From the ground up: microhabitat use within a landscape context frames the spatiotemporal scale of settlement and vacancy dynamics in an endemic habitat specialist

Abstract

Understanding how species are distributed throughout landscapes requires knowledge of the hierarchy of habitat selection made by individuals, the resulting spatiotemporal structure of demography, and the consequent dynamics of localized populations. We examined how patterns of habitat use, settlement, and vacancy in an endemic habitat specialist, Sceloporus arenicolus (dunes sagebrush lizard), varied within the Mescalero Monahans Sandhills ecosystem. We used a 4-year mark-recapture dataset to develop occupancy models that identified whether microhabitat or landscape scale best predicted S. arenicolus spatiotemporal habitat use, settlement, and vacancy, in both an undisturbed and disturbed landscape. Our results showed areas of high quality habitat were used constantly and lower quality areas were used intermittently, but repeatedly, over time in the undisturbed landscape. Habitat use in the disturbed landscape was spatiotemporally unpredictable. Microhabitat variables characterizing dune landscape topography predicted probability of use in S. arenicolus, while landscape-scale variables predicted probabilities of settlement and vacancy. In the undisturbed landscape, future settlement was predicted by presence of S. arenicolus, a pattern consistent with fine-scale source-sink dynamics already described for this species. Our results illustrate how spatially-discrete but temporally-linked areas should be conserved at fine spatiotemporal scales to secure persistence of S. arenicolus populations under variable environmental conditions. Disturbances to habitat continuity can disrupt individual movements and create inconsistently occupied habitat patches that appear to be unoccupied and thus are threatened by further disturbances.