They all have black feet, and in breeding plumage grow white filoplumes on the head and/or neck, and usually also two head-crests and white thigh patches like the present species does. They also share the back-thrown head during the "yawning" and the rapid wing-flutter in courtship display. Among the "Compsohalieus" group, the red-faced cormorant is the sister species of "P. pelagicus". Apart from looking almost alike, these two species also "yawn" many times in a row instead of giving the display just once, twist their bodies before taking flight during courtship, and the male and female post-landing calls are identical. The point-and-gargle response to threats is also an apomorphy of these two species. Its traditional scientific name is the literal Latinized Ancient Greek equivalent of the common name: "Phalacrocorax" is an ancient term for cormorants; literally, it means "bald raven", from "falakrós" (φᾶλακρός, "bald") + "kórax" (κόραξ, "raven"). "Pelagicus" is – like the English loanword "pelagic" – derived from "pelágios" (πελᾶγιος, "of the open seas"). "Compsohalieus", meanwhile, means "sleek fisher"; it derives from "kompsós" (κομψός, "elegant" or "sleek") + "(h)alieus" (ἇλιεύς, "fisherman"). Two subspecies are generally recognized. The difference between them is slight and generally agrees with Bergmann's Rule:  The Amchitka cormorant or Kenyon's shag (P. kenyoni) is a supposed species that was presumed to be closely related to the pelagic cormorant. It was described from the bones of three individuals snared in fishing nets in the late 1950s at Constantine Harbor on Amchitka in the Aleutian Islands. The specific name "kenyoni" honors USFWS biologist Karl W. Kenyon, who collected the type specimen USNM 431164 on 22 February 1959. Some bones from prehistoric middens on Amchitka were also attributed to this taxon.