Pacific Loon Home > Seabirds JP > Loons (Japan) > Pacific Loon Pacific Loon Gavia pacifica Common (mainly winter visitor) around Hokkaido, Honshu, Shikoku and Kyushu. Perhaps the largest number of population of Loons/Divers in Japan. Fig. 1. Adult summer. Fig. 2. Adult summer. Fig. 3. Adult summer. Same bird as Fig. 2. Fig. 4. Adult summer. Same bird as Fig. 2. Fig. 5. Presumed 1st winter. Fig. 6. Juvenile. Fig. 7. Migration birds. Fig. 8. Flock.