Heavy livestock grazing negatively impacts a marsupial ecosystem engineer

Ecosystem engineers play an important role in resource availability and can be negatively impacted by anthropogenic disturbances, such as livestock grazing. The decline of digging and burrowing mammals in Australia is partly attributed to agriculture, however little is known about their use of microhabitats, and thus, how they respond to different cattle grazing regimes. Here, we examine the response of a marsupial ecosystem engineer, the rufous bettong (Aepyprymnus rufescens) to cattle grazing strategies and vegetation types, and examine whether microhabitat selection is driving this response. We hypothesized that rufous bettongs would be negatively impacted by heavy cattle grazing due to their use of ground-level microhabitat features. We conducted a mark-recapture trapping survey among four grazing treatments and in two vegetation types (box and ironbark woodlands), at a 20-year grazing trial in northern Australia. We modelled rufous bettong abundance in response to grazing treatment and vegetation type and determined microhabitat preference using Manly selection ratios. We found that rufous bettongs preferred ironbark and avoided heavy grazing. Thus, they avoided the areas of highest cattle utilization. On average, individuals preferred high grass and other terrestrial microhabitat variables of moderate complexity. Our results indicate that habitat selection is contributing to the response of a marsupial ecosystem engineer to different grazing strategies. Mammalian digging and burrowing ecosystem engineers should be a conservation focus on rangelands due to their positive influence on a suite of species, and their ability to potentially mitigate some of the negative impacts of cattle grazing on soil health.