Model transferability and predicted response of a dryland anuran to climate change in the Southwest United States

Aim: We propose a combined approach to explore the model transferability and the effect of climate change on habitat suitability. Location: Southwest United States. Taxon: Amphibians; Anura; Bufonidae; Anaxyrus microscaphus. Methods: To assess the impacts of climate change on A. microscaphus, we obtained 3162 records from the Arizona Game and Fish Department. We classified occurrence records data into six historical groups (from 1960 to 2018) and a contemporary group (from 2019 to 2022). We investigated the ability of historical data to generate accurate predictions of the species' contemporary distribution. We used species distribution modelling to compute habitat suitability values and identified spatial clusters of high suitability values (using hotspot analyses). Results: We show that historical occurrences successfully predicted the contemporary distribution of A. microscaphus. We demonstrate that the geographical distribution of contemporary hotspots is strongly related to precipitation of the wettest quarter. This research provides evidence that climate change will likely affect the distribution of hotspots and the habitat suitability of A. microscaphus. Losses of 37%–48% contraction are expected at the margins of the range both in the north and south of the geographic limits. Main Conclusions: We show that recent past data can be used to predict contemporary species distribution accurately. We highlight that habitat suitability values of A. microscaphus are strongly related to climate, topography and distance to streams. This study provides clear evidence of the negative impacts of climate change on habitat suitability in the Southwest United States drylands. Our approach has applied utility to managers to target survey areas, monitor habitat changes, plan for conservation mitigation measures, conserve stream flows across the species' range and inform recovery if needed. Thus, managers could use previously collected data to predict contemporary species distribution when their occurrence accurately characterizes the species' ecological niche.