Floating by sometimes beats flying high.Photo courtesy of John Hess

Double-crested cormorants (Phalacrocorax auritus) will soon be making their way south along the lakefront, flying in haphazard V-formation or in loose flocks or long lines that can number between a few hundred to a few thousand birds. The original extent or number of cormorants on the continent before European colonization is unknown.  Today they are widely distributed on inland lakes and along rivers and coasts from the Aleutian Islands and Nova Scotia south to Mexico.

Cormorants are large (28-35 inches long) dark water birds with a hooked beak and obvious orange/yellow skin exposed around the eyes and throat. Both sexes look alike. Not so obvious are the wispy double crests, which grow only during breeding season. The double-crested
cormorant’s diet is primarily fish, along with some amphibians and crustaceans. 

The cormorant is particularly well-adapted to herding fish. Typically, it swims low in the water, with only its slim neck and head visible, and dives from that position.  It has fine eyesight that allows it to spot prey in murky water or even occasionally to dive from great heights to its underwater target. The adult’s nostrils are permanently closed, and it breathes through its mouth above water. It overcomes the tendency of buoyant objects to rise to the surface by having modified feathers and a modified pelvis for powerful, rapid swimming. It pursues fish by vigorously paddling with its feet and steering with its tail. Its modified head muscles and a hooklike nail at the tip of its upper bill help it grasp prey rather than spear it.  It may eat small prey underwater, but to eat larger prey it will surface, toss the fish in the air and swallow it whole, headfirst.

After eating, it will fly to a perch and sit with its wings extended. It appears to be drying its outer feathers, but there is scant understanding of this behavior.  The cormorant’s flight is powerful but labored, and its takeoff from the water is almost comical; it hops and flaps along the water’s surface before finally becoming airborne. 

Cormorants have a complex and elaborate courtship. In one display, the pursuing male splashes energetically with both wings, zigzags, dives, and emerges with vegetation that he will either toss in the air or drop near his desired female.  The pair unites for the season.  They nest either on the ground or on a dead tree or artificial nesting platform. The male brings the sticks and rubbish for the foundation and the finer lining for the interior, and the female builds. Nests may be refurbished and reused and are considered “filthy” by humans. Cormorants typically lay four eggs, and both sexes incubate them for about 30 days. Three or four weeks after hatching, the young may begin to roam the ground in the colony, but if the nest is in a tree, the young may remain there for six or seven weeks until they can fly.

Before Rachel Carson’s “Silent Spring” appeared in 1962, cormorants were affected by egg-thinning pesticides in the post World War II environment. With the banning of DDT in 1972, cormorants began to rebound, to the dismay of fish farmers and sports fisherfolk. According to the Natural History magazine article, “To Kill a Cormorant,”  “The population growth in the Great Lakes – from approximately 90 breeding pairs in 1970 to nearly 115,000 in 2000 – was fueled, ironically enough, by government managers stocking the region’s waters for recreational angling, often using fish raised in the southeastern aquaculture ponds.” Alewives may also have played a part in their resurgence.

Author John Cole wrote about the cormorant in The Country Journal in June 1983:

“The most commonly-held theory about the origin of birds claims that flying reptiles began evolving into birds during the late Jurassic Period, which ended some 136 million years ago. Frayed reptilian scales became feathers, and teeth disappeared from jaws which became hooked beaks.  Instead of jointed tails, the earliest birds wore a few stiff feathers that were split to stabilize flight better.  The finger bones of what had been reptilian front limbs were covered by the skin of the wings, and the feet of those first flyers retained the four webbed toes of its progenitors.  That description of what paleontologists consider a rare fossil is a reasonably accurate sketch of the present-day cormorant.”

The cormorant has been much maligned through the ages, beginning with the Bible.  The birds are declared “detestable” swarming things and declared unclean. According to Bible commentary, they may be detested because they were considered birds of prey that take their prey live, or perhaps because they were considered voracious or greedy.  It all depends upon the translation and the commentator.  John Milton, in “Paradise Lost,” has Satan spotting Eden and, disguising himself,

“Thence up he flew, and on the Tree of Life,

The middle Tree and highest there that grew;

Sat like a cormorant …

devising death

To them who lived. …”

William Wood, an early New England writer, considered them “the worst of fowles.” Today, the U.S. Fish and Wildlife Service is acting to reduce populations to appease sports fishermen and fish farmers, although the negative impact of cormorants has not been proven. 

Cormorants were first tamed to fish by Asians. They tie a ring around the bird’s neck so that it can catch fish but be prevented from swallowing them, having to give up their catch to the fishermen. 

In summer, cormorants may occasionally be found dotting lakefront piers and almost always perching on a dead shoreline tree at Skokie Lagoons west of the junction of Forestway Drive and Tower Road.  One nearby nesting colony is in Barrington, Illinois, in Baker’s Lake.

Libby Hill is the author of "The Chicago River: a Natural and Unnatural History. She has been writing about birds and trees and Evanston's natural history for the Roundtable since 2004.