Common around Bonin Is and Volcano Is. Also few birds seen S Izu Is in summer, and E Honshu; off Choshi, Chiba Pref regularly Jun-Jul. Some Field Guides describe distribution including N Japan; around N Honshu and Hokkaido in summer. However, I think that it not be accurate because not seen regularly around these area except after typhoon passed. Breeding sites are confirmed on Bonin Is and Volcano Is.
Fig. 1. Off Chichijima, Bonin Islands, Tokyo. Sep 22 2020.
Fig. 2. Same bird as Fig. 1. Off Chichijima, Bonin Islands, Tokyo. Sep 22 2020.
Fig. 3. Off Chichijima, Bonin Islands, Tokyo. 6 Sep. 2022.
Fig. 4. Off Chichijima, Bonin Islands, Tokyo. 6 Sep. 2022.
Fig. 5. Off Chichijima, Bonin Islands, Tokyo. Sep. 11 2012.
Fig. 6. Presumed Adult. Off Kita-iwo-jima. Jul. 5 2013.
Fig. 7. Same bird as Fig. 6.
Fig. 8. Molting birds often lack ‘Bonin Mark’ (black under primary coverts). Adult birds molting start in summer; Jul-Aug, Off Muko-jima. Jul. 4 2013.
Fig. 9. Worn birds often indistinct darker head and ‘M’ pattern on upper wings. Off Iwo-jima. Jul. 5.2013.
Fig. 10. Presumed Adult.
Fig. 11. Presumed Adult. Same bird as Fig. 10.
Fig. 12. Presumed Adult. Same bird as Fig. 10.
Fig. 13. Presumed Adult. May be misidentified Black-winged Petrel.
Fig. 14.
Fig. 15. Same bird as Fig. 14.
Fig. 16. Same bird as Fig. 14.
Fig. 17. Flesh plumage shows Juvenile or flesh Adult.
Fig. 18. Off Mukojima, Bonin Islands, Tokyo. Sep 21 2020.
