07/21/2026
Beaver build dams in river systems that cause extensive changes in ecosystem structure and processes, but a recent SRSC paper published in PLoS One shows that beaver can also be found in low-salinity tidal wetlands. This paper describes their widespread presence in tidal river deltas and estuaries of the Pacific Northwest (coastal British Columbia, Washington, and Oregon), where tides can range between 1.5 and 5.0 m. These observations expand the known habitat distribution of beaver and invite investigation of the ecosystem consequences of beaver in tidal wetlands. Tidal channel profile surveys with real-time kinematic (RTK)-GPS show that beaver dams there are typically flooded on higher high tides, only impounding water at low tide to allow beaver movement during this time. Tidal beaver dam density per km was more than twice that reported in the riverine literature, which suggests their role in tidal ecosystems may be just as significant as in rivers. Inspection of Google Earth aerial photographs back to 1990 indicated that tidal beaver dams can persist for at least 35 years, spanning several generations of beaver. Given the ecosystem importance of beaver in rivers, better understanding of the distribution and ecosystem role of beaver in tidal wetland habitat, would likely allow more effective restoration of estuarine habitat that is critical to a variety of fish and wildlife, including threatened species such as Chinook and coho salmon.
Beavers are well-known residents of rivers, lakes and streams across North America. New research finds they are also far more common in estuaries and tidal wetlands than was previously understood. The study suggests the rodents are critical ecosystem engineers in a habitat where twice-daily tides ra...
