Cormorants are gluttonous birds unpopular with almost everyone


Sportfishermen hate them. Aquafarmers see them as a threat to their livelihood. Property owners watch them threaten the beauty and value of their property.

Cormorants have insatiable appetites for fish. A single bird will consume over a pound of fish every day. The same bird might also kill or wound double that amount that they don’t eat.

I enjoy watching most predatory birds, like hawks, herons, eagles and ospreys. They are efficient and basically clean birds. They also tend not to congregate in large groups.

Cormorants are different. Their nests are often close together and many, often dozens can be seen hunting together. They can really wipe out a school of fish in a hurry. They can also cause hundreds of dollars of damage to an aquaculture pond in a day or two.

A problem farmers and homeowners face is that these birds are federally protected. They fall under the migratory bird protection act. This was a treaty between the United States and Canada that was signed a hundred years ago.

It was designed to protect birds that traveled between the two countries. We usually think of ducks and geese when someone mentions this treaty, but many other birds are included. The double-crested cormorant is probably the most controversial.

During the DDT era, cormorants weren’t much of a problem. Their reproduction was kept in check the same way it was for bald eagles. In 1972 this insecticide was outlawed in the US, and it wasn’t long before cormorant populations began to explode.

This came at a time when aquaculture in the southeastern states was in its early stages. Catfish farms present an easy food source for cormorants. Dense populations of fish quickly draw huge numbers of these gluttonous birds.

One of the reasons cormorants deplete fish populations so much is that they kill and eat so many smaller fish. This reduces total fish numbers drastically. Cormorants also kill and injure many larger fish that they don’t eat. Their serrated hooked beaks can inflict mortal wounds even if the fish escapes.

On aquaculture farms, fish are often fed by automatic feeders. When food hits the water, the fish come to the surface. That’s when cormorants are most deadly. Farmers can obtain permits to control these birds, but it’s still an arduous task. Sometimes farmers use dogs to harass the predators. That usually keeps cormorants from nesting close to the food source, but these birds are relentless.

Depleting wild and domestic fish sources is not the only problem cormorants cause. They eat copious quantities of fish; that’s true. They also produce a tremendous amount of waste. Much of that goes through their digestive systems. They vomit significant quantities of indigestible matter, too.

When bird populations, particularly nesting sites are dense, the ammonia from the excrement and vomit can be toxic to soils. Trees and other plants can die because of it. The residue is also unsightly. It smells terrible too. I realize every creature has a place in the ecosystem, but I see few redeeming qualities of the double-crested cormorant.

Cormorant fishing on a small local pond

Ted Manzer teaches agriculture at Northeastern High School.

About tedmanzer

I grew up in Old Town Maine and got a B.S. at the University of Maine in Plant Sciences/ minor in Botany. From there I moved to West Virginia and earned a M.S. in Agronomy at WVU. I also met my wife there. She grew up in rural WV as the daughter of tenant farmers who raised cattle and hogs. Their lifestyle at times was one of subsistence and I learned a lot from them. I've always been a foraging buff, but combining my formal botanical knowledge with their practical 'Foxfire-type' background opened up my eyes a little more. I now teach agriculture to high school students at Northeastern High School in Elizabeth City, NC. My wife teaches with me and we make a great team. I also write a weekly nature/foraging column for the local paper (dailyadvance.com). I also have written several Christian nature/adventure novels that I plan to publish eventually. One is a five book family saga I call the 'Forgotten Virtues' series. In the first book, Never Alone, a young boy comes of age after his father dies in a plane crash, and he has to make it alone. Never Alone is now available in paperback, Kindle and Nook. The second book, Strange Courage, takes Carl from his High School graduation to his recovery from a nasty divorce. The third book, Second Chances, takes Carl from his ex-wife's death and the custody of his son to his heroic death at age 59. The fourth book, Promises Kept, depicts how his grandchildren react and adjust to his death. In the final book, Grandfather's Way, his youngest and most timid granddaughter emerges from the shadow of her overachieving family and accomplishes more in four months than most do in a lifetime. I use many foraging references with a lot of the plants I profile in these articles in those books.
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