Orben et al. (2025a)

Caspian Terns – Pacific Flyway Population Census 

The Seabird Oceanography Lab (Rachael Orben, Adam Peck-Richardson, Michael McGuire) completed the fourth assessment of the Pacific Flyway region Caspian Tern breeding population. In 2024, we conducted a comprehensive breeding population census by surveying every active and historical nesting location within the Pacific Flyway region. The need for a comprehensive census was motivated by growing concerns regarding previously documented population declines (Lawes et al. 2022) and by an outbreak of Highly Pathogenic Avian Influenza (HPAI) in Pacific Northwest Caspian terns in 2023, which resulted in a minimum observed mortality of 1,529 adults (Haman et al. 2024). The resulting regional breeding population estimates will be used to monitor the status of the Caspian Tern population in the Pacific Flyway region and allow for adaptive management practices for this population. This work was supported by U.S. Fish and Wildlife Service, Migratory Birds and Habitat Program (Portland, OR) and the many collaborators who shared observation data from Alaska to Baja California, Mexico.