Forest Preserve District of Cook County, Illinois
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Cormorants
Nature Bulletin No. 560-A   March 29, 1975
Forest Preserve District of Cook County
George W. Dunne, President
Roland F. Eisenbeis, Supt. of Conservation

CORMORANTS
Infrequently, during their spring and fall migrations, Cormorants, also called Shags, may be seen diving for fish along Chicago's lake front or on forest preserve waters such as McGinnis Slough near Orland Park. Large numbers pass through the state but a few remain and nest, summer after summer, in colonies such as the one at Lake DePue in the Illinois River valley.

Many of the cormorant's physical characteristics and habits mark it as a primitive bird, one little different from an ancestral type that lived in a remote geological period. It is related to two other grotesque fish-eaters which occasionally wander into Illinois, the pelican and the water turkey (or anhinga). At first sight, the cormorant looks like a bird that might have come to life from a museum exhibit illustrating the Age of Reptiles.

The Double-crested Cormorant -- so-called because of a tuft of curly feathers on each side of the head -- is the only common species in this central part of the continent. It is a large black water bird about the size of a small wild goose. Flocks of them are sometimes seen sitting upright, with wings outspread, in dead trees, on pilings, or on rock ledges along shore. In flight they form lines or V's like geese except that they occasionally sail. The wings are also used to add speed under water where the rather long stiff tail feathers serve as a rudder. The short powerful legs and feet, with all four toes webbed, are well-suited for rapid swimming in pursuit of fish. The slender beak is hooked at the tip for grabbing and holding large fish.

Most double-crested cormorants winter along our southern coasts and nest in certain localities from the Gulf of Mexico to northern Canada. The nests, of sticks, weeds and grass, are usually built in colonies in tree tops -- often among the nests of a heron rookery. Others nest on rocky islands. The 2 to 4 bluish-white eggs, about the size of large hen's eggs, have a chalky coating. After 29 days of incubation, they hatch. At first, the blind naked young look like little wiggling greasy rubber bags. In a few days they grow a covering of black down. To eat, they poke their heads far down into the parent's throat pouch and rummage for predigested fish soup.

Two other species of cormorants rarely stray as far inland as Illinois. One, the somewhat larger European Cormorant, is world-wide in distribution and is common along our North Atlantic coast. Another, the Mexican, is much smaller. Throughout the world, about thirty species are known. They feed almost entirely on fish and, except one, are much alike except for size. The rare Harris's Cormorant of the Galapagos Islands cannot fly.

Since ancient times in China, cormorants have been tamed and trained to catch and bring back fish to their owners, just as falcons were used to catch game in midair or on land. Sometimes they were completely domesticated, their eggs hatched under hens, and the young fed by hand on chopped eel and other fish. Training started when they were fully grown and feathered. One would be tied by a string to a stake at the water's edge. At a whistle signal it was pushed into the water and tossed a bit of fish. Then, after a different whistle, it was pulled back and rewarded again. As soon as the bird got the idea, live fish were used. Then it was graduated to a boat or raft and a string tied around its neck so that it couldn't swallow the fish it caught. With several of these trained birds, a Chinese fisherman was in business. The Japanese use them for sport fishing and, in Elizabethan England, the Master of the Cormorants was a member of the royal household.


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