Estimation of metademographic rates and landscape connectivity for a conservation-reliant anuran
Context Amphibian conservation efforts commonly assume populations are tied to waterbodies that collectively function as a metapopulation. This assumption is rarely evaluated, and there is a need to understand the degree of connectivity among patches to appropriately define, manage, and conserve biological populations.
Objectives Our objectives were to quantify local persistence, colonization, and recruitment (metademographic rates) in relation to habitat attributes, evaluate the influence of the spatial arrangement of patches on landscape-scale population dynamics, and estimate the scale at which metapopulation dynamics are occurring for the Oregon spotted frog (Rana pretiosa).
Methods We collected R. pretiosa detection/non-detection data and habitat information from 93 sites spread throughout the species’ core extant range in Oregon, USA, 2010–2018. We developed a spatial multistate dynamic occupancy model to analyze these data.
Results Results indicated the proportion of sites occupied by R. pretiosa was relatively stable despite regular turnover in site occupancy. Connectivity was highest when the distance between sites was within 4.49–7.70 km, and populations within 1 km are at the appropriate spatial scale for effective population management. Rana pretiosa metademographic rates were strongly tied to water availability, vegetation characteristics, and beaver dams.
Conclusions Our analysis provides critical information to identify the appropriate spatial scale for effective population management, estimates the distance at which populations are connected, and quantifies the effects of hypothesized threats to species at a landscape scale. We believe this type of model can inform conservation and management strategies for multiple species.