Double-Crested Cormorants are Twice the Fun

Rick Lewis    Adult double-crested cormorants have black plumage with dark grey wings and juveniles have lighter grey-brown plumage.

Sacred or Satanic?! The cormorant, which often may be seen drying its extended wings, is sometimes associated with nobility and sacrifice because of the resemblance of the pose to the the Christian cross. In contrast, Milton’s epic poem “Paradise Lost” describes the devil as assuming the form of the cormorant. In Nordic countries, the cormorant is commonly seen as a good omen, representing the spirits of loved ones lost at sea. 

The double-crested cormorant is the slim black bird we often see swimming in the waters or resting on the shoreline around Alameda. The bird is about three feet long with a wingspan of more than four feet. The face is bright yellow with a turquoise eye. 

The interior of the bird’s mouth is bright blue. In breeding season, the bird has a crest on the head; however, the crest is generally black on birds as far south as Alameda, so the crest is hard to spot on the black bird. In the water, a cormorant will often show only its head and long snake-like neck while the body is nearly submerged. Double-crested cormorants are known to have lived to the age of at least 22 years. 

All cormorants dive from the water surface in search of fish or other small prey. Some species of cormorants are known to dive as deep as 150 feet! They may fly as far as 40 miles in search of the best fishing. They propel themselves underwater with their webbed feet.

Many waterbirds “waterproof” themselves by preening their feathers with secreted oil. A cormorant’s flight feathers are not as waterproof as a duck’s. Cormorants secrete much less preening oil, allowing their feathers to absorb more water when diving. 

This could make diving easier by releasing trapped air under the feathers. To dry out after diving, they will often perch on rocks or jetties and assume a pose half-stretching their wings in the sun with the neck extended. Their beaks have a hook at the tip to help hang onto a slippery fish dinner. 

Double-crested cormorants have long nested in the Bay Area. The nests are typically bulky piles of sticks. The male usually brings most of the building materials while the female arranges the sticks to her satisfaction. 

The female commonly lays three or four light blue eggs. The eggs require about four weeks to hatch; the nestlings are not ready to leave their nests for another four weeks. Both parents feed the chicks. At about 10 weeks, the chicks are ready to fend for themselves. The young birds reach breeding age in three years. 

At the time of the Gold Rush, thousands of miners and others arrived at the tiny settlement now called San Francisco. They immediately wanted something to eat. An important item on the menu was seabird eggs from the Farallon Islands. Enterprising people went out to the islands to gather as many seabird eggs, including cormorant eggs, as possible, destroying nests and driving off the birds in the process. The breeding colony was nearly destroyed! The seabirds at the Farallones began to recover by early in the 20th century. By then, however, a new threat arose. 

The pesticide DDT was widely and carelessly used to kill pests. Although seabirds were not the intended target, their food was contaminated by the spreading DDT. The pesticide caused the birds to lay eggs with such thin shells that the shells broke before the chicks were ready to hatch. After DDT was banned, the cormorants began to recover. 

Today, a favorite nesting place for the double-crested cormorant is in the structure of the Bay Bridge, close to the water for food, and far from mammalian predators. The new eastern section of the Bay Bridge has cormorant nesting platforms to replace the nesting areas destroyed when the old section was demolished. 

Cormorants have been domesticated for more than 1,000 years. King James I of England is said to have loved to watch cormorants trained to catch fish; he employed a “Master of Cormorants.” For this purpose, the cormorants are raised in captivity to be tame. The owner will tie a string around the bird’s neck so that the bird can swallow small fish, but not bigger fish. 

The fisherman will pull the bird back to the boat by the string and take the stuck fish from the bird’s throat. While this activity is no longer performed commercially, it is performed as a tourist attraction in parts of Asia. 

There are two other species of cormorants found in this area: Brandt’s cormorants and pelagic cormorants. While those species are seldom seen from Alameda, they can be seen nesting on Alcatraz Island.