Doubled-crested Cormorant, Nannopterum auritum
Doubled-crested Cormorant, Nannopterum auritum. Birds photographed in the greater Puerto Adolfo Lopes area of Baja California Sur, March 2019.
Doubled-crested Cormorant, Nannopterum auritum. Birds photographed in the Florida Everglades, February 2022.
Doubled-crested Cormorant, Nannopterum auritum. Bird photographed in the Los Cabos area of Baja California Sur, February 2023.
Double-crested Cormorant, Nannopterum auritum. Bird photographed in the Los Cabos area of Baja California Sur, December 2019. Photograph courtesy of Dr. Tom Bartol, Carlsbad, California.
Double-crested Cormorant, Nannopterum auritum. Photograph taken in coastal waters off Fort Lauderdale, Fort Lauderdale, Florida, October 2021. Photograph and identification courtesy of Faith Hubsch, Fort Lauderdale, Florida.
Background and Identification
The Double-crested Cormorant, Nannopterum auritum, is a member of the Phalacrocoracidae Family of Cormorants and Shags. Although this species is a waterbird, they are rarely observed out of the sight of land. It gets its name from the small tufts, or “crests,” that appear on the heads of adults during the breeding season, although these are not always prominent. When perched, the Double-Crested Cormorant often stretches its wings out to dry, as its feathers are not fully waterproof. In Mexico, they are called Cormorán Orejudo.
This species is a large and dark-colored cormorant. They range in length from 70 cm (2 feet 8 inches) to 90 cm (2 feet 11 inches) and have average body mass (males and females) of 1.2 kg (2 lbs 10 oz) to 1.5 kg (3 lbs 5 oz). Double-crested Cormorants are sexually monomorphic, meaning the sexes appear similar. They have a mostly black appearance, with a slight greenish sheen on the feathers, and a bright orange-yellow throat pouch. Its long, hooked bill is well-suited for catching fish. Juveniles are brownish and lighter on the chest.
Habitat and Geographical Range
The Double-crested Cormorant is a waterbird found in almost any aquatic habitat along the coast. They are common in bays, lakes, reservoirs, and rivers. These birds are commonly found along both the Atlantic and Pacific coasts, as well as inland near large freshwater bodies. Breeding colonies are typically found on islands, cliffs, or remote shorelines, where they build nests in trees, on the ground, or manmade structures such as bridges or docks.
Their range extends from southern Canada through the United States and into Mexico, with some populations migrating seasonally between breeding and wintering grounds. In Mexico, the Double-crested Cormorant is found along the entire coast of the Gulf of Mexico and in all waters of the Pacific south to Puerto Vallarta. During the winter, they move to more temperate regions, often congregating along coasts and large inland lakes.
Common Misidentifications
The Double-Crested Cormorant can be confused with other species of cormorants, particularly the Neotropic Cormorant, Nannopterum brasilianum (smaller and has a more slender neck and bill, along with a more restricted range, mainly in the southern United States and Central and South America). Additionally, some may confuse the Double-Crested Cormorant with the Anhinga, Anhinga anhinga (dark plumage with a much longer neck and a straight, pointed bill rather than the cormorant’s hooked one).
Conservation Status
From a conservation perspective the Double-crested Cormorant is currently considered to be of Least Concern with stable, widely-distributed populations. This species has faced challenges in the past due to human activity. In the mid-20th century, the use of pesticides like DDT severely impacted cormorant populations, but conservation efforts and the banning of such chemicals have led to a significant rebound. Despite their recovery, cormorants remain controversial in some areas due to conflicts with fisheries. In some regions, their numbers have grown to levels where they are seen as competitors for fish stocks, leading to management and control measures in certain areas.