Double-crested Cormorant

The double-crested cormorant, Nannopterum auritum, is a robust waterbird with a long neck and a stout, hooked bill. Its plumage is predominantly black, with some individuals displaying a greyish back and coverts. During the breeding season, adults develop distinctive nuptial crests above their eyes, which can be white, black, or a combination thereof. The species is named for these crests, and it also features a patch of orange-yellow facial skin. The double-crested cormorant measures 70–90 cm in length, with a wingspan of 114–123 cm, and weighs between 1.2 and 2.5 kg.

Identification Tips

Adults in breeding plumage are mostly black with possible white crests and orange facial skin. Non-breeding adults lack the crests and have more yellowish facial skin. Juveniles are grey or brown with lighter underparts. The double-crested cormorant can be distinguished from the great cormorant by its more extensive yellow throat and bill, and from the neotropic cormorant by its range and size.

Habitat

This species is found in a variety of aquatic environments, including rivers, lakes, and coastal areas. It is adaptable and can be seen perching with wings outstretched to dry its feathers after diving.

Distribution

The double-crested cormorant is widely distributed across North America, from the Aleutian Islands in Alaska to Florida and Mexico. It is a migratory bird, with some populations moving southward in winter to ice-free coastal areas.

Behaviour

The double-crested cormorant is an adept swimmer and diver, using its feet for propulsion to catch prey. It is often observed standing with wings spread to dry its non-waterproof feathers. In flight, it has a characteristic posture with its bill tilted slightly upward.

Song & Calls

The vocalizations of this species include a deep, guttural grunt, particularly noticeable during the breeding season and when in colonies.

Breeding

Breeding occurs in a variety of coastal and inland water habitats. The double-crested cormorant nests in trees, on cliffs, or on the ground in colonies, often with other waterbirds. It constructs stick nests and exhibits a gregarious nature.

Similar Species

The great cormorant and neotropic cormorant are similar in appearance but can be differentiated by range, size, and the extent of yellow on the throat and bill.

Diet and Feeding

The double-crested cormorant primarily feeds on fish, diving underwater to capture its prey. It may also consume amphibians, crustaceans, and insects. It is known to regurgitate pellets containing indigestible parts of its meals.

Conservation status

Once threatened by DDT, the double-crested cormorant has experienced a significant population increase in recent years. It is currently listed as Least Concern by the IUCN. However, it has faced persecution in areas where it competes with human fishing interests.