the detection probabilities of our target species varied over time and characterize their activity patterns. We installed 11 infrared cameras at one of only three known sites where A. arktos occurs for five consecutive deployments. Cameras were fixed to wooden stakes and oriented vertically, 35 cm above ground, directly facing bait containers. Using this method, we successfully recorded and identified individuals from all four species of small mammal known previously in the area from live trapping, including A. arktos. This validates the effectiveness of the infrared camera type and orientation for small mammal studies. Periods of activity for all species were highly coincident, showing a strong peak in activity during the same two-hour period immediately following sunset. A. arktos, A. stuartii and M. cervinipes also displayed a strong negative linear relationship between detection probability and days since deployment. This is an important finding for camera trapping generally, indicating that routine camera deployment lengths (of one-to-two weeks) between baiting events may be too long when targeting some small mammals.

The endangered black-tailed dusky antechinus (Antechinus arktos) was described in 2014, so most aspects of its ecology are unknown. We examined diet composition and prey selection of A. arktos and a sympatric congener, the northern form of A. stuartii, at two sites in Springbrook National Park. Overall, taxa from 25 invertebrate orders were identified in the diets from 252 scat samples. Dietary components were similar for each species, but A. arktos consumed a higher frequency and volume of dipteran larvae and Diplopoda, while A. stuartii consumed more Coleoptera, Lepidoptera, Orthoptera and Isopoda. Both species of Antechinus had a higher percentage of ‘empty’ scats (devoid of any identifiable invertebrate material) in 2014 compared with 2015. The former was a drier year overall. Lower rainfall may have reduced abundance and diversity of arthropod prey, causing both species to supplement their diet with soft-bodied prey items such as earthworms, which are rarely detected in scats. Comparison of prey in scats with invertebrate captures from pitfall traps showed both species to be dietary generalists, despite exhibiting distinct preference and avoidance of certain prey categories. The ability of an endangered generalist marsupial to switch prey may be particularly advantageous considering the anticipated effects of climate change on Gondwanan rainforests during the mid-late 21st century.

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