Bryan Brillhart Photography Presents “Dig Imperial Beach” Bird of the Week, the “Double-Crested Cormorant”
Feb 09, 2016 12:59PM
● By Paul Spear
Bryan Brillhart of Bryan Brillhart Photography presents us with the “Bird of the Week”. This week’s bird is the “Double-Crested Cormorant(Phalacrocorax auritus)”. The column will provide a picture of a bird(s) locally photographed and we will have background on the bird.
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“Dig Imperial Beach ” Bird of the Week, the “Double-Crested Cormorant ”
This week’s “Bird of the Week” is the Double-Crested Cormorant (Phalacrocorax auritus), a sea bird in the cormorant family. This dark, long-bodied diving bird floats low in the water with its thin neck and bill raised. The double-crested cormorant is a large waterbird with a stocky body, long neck, medium-sized tail, webbed feet, and a medium-sized hooked bill. It has a body length of between 70–90 cm (28–35 in) long, with a wingspan of between 114–123 cm (45–48 in). Double-crested cormorants weigh between 1.2–2.5 kg (2.6–5.5 lb). This species has dark-colored plumage with bare super-loral and gular skin that is yellow or orange. An adult in breeding plumage will be mostly black and 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, which has a more restricted distribution in North America, mainly on the Canadian maritime provinces. It can, however, be distinguished 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 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.
It perches upright near water with its wings half-spread to dry. The Double-crested, which rarely looks noticeably crested in the field, is the most generally distributed cormorant in North America, and the only one likely to be seen inland in most areas.
Its population has had its ups and downs, with a long-term decline because of persecution at nesting colonies until about the 1920s, then a gradual increase until the 1950s. Numbers dropped again through the 1960s, probably owing to the effects of persistent pesticides. After DDT was banned in 1972, populations began increasing again, and are still increasing and expanding their range through the present day. In some regions, wildlife management agencies have culled some nesting populations because of concerns that these birds would crowd out other colonial water birds.
Double-crested cormorants inhabit coasts, bays, lakes, and rivers. They are very adaptable, and may be found in almost any aquatic habitat, from rocky northern coasts, to mangrove swamps, to large reservoirs, to small inland ponds. Nests are in trees near or over water, on sea cliffs, or on ground on islands.
They forage mostly by diving from the water surface and swimming underwater, propelled by feet, but may sometimes use their wings as well. They may forage singly or in groups in clear or muddy water at the mid to upper levels of water more often than near the bottom.
Their diet consists of fish and other aquatic life. Diet varies with the season and place, including very wide variety of fish, crabs, shrimp, crayfish, frogs, salamanders, eels, snakes, mollusks, and plant material.
Double-crested cormorants usually first breed at the age of 3 years. Nests are in colonies, sometimes mixed with wading birds and others. Males display to females on the water by splashing with their wings, swimming in zigzags, and diving, bringing up pieces of weeds. At nest sites, males display by crouching and vibrating their wings while calling. Nest sites are near the water on cliff ledges, on ground on an island, or at any height in trees. Nests, built mostly by females with materials brought by males, are a platform of sticks and debris, lined with finer materials.
After mating, females lay 3-4, sometimes 1-7 bluish white eggs becoming nest-stained. Incubation is by both sexes at about 25-33 days, but typically 28-30. Both parents feed the nestlings. After 3-4 weeks, young may leave ground nests and wander through the colony, but return to their nests to be fed. Usually first flight is at about 5-6 weeks, and nestlings are probably independent at about 9-10 weeks.
There are quite a few double-crested cormorants in the estuary and along the beach near the river mouth now. Their distinctive behavior of spreading their wings while perched is an easy way to recognize them. Look for this bird while enjoying a walk there. Until next week, good birding!