Factors affecting microhabitat use in two agamid species from south-eastern Australia

Abstract

Despite being a central aspect of a species' ecology and having important conservation implications, the use of fine-scale habitat features (microhabitats), and how they vary over time, are poorly known for most species. In this study, we leveraged 522 relocations of radio-tracked mallee tree dragons (Amphibolurus norrisi) and painted dragons (Ctenophorus pictus) to investigate the effect of environmental and individual variables on microhabitat use. Mallee tree dragons were more likely to use trees on hot days and in the middle of the day (the hottest time of day), whereas shrub use was more likely on cool days and in the mornings. Painted dragons were more likely to use shrubs and grass trees on warmer days and during the middle of the day, whereas burrows were used during cooler days and in the mornings and afternoons. We expect these patterns represent animals moving from refuge resources, occupied during unsuitable thermal conditions, to microhabitats offering basking, foraging and social opportunities during periods of thermal optimum. Additionally, we found evidence of an ontogenetic shift, with larger mallee tree dragons favouring tree use and higher perches, suggesting a transition from shrub to tree use with age. Our findings underscore the need for diverse microhabitats to accommodate the thermoregulatory and ontogenetic requirements of lizards. These insights can inform conservation and habitat restoration efforts, ensuring the provision of essential microhabitats to support species persistence.