Context. Reptiles partition their activity among their microhabitats for thermoregulatory, predatory, and refuge opportunities. We investigated whether a habitat specialist, the endangered pygmy bluetongue (Tiliqua adelaidensis), preferentially occupied vacant spider burrows in specific microhabitats in agricultural grasslands.
Aims. We investigated whether (1) microhabitat availability influenced associations of lizards occupying burrows among four populations, (2) lizard microhabitat preferences varied over time and, (3) whether a correlation was present between lizard body condition and the occupancy of spider burrows in specific microhabitats.
Methods. We assessed the microhabitat surrounding pygmy bluetongue-occupied spider burrows and unoccupied burrows that fit the criteria to be potentially suitable for pygmy bluetongue occupancy among four populations over two field seasons. We used the presence or absence of a lizard within a spider burrow to generate models to assess the probability of lizard occupancy to test whether pygmy bluetongues exhibited microhabitat preferences when occupying a spider burrow.
Key results. We found that pygmy bluetongues were strongly positively associated with burrows on an angle and were negatively associated with burrows surrounded by bare ground, rock, lichen, and that were further from vegetation. Microhabitat preferences varied among populations and time, which may have been influenced by habitat availability at each site and season. We also found that pygmy bluetongue body condition was positively associated with greater rock cover; however, rock availability did not exceed 10% cover, which suggests that it may have been an incidental association owing to the low sample size of caught lizards or was affected by above-average rainfall.
Conclusions. Microhabitat preferences exhibited by habitat specialists such as the pygmy bluetongue may differ when inhabiting locations that differ in their availability of high-quality habitat.
Implications. Our results have implications for selecting appropriate microhabitats when installing artificial burrows for lizards at future translocation sites and land-management implications to ensure landscape heterogeneity of benefit for successful conservation.
