Digging deeper: habitat selection within the home ranges of a threatened marsupial

While resource selection varies according to the scale and context of study, gathering data representative of multiple scales and contexts can be challenging especially when a species is small, elusive, and threatened. We explore resource selection in a small, nocturnal, threatened species—the greater bilby (Macrotis lagotis)—to test (a) which resources best predict bilby occupancy, and (b) whether responses are sex-specific and/or vary over time. We tracked a total of 20 bilbies and examined within home range resource selection over multiple seasons in a large (110ha) fenced sanctuary in temperate Australia. We tested a set of plausible models for bilby resource selection, showing that food biomass (terrestrial and subterranean invertebrates, and subterranean plants) and soil textures (% sand, clay and silt) best predicted bilby resource selection for all sampling periods. Selection was also sex-specific; female resource use, relative to males, was more closely linked to the location of high-quality resources (sandier soils, and terrestrial invertebrate biomass). Bilby selection for roads was independent of season but varied over time with females selecting for areas closer to roads when plants increased in density off roads. Our findings demonstrate the importance of considering resource selection over multiple contexts and highlight a method to collect such data on a difficult to study, threatened species. Collecting such data is critical to understanding the habitat required by species.

Methods
Data includes terrestrial invertebrate, and subterranean invertebrate and plant biomass data collected over four seasons (summer 2020, winter 2020, spring 2020, and summer 2021). We have also provided the R code used for generating the interpolation rasters and the necessary shapefiles (generated in QGIS) and rasters for this interpolation. The R code used for construction of resource selection functions and for generating 'Figure 4' in the main paper is also provided. The GPS data associated with this analysis can be requested from the corresponding author upon reasonable request.