Confined to northeast Asia, this distinctive Guillemot is molting out of winter plumage. Although listed as "least concern" by IUCN, the Japanese population appears to be deteriorating with 19 out of 28 breeding colonies now gone according to a 2015 study by Senzaki et al. Based on plumage, it has been suggested that this species may be more closely related to the Snow's subspecies of Pigeon Guillemot (C. c. snowi) than Snow's is to typical Pigeon Guillemot (C. columba). Both have an all dark body in breeding plumage lacking the obvious white wing patch of typical Pigeon Guillemot. Incidentally, the illustration of the adult winter Snow's Guillemot in Brazil (2019) is incorrect, portraying a typical Pigeon Guillemot instead. Winter Snows look like winter Spectacled, but lack the white eyering (A. Jaramillo pers. comm.). Compare images in the OBC gallery. Canon PowerShot SX60.
References:
BirdLife International 2018. Cepphus carbo. The IUCN Red List of Threatened Species 2018: e.T22694867A132578646. http://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T22694867A132578646.en. Downloaded on 21 May 2019.
Brazil, M. (2018) Birds of Japan. Helm. London.
Masayuki Senzaki, Makoto Hasebe, Yoshihiro Kataoka, Yoshihiro Fukuda, Bungo Nishizawa, and Yutaka Watanuki "Status of the Spectacled Guillemot (Cepphus carbo) in Japan," Waterbirds 38(2), 184-190, (1 June 2015). https://doi.org/10.1675/063.038.0207
Nettleship, D.N., Boesman, P. & Garcia, E.F.J. (2019). Spectacled Guillemot (Cepphus carbo). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/54065 on 21 May 2019).