Climate relict vulnerable to extinction from multiple climate-driven threats

Aim Over the gradually warming Holocene, many species' range limits shifted poleward. However, some populations persisted in climate refugia, such as mountain tops. These climate relict populations are critical components of regional biodiversity, but their isolation renders them vulnerable to other threats, including changes in environmental conditions indirectly related to a warming global climate. We aimed to quantify the role of these indirect climate effects on Florida saltmarsh vole (Microtus pennsylvannicus dukecampbelli; hereafter: "vole"), a poorly understood, endangered climate relict. Location The Gulf of Mexico between Sopchoppy and Pine Island, Florida, USA. Methods We surveyed for voles broadly across their potential range using camera traps and modelled the relationships between vole occurrence and two climate-driven threats: hurricane storm surge and shifting vegetation communities. We quantified these threats using both field-collected and remotely sensed data at fine (3-m) and coarse (150-m) spatial scales. Results Though seemingly suitable habitat exists outside their previously known range, voles appeared restricted to the outer marshes between the Suwannee and Withlacoochee Rivers. Within this range, the sites we surveyed had shorter grass heights, greater Distichils spp. cover, greater potential habitat within 150 m, and were less vulnerable to inundation when compared to sites outside of their range. Main conclusions The complex and varied ways in which climate change alters the physical environment can expose small-ranging species to multiple threats. Even climate relicts, which have endured historical changes in the global climate, may fail to cope with the rapid pace of anthropogenic climate change.