Southern Nevada has a long history of underground mining and hundreds of abandoned mines remain throughout the region. We have been surveying and actively monitoring bat use of roughly 350 abandoned mines throughout the region since 2006. Over that time, patterns of roost use have been stable with species composition and colony sizes remaining predicable over time. Beginning in 2021 and continuing through 2022 there has been a notable increase in species richness and intensity of use in these features. These changes correlate with drought and heightened surface temperatures throughout the region. Subterranean temperatures have remained consistent despite increased surface temperatures and our findings suggest that mine workings are providing refugia to species that have historically roosted in epigeic features that provide less buffer from changes in ambient conditions.