Review of Caspian Tern (Sterna caspia) Nesting Habitat: A Feasibility Assessment of Management Opportunities in the U.S. Fish and Wildlife Service Pacific Region

摘要

This report is one part of a comprehensive effort to seek solutions to the issue of Caspian tern predation on listed salmonid smolts in the Columbia River estuary. Through interagency coordination and a formal mediation process sanctioned by the Ninth Circuit Court of Appeals (April 2002), Federal and State agencies, and nongovermental organizations agreed to explore options for restoring, creating, and enhancing nesting habitat for Caspian terns throughout portions of the Pacific Coast/Western region as one means to reduce and disperse the large tern colony on East Sand Island in the Columbia River estuary. The benefits of this action would be to reduce the level of tern predation on out-migrating Columbia River smolts and also lower the vulnerability of a significant portion of the breeding Caspian terns in the Pacific Coast/Western region to catastrophic events such as disease, oil spills, or storm events. The objective of this Feasibility Assessment is to evaluate a broad array of sites throughout Washington, Oregon, California, Idaho, and Nevada to determine management opportunities for the creation, enhancement or expansion of Caspian tern nesting sites based on biological features only. Sites were considered to have management potential for Caspian tern habitat if suitable habitat was present (or easily achievable through manipulation), relatively stable, and in close proximity to prey resources.