Sandbach, C. J.K. Young, M.M. Conner, E. Hansen, and P. Budy. 2024. Beaver Dam Analogues did not Improve Translocation Outcomes in a Desert River. Restoration Ecology. doi: 10.1111/rec.14107. USGS FSP IP-155481, BOA Date: November 7, 2023.
Abstract
Stream restoration programs employ beaver-related restoration techniques, including beaver translocations and installation of beaver dam analogs (BDAs), to create complex in-stream habitat. Our goal was to investigate whether BDA installations improved the probability of translocated beavers surviving and colonizing a section of degraded desert river. We translocated beavers fitted with VHF and/or PIT tags to the Price River in east-central Utah, for two years before and after BDAs were installed. We monitored survival and site fidelity of VHF-tagged beavers across all four years to estimate apparent survival, using model selection to evaluate models with BDA, flow, and other factors hypothesized to be related to apparent survival. We found similar apparent survival (φ) eight weeks post-release of pre-BDA beavers (φ = 0.50 ± 0.08 SE) and post-BDA beavers (φ = 0.41 ± 0.06 SE). Fifteen predation-caused mortalities occurred, and 43 beavers emigrated outside of the study site. Top models indicated apparent survival was negatively related to mean flow. Of the 70 BDAs that were constructed, we observed signs of beaver activity on two structures and the number of intact natural dams decreased due to monsoon floods. Our results suggest BDAs may not improve survival or site fidelity of translocated beavers in desert river systems. However, the negative relationship between flow and apparent survival suggests survival or fidelity may be improved if beaver translocations are timed to avoid high-flow events. Additional research is needed to understand how habitat, individual behavior, and resident conspecifics influence beaver translocation success.