The AOU Check-list (1957) lists Destruction Island in northern Washington as the most southerly known breeding site of the Rhinoceros Auklet (Cerorhinca monocerata). Since then and particularly since the late 1960s, several new breeding sites of this species have been discovered in British Columbia, Oregon and California. The status of C. monocerata in the southern part of its range is either changing or at least becoming better known. In this paper we wish to 1) report some additional breeding sites in the southern part of this species’ range, 2) summarize all the new records of the past ten years, and 3) comment on the significance of these records. We also compare Rhinoceros Auklet activity patterns during the breeding season in the new southern extreme of their range with their activity patterns farther north.