Feasibility Study on the Reintroduction of Beavers at Inspiration Ridge Preserve: Mitigating Climate Change Impacts to Peatlands on the Southern Kenai Peninsula

Abstract

The Center for Alaska Coastal Studies (CACS) tasked us with assessing if the current site conditions in the Inspiration Ridge Preserve (IRP), within the Fritz Creek watershed, are suitable as beaver habitat. With the disappearance of beavers from the Fritz Creek watershed and decreasing water availability on the Kenai peninsula over the past twenty years, peatlands and wetlands downstream of the site have dried significantly, putting stress on those systems and on the natural flora and fauna. Since beaver reintroductions have been successful in other systems to improve peatlands and wetlands undergoing significant desiccation (Simmons, 2015), CACS is suggesting the use of beavers as a restoration tool for the Fritz Creek watershed. CACS also expects that this project will jumpstart an initiative to reintroduce beavers to several historic sites within the Homer area. The main objectives of this report are i) to provide a recommendation to CACS regarding the feasibility of reintroducing the North American beaver (Castor canadensis) to the Fritz Creek watershed and ii) to recommend reintroduction methods and a monitoring plan to address the water quality concerns and carbon storage effectiveness of the peatlands in this location. To assess the feasibility of beaver reintroduction in the area, we conducted field surveys for a total of 21 observations along three reaches of the Fritz Creek stream to evaluate specific environmental parameters associated with suitable beaver habitat. We applied the Methow Beaver Project (MBP) Suitability Scorecard (2020 version) to estimate metrics of beaver habitat suitability and calculate a final suitability score for each observation and an average for each reach. The suitability scores range from 43 to 85, where a score above 45 indicates suitable habitat. Additionally, we assess the beaver dam capacity of the full stream length in the IRP using the Beaver Restoration Assessment Tool Capacity Inference System (BRAT-cIS) Form. The three reaches along the Fritz Creek we evaluated for release all received overall suitability scores above 45, indicating that they are suitable habitat for beaver reintroduction. The area is easily accessible and contains plenty of herbaceous food as well as woody food and trees that are appropriately sized dam building materials. The low streamflow and stream depth at our site poses one of the only major threats to beaver populations due to its inability to provide necessary cover and protection from predators. Our recommendation to CACS is to proceed with the plan to reintroduce beavers in the Fritz Creek watershed contingent on some modifications to improve the stream habitat. We strongly recommend the installation of at least three Beaver Dam Analogues (BDAs) in the stream to raise the water levels. Based on our research of beaver relocations and BDAs, we believe this will greatly increase the chances of successfully establishing a beaver population in the watershed and providing them with the means they will need to survive year round. Throughout this report, we provide additional strong recommendations, a monitoring plan, and resources to ensure a high chance of success in beaver reintroduction as a restoration strategy. Beyond the scope of this report is the assessment of extensive flooding and potential beaver migration to other locations, thorough habitat surveying and adjacent land ownership should also be considered when deciding the reintroduction.