Project: Implementation and Evaluation of the Inland Avian Predation Management Plan
Client: USACE - Walla Walla District, U.S. Bureau of Reclamation, & Grant County PUD
Year: 2014 - 2019
Location: Columbia River Plateau
Provided assistance to the Corps and the Bureau of Reclamation in the implementation of Phase 1 and 2 of the Inland Avian Predation Management Plan (IAPMP). Included implementation of passive and active measures to prevent Caspian terns from nesting on Goose Island in Potholes Reservoir and Crescent Island on the mid-Columbia River. In addition, we assessed the outcome of management both in reducing the number of terns nesting in the Columbia Plateau region as well as reducing their impacts on juvenile salmonid survival.
The primary objectives of this study were to (1) implement components of the IAPMP, including adaptive management actions, in order to dissuade Caspian terns from nesting on Goose and Crescent islands (2) monitor the efficacy of those management components and actions at both the colony- and system-level, (3) measure the inter-colony movements of previously color-banded Caspian terns, and (4) model the change in predation rates on juvenile salmonids by Caspian terns in the Columbia Plateau region concomitant with management actions implemented as part of the IAPMP.
Management efforts implemented on Crescent and Goose islands were successful in eliminating and greatly reducing the number of terns nesting at each site, respectively. The estimated total population of Caspian terns nesting in the Columbia Plateau region in 2014-2016 was lower than the average population observed prior to management (2000-2013). Although Caspian tern management actions implemented in 2014-2016 were successful in reducing predation rates to less than 2% on most, but not all, ESA-listed salmonid populations, this benefit was largely offset by the increased predation rates by Caspian terns nesting at the other colonies in the region, in particular the colony at the Blalock Islands.
Project was conducted with Oregon State University and required close coordination and collaboration with the Corps and BOR, as well as multiple Federal, State, and Tribal stakeholders.