Distinguishing Characteristics

Large, dark cormorant; typical length 70–90 cm, body mass 1.2–2.5 kg; sexes alike. Males slightly larger than females, but regional (subspecific) differences are much greater (see Measurements, below). Adults have black or dark-brown plumage, with a dull greenish or bronze gloss that may be absent from worn feathers. The orange-yellow skin of face and throat (gular region) is distinctive throughout year. The “double crest” is a poor field mark; these feathers are variable and are fully developed for only a short time early in year. This is the only seasonal change. Immatures are duller and variable, usually paler on upper breast and darker on belly, occasionally uniformly pale below.

Occurs with all other North American cormorants in appropriate coastal areas, but is the only cormorant in most of the interior. Great Cormorant, which breeds in e. Canada and Maine and winters along Atlantic Coast of U.S., is similar but somewhat larger. In adult Great Cormorants, yellow facial skin is bounded posteriorly by distinct white feathered patch, and in full Definitive Alternate (breeding) plumage there is a large patch of white feathers on each thigh, and white plumes over much of the head. Immatures of the 2 species are similar, but young Double-cresteds have pale breast and throat with darker belly, while young Greats have the reverse pattern.

In Texas, Mexico, and the Caribbean (and throughout southwestern states, especially during postbreeding dispersal), Double-crested can be confused with Neotropic Cormorant (Phalacrocorax brasilianus), which is reported as an occasional vagrant north to Minnesota. Latter species is smaller and more slender, and has longer tail and throat-pouch that differs in color and shape; gular pouch of Neotropic forms a horizontal V, colored pale yellowish brown and bordered by narrow band of white feathers ending in point behind and below eye. In Double-crested Cormorant, the pouch is larger, rounded, and more brightly colored. Separation of immatures is more difficult; gular pouches are duller at this age, but color of supraloral skin (between eyes and bill) is brighter in Double-crested and darker in Neotropic (Telfair and Morrison 1995). Immature Neotropics are more uniform in color than are bicolored young Double-cresteds (see Appendix 3 for measurements).

Other cormorants found in w. North America, with the exception of the similar Neotropic (see above), are strictly coastal in distribution. Compared to Double-crested Cormorant, Red-faced (P. urile) and Pelagic (P. pelagicus) cormorants are noticeably small and slender, with red facial skin and gular pouch; breeders have white flank-patches, and immatures are uniformly dark. Brandt’s Cormorant (P. penicillatus) is similar in size and shape to Double-crested, but gular pouch is less conspicuous and colored blue or violet, with band of short, buff feathers posterior to it. Immatures are generally darker than young Double-cresteds, with uniform rather than bicolored underparts.