Rhinoceros AukletCerorhinca monocerata
14 1/2-15 1/2" (37-39 cm). A pigeon-sized seabird. Dark above with lighter gray throat and breast, white underparts. Slender pale yellow bill, white eye. In breeding plumage, short upright "horn" at base of bill, with white drooping "whiskers" at either side; white plume above eye. Immatures dark gray above, light below with duller, smaller bill and dark eye.