Smaller numbers occur in subtidal waters.
Prefers undisturbed islands with friable soil for digging burrow, as well as productive, pelagic waters near breeding colony for feeding. Activity patterns uncertain. North of Oregon, appears more nocturnal, and probably forages at night. From October to April, occurs in large numbers on California's pelagic waters. The semiprecocial young remains in burrow 35-45 days, and leaves for sea before reaching adult size.