The population increase south of Morro Bay in winter may be migrants from the north, from Baja California, or the Channel Islands. Thus, many members of population may be local or distant migrators. In San Diego Co., breeds January to July, lays eggs as early as February. Southeast Farallon Island egg-laying extends from April through June. A monogamous, colonial nester.
Incubation is by both parents, period unknown.
Adults often killed in fishing nets. The daily movements of comorants on San Francisco Bay. Bent, A. C. 1922. Life histories of North American petrels and pelicans and their allies. Cogswell, H. L. 1977.