Project: Research, Monitoring and Evaluation of Avian Predation on Salmonid Smolts in Columbia River Plateau region
Client: USACE - Walla Walla District
Year: 2004 - 2013
Location: Columbia River PlateauProvided baseline information to assess the relative impacts of piscivorous colonial waterbirds on juvenile salmonid survival in the Columbia Plateau region. Information was used to develop an Inland Avian Predation Management Plan.
Native piscivorous colonial waterbirds that nest in the Columbia Plateau region include Caspian terns, double-crested cormorants, American white pelicans, California gulls, and ring-billed gulls. Of these, Caspian terns have been identified as the single most significant avian predator (per capita) in the Columbia Plateau region on salmonid smolts, particularly on ESA-listed steelhead populations from the Upper Columbia River and Snake River. The two largest Caspian tern colonies in the Columbia Plateau region were at Crescent Island on the mid-Columbia River and at Goose Island on Potholes Reservoir, WA. We observed a small number of banded Caspian terns that were originally banded as adults on East Sand Island in the Columbia River estuary, where management actions have been implemented, at the Goose Island and Crescent Island colonies, suggesting that there is connectivity between coastal and inland tern colonies.
In 2013, Caspian terns nesting at Goose Island were marked with GPS tags and tracked during foraging trips over several days. Nearly half of the GPS-tagged terns made foraging trips to the mid-Columbia River, including Wanapum Reservoir, Priest Rapids Reservoir, and Hanford Reach. Of note, four GPS-tagged terns made foraging trips to the lower Snake River, including one tern that exhibited the greatest foraging range ever documented in a breeding Caspian tern: 93 km straight-line distance from the colony.
Management of the Caspian tern colonies at Goose and Crescent islands to reduce their impacts on ESA-listed salmonids is currently underway. As part of a related study (see below), we assisted resources managers in the implementation and monitoring of the Inland Avian Predation Management Plan.
Project was conducted with Oregon State University and required close coordination and collaboration with the Corps, the U.S. Fish and Wildlife Service, Washington Department of Fish and Wildlife, and BOR.