Range extension for the gray-backed tern in the western Pacific

About 75 pairs of Gray-backed Terns (Sterna lunata) nested on Guguan in the Northern Mariana Islands in 1979. This locality represents a breeding range extension of about 2000 km to the west of the westernmost previously known colony. The species is also reported for the first time from Uracas, northernmost of the Northern Mariana Islands, where it may also breed.