Black oystercatchers are large, dark shorebirds with reddish bills that live along the coast from Alaska to Baja California. They are a Species of High Conservation Concern and understanding oystercatcher movements and habitat use throughout the year is a priority for the U.S. Fish and Wildlife Service. USGS and USFWS scientists collaborated in an international effort to assess range-wide movements using satellite and conventional transmitters. Results demonstrated medium- to long-distance migration in three breeding populations in Alaska and year-round residency in another Alaska site and in British Columbia. These and other findings provide important baseline information to monitor changes in habitat use due to climate change and human development.