Connectivity drives occupancy in Rocky Mountain amphibians
Brett R. Addis, Wendy Estes‐Zumpf, Gabriel M. Barrile, Melanie A. MurphyResolving the extent to which populations rely on connectivity for long‐term persistence is essential for guiding conservation strategies to address global biodiversity loss. Dispersal among habitat patches can promote long‐term persistence by facilitating colonization of unoccupied sites and reducing local extinction through demographic rescue. Dynamic occupancy models, particularly autologistic versions that account for spatiotemporal dependency, offer a powerful framework for quantifying these processes to understand the threat isolation poses to natural populations. We applied autologistic dynamic occupancy models to long‐term amphibian monitoring data from the Rocky Mountains (Wyoming and northern Colorado, USA) to assess the importance of spatial connectivity for six amphibian species and estimate temporal trends in occupancy that are essential for regional conservation planning. We found that species were more likely to colonize and persist at sites surrounded by a higher proportion of occupied wetlands, indicating that movement among connected wetlands plays a key role in maintaining site occupancy and reducing local extinction risk. Despite consistently low colonization probabilities, high persistence rates have led to stable or increasing occupancy for all but two amphibian species in our study. These results are encouraging given the high prevalence of chytridiomycosis – a disease linked to amphibian declines globally – across our study area, and suggest that the demographic benefits of movement among sites outweigh the potential negative effects of pathogen transmission. Our results also suggest that management efforts focused on preserving connectivity, rather than efforts focused solely on improving habitat quality, will be most beneficial for the long‐term viability of our study species.