Scientific Name: Phalacrocorax auritus
Description: This dark, long-bodied diving bird floats low in the water with its thin neck and bill raised; perches upright near water with 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.
Habitat: Coasts, bays, lakes, rivers. Very adaptable, may be found in almost any aquatic habitat, from rocky northern coasts to mangrove swamps to large reservoirs to small inland ponds. Nests in trees near or over water, on sea cliffs, or on ground on islands.
Feeding Behavior: Forages mostly by diving from surface and swimming underwater, propelled by feet (may sometimes use wings as well). May forage singly or in groups. May forage in clear or muddy water, at mid to upper levels of water more often than near bottom.
Diet: Fish and other aquatic life. Diet varies with season and place, includes very wide variety of fish, also crabs, shrimp, crayfish, frogs, salamanders, eels; sometimes snakes, mollusks, plant material.
Eggs: 3-4, sometimes 1-7. Bluish white, becoming nest-stained. Incubation is by both sexes, 25-33 days, typically 28-30. Young: both parents feed the nestlings. After 3-4 weeks, young may leave ground nests and wander through colony, but return to nest to be fed. Usually first fly at about 5-6 weeks, probably independent at 9-10 weeks.
Nesting: Usually first breeds at age of 3 years. Nests in colonies, sometimes mixed with wading birds and others. Male displays to female on water by splashing with wings, swimming in zigzags, diving and bringing up pieces of weeds. At nest site, male displays by crouching and vibrating wings while calling. Nest: Site is near water on cliff ledge, on ground on island, or at any height in tree. Nest (built mostly by female, with materials brought by male) platform of sticks and debris, lined with finer materials.
Young: Both parents feed the nestlings. After 3-4 weeks, young may leave ground nests and wander through colony, but return to nest to be fed. Usually first fly at about 5-6 weeks, probably independent at 9-10 weeks.
Conservation Status: Population has had ups and downs. Probably long-term decline (because of persecution at nesting colonies) until about 1920s, then gradual increase until 1950s. Numbers dropped again through 1960s, probably owing to effects of persistent pesticides. After DDT was banned in 1972, populations began increasing again, still increasing and expanding range through the present day. In some regions, wildlife management agencies have culled some nesting populations because of concerns that they birds would crowd out other colonial waterbirds.
Notes: Images captured at Town Lake in Austin.