Population dynamics of dasyurid marsupials in dryland Australia: Variation across habitat and time

Abstract The irruptive population dynamics of rodents are a globally renowned wildlife phenomenon; however, the dynamics of other small mammals with which rodents are sympatric are poorly understood. Dryland Australia supports a high diversity of small (<200 g) arthropod‐eating marsupials (Dasyuridae). Here, we test the hypothesis that dasyurid marsupials do not exhibit the same degree of irruptive population dynamics that are shown by rodents. We addressed this question by sampling small mammal assemblages on 20 permanent trapping sites in the Simpson Desert on 20 occasions from 2007 to 2017. Sampling was stratified across three broad habitat types: sandridge, gibber plain and clay plain. We captured 478 dasyurid marsupials of nine species, ranging in mean body mass from 5.75 to 93.50 g, at a capture rate of 1.71 per 100 trap‐nights. Capture rate varied across habitat and over time and the interaction between these two effects was also significant. Capture rate was highest on clay plain (3.35 captures/100 trap‐nights), followed by gibber plain (2.16 captures/100 trap‐nights) and lowest on sand habitat (0.54 captures/100 trap‐nights). Each species had a clear preference for one of the dominant habitat types. Dasyurid assemblages responded to high rainfall pulses in November–December 2008 and January 2015; however, the largest rainfall period in 2010–2011 resulted in very low captures. Likewise, a peak in abundance occurred in April 2008 although it was not preceded by high rainfall. We conclude that, although dasyurid marsupial capture rates varied up to 34 fold during the study period, population changes are not strongly tied to rainfall. Heterothermic physiology in this family, in particular the ability to use daily torpor to save energy, may be central to the decoupling of population dynamics from rainfall‐driven primary productivity.