How beavers affect habitat availability for two native turtle species

Abstract Beavers’ ( Castor canadensis ) ability to dam streams and impound water into deeper pools may be enhancing habitat for turtles in urban settings, which could help reduce habitat degradation in these developed areas. Oregon, USA, is home to 2 native freshwater turtle species: the northwestern pond turtle ( Actinemys marmorata ) and the western painted turtle ( Chrysemys picta bellii ). Both species are experiencing declining populations in Oregon and are state conservation strategy species. The decline in these turtle populations predominantly results from human activities, such as urbanization. We assessed turtle habitat with field surveys and water temperature measurements to rank habitat at 7 beaver‐dammed and 7 control ponds in an urban area, Portland, Oregon. Beaver‐dammed sites had higher turtle habitat scores than did the control sites. Summer benthic water temperatures were colder at beaver‐dammed ponds and the difference between surface water and benthic water temperatures was greater in beaver‐dammed ponds than in control ponds. These findings suggest that beavers play a key role in creating and maintaining beneficial habitats for native turtles in Oregon, even in urban environments. In areas where beavers are absent, managers can replicate their ecological impacts to enhance turtle habitat. However, further research is needed to understand the extent to which beavers may be affecting thermal heterogeneity in beaver‐dammed ponds.