With the publication of the fourth edition of the AOU Check-list (AOU 1931), the Pacific Loon, Gavia pacifica, was submerged as a subspecies of the Arctic Loon, Gavia arctica. For the next 54 years little attention was given to distinction of the two in the field. In 1985, G. arctica and G. pacifica were again recognized as separate species with the publication of the sixth edition of the AOU Checklist (AOU 1983). Hence the recent upsurge of interest in G. arctica.