The Double-crested cormorant (Nannopterum auritum) is a water bird widely distributed across North America. It is a relative of the frigate bird and is skilled in diving for small fish. Its feathers, like those of all cormorants, are not waterproof and it must spend time drying them out after spending time in the water.
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DiurnalDiurnal animals are active during the daytime, with a period of sleeping or other inactivity at night. The timing of activity by an animal depends ...
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CarnivoreA carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of a...
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PiscivoresA piscivore is a carnivorous animal that eats primarily fish. Piscivorous is equivalent to the Greek-derived word ichthyophagous. Fish were the die...
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AltricialAltricial animals are those species whose newly hatched or born young are relatively immobile. They lack hair or down, are not able to obtain food ...
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NatatorialNatatorial animals are those adapted for swimming. Some fish use their pectoral fins as the primary means of locomotion, sometimes termed labriform...
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
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CongregatoryCongregatory animals tend to gather in large numbers in specific areas as breeding colonies, for feeding, or for resting.
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OviparousOviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
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AquaticAn aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract ...
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MonogamyMonogamy is a form of relationship in which both the male and the female has only one partner. This pair may cohabitate in an area or territory for...
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FlockingFlocking birds are those that tend to gather to forage or travel collectively. Avian flocks are typically associated with migration. Flocking also ...
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ColonialColonial animals live in large aggregations composed of two or more conspecific individuals in close association with or connected to, one another....
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MigratingAnimal migration is the relatively long-distance movement of individual animals, usually on a seasonal basis. It is the most common form of migrati...
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starts withThe Double-crested cormorant is large with a stocky body, long neck, medium-sized tail, webbed feet, and a medium-sized hooked bill. It has dark-colored plumage with bare supra-loreal skin and gular skin that is yellow or orange. An adult in breeding plumage will be mostly black with the back and coverts being a dark grayish towards the center. Nuptial crests, for which the species is named, are either white, black or a mix of the two. These are located just above the eyes with the bare skin on the face of a breeding adult being orange. A non-breeding adult will lack the crests and have more yellowish skin around the face. The bill of the adult is dark-colored. The Double-crested cormorant is very similar in appearance to the larger Great cormorant but it can be separated by having more yellow on the throat and the bill. The plumage of juvenile Double-crested cormorants is more dark gray or brownish. The underparts of a juvenile are lighter than the back with a pale throat and breast that darkens towards the belly. As a bird ages, its plumage will grow darker. The bill of a juvenile will be mostly orange or yellowish
Double-crested cormorants occur widely across North America, breeding locally along all coasts as well as extensively in Florida, in the center of the continent, and along the St. Lawrence Seaway, the Great Lakes, and in Mexico, the Bahamas, Belize, and Cuba. Cormorants usually winter along the coast of the Pacific Ocean from Alaska to Mexico, and along the Atlantic and the Gulf coasts from Belize to North Carolina, as well as inland in ice-free areas along lakes and large rivers. They inhabit a range of marine and aquatic inland habitats. They need water for feeding and perches nearby, such as rocks, sandbars, trees, pilings, shipwrecks, wires, or docks where they can rest and dry out during the day.
Double-crested cormorants are diurnal birds. They are very gregarious and can be found in large and small groups at the breeding grounds, and in winter, often feeding in large flocks. They breed in colonies and migrate in large groups. This species feeds during the day, diving for fish for 30-70 seconds, as deep as 1.5-7.5 m (4 ft 11 in-24 ft 7 in). After diving, the birds stand with their wings outstretched for a long time for them to dry, as they are not waterproofed fully. Double-crested cormorants swim low down in the water, often just their head and neck showing, and dive from the water’s surface. Their feet are used to propel them along. They fly low over the water, their bill tilted upward slightly, sometimes flying out from the colony in a long, single-file line. They use physical displays and calls to communicate with each other, using their limited range of calls for certain social situations, but usually being silent.
Double-crested cormorants are carnivores (piscivores). They primarily eat fish, but also insects, crustaceans, and amphibians.
Double-crested cormorants are monogamous. This means that males mate with only one female and females mate with only one male. The colonies they breed in can number as many as three thousand pairs. Males choose a nest site, then advertise for a female, standing to perform a “wing-waving display” to show off the brightly-colored skin on the head and neck. A male will also engage in elaborate courtship dances, including a dance in the water where he presents a female with nest material. These birds defend a small space immediately around their nest which is smaller than one meter across. Breeding takes place from April to August, peaking from May through July. A pair works together to repair an old nest or to build a new one on the ground or sometimes in a tree. The female lays 4-7 pale bluish white chalky eggs and both parents incubate them for 25 to 28 days. Chicks are altricial when hatched, and both parents care for them. They begin to leave their nest at 3 to 4 weeks of age. They can fly starting about 6 weeks of age and are able to dive when they are 6 to 7 weeks old. Chicks are completely independent at 10 weeks of age and breed once they are 2 years old.
These birds are susceptible to pesticide poisoning and other contaminants, as well as to oil spills. Sometimes they are killed or injured when caught by fishhooks, trawls, gill nets, and lobster traps. Also, they are very susceptible to disturbance while nesting. Adults leave their nest unguarded when disturbed, leaving chicks and eggs open to being eaten by gulls and further predators, and in danger of overheating in the sun.
According to the All About Birds resource, the continental population is more than 630,000 breeding birds. Overall, currently, Double-crested cormorants are classified as Least Concern (LC) on the IUCN Red List and their numbers today are increasing.
Social animals are those animals that interact highly with other animals, usually of their own species (conspecifics), to the point of having a rec...