Taking the blame off cormorants

We love to assign blame or shame, no matter the situation. For some crazy reason, this translates to our view of nature. There are a number of species that people don’t seem to like at all, based on nothing other than our desire to assign blame. The double-crested cormorant (Nannopterum auritum) is a classic example of a species of bird that people don’t like and have piled a heap of blame upon.

These birds have been vilified and persecuted by people for hundreds of years. For example, Elizabeth I, the Queen of England in the late 1500s, declared this bird to be a pest and put out a bounty on cormorants. She said they were pests and needed to be eliminated.

To add to this, many books, movies, and poems depict the cormorant as a bad bird, often associating it with the devil. With this kind of bad press, it’s easy to see why this bird is hated even by those who know nothing about it. So, let’s learn a few things about the cormorant.

There are approximately 40 different species of cormorants in the world. The most common in North America is the double-crested cormorant, so let’s learn about this one. The double-crested cormorant is a large, all-black waterbird with large, webbed feet and an impressively large, hooked bill. They weigh only about 2-5 pounds. They have a yellow patch of skin under their lower bill, called gular skin. They have sparkling blue eyes and a blue lining in their mouth, which isn’t very common in birds.

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The common name “double-crested” refers to special feathers on either side of their head that can stand up and away from the head, giving the appearance of two crests. They don’t display these crests very often, so most people never see them, which also contributes to the misunderstanding of this bird.

They have relatively short wings but are still very strong flyers. Their bill is long and thin with a strong down-curving tip, called the nail. They use their bill to catch fish underwater. They use their large, webbed feet to propel themselves through the water, leaving their wings folded at their sides. So, they don’t “fly” through the water – they are true swimmers.

After spending time underwater, the cormorant often sits out in the sun to dry. Cormorant feathers, more specifically, the contour feathers that cover the bird’s body, are different from those of other birds.

At the base, the feather structure is tight and repels water, but the outer part of the feather is open and absorbs water rather than shedding it like other birds’ feathers. So, part of the feather gets waterlogged. This helps the bird stay underwater with less effort, allowing it to be more agile and increasing maneuverability. After all, they need to overtake fish underwater to catch something to eat.

In the past, it was assumed that cormorants didn’t have the oil-producing gland near the base of their tail, called the preening gland. The oil excreted from the gland was believed to give birds their waterproofness. Now we know that it is the feather structure that makes a bird waterproof. Recent studies show that cormorants do have the preening gland, and it’s fully functional. So, once again, we were wrong after making assumptions based on observed bird behaviors.

More recent studies show that birds who sun themselves might be doing more than just drying feathers. There is some evidence that the birds are using the sun to raise their body temperatures and thus increase their digestion rate. Others suggest that the increased UV light from the sun helps them break down and digest their food. Whatever the reason, I am hoping we have learned that making quick assumptions or playing the quick blame game is often proved to be wrong. Until next time …

Editor’s note: Stan Tekiela’s NatureSmart column appears twice a month in the Eden Prairie Local News. Tekiela is an author, naturalist, and wildlife photographer who travels extensively across the United States to study and capture wildlife images.

You can follow his work on Instagram and Facebook. He can be contacted via his website at www.naturesmart.com.