A young double crested Cormorant eyes its only natural enemy - a human

The double breasted Cormorant is a bird that’s very good at the basics.

In flight, it’s narrow body, long neck and streamlined head combine with powerful rapid-beating wings (adult wingspan 45-48”), to produce straight line airspeeds superior to other species found near water, including ducks, geese, and gulls – an ability that fits well with the Cormorant’s pattern of seasonal migrations.

In the water, Cormorants can dive to depths of 60 feet. They capture their prey in a long beak, the upper part of which is hooked, carry it to the surface and toss the captive in the air, swallowing it head first. Reportedly, prey up to 12” in length are within their capability.

The cormorant does not have a significant natural enemy, and is indigenous to virtually the entire world, including the United States and much of Canada. However, in the second half of the 20^th century, the North American species’ encountered a man-made enemy so potent that by 1973, only 125 mating pairs remained on the largest national rookery, Galloo Island at the eastern end of Lake Ontario, prompting the bird’s addition to the migratory bird protection act.

The enemy was DDT. In the 50’s and 60‘s before it was banned, the pesticide was responsible for the destabilization of many species, but few have recovered as emphatically as the cormorant.

If you care to listen to Lake Ontario charter fishing captains, cormorants were to blame for what in the late 1990’s was seen as a sharp drop off in smallmouth bass populations, especially in the Henderson Harbor area near Galloo, where some 8,000 nesting pairs had taken up residence.

More recently, reports of cormorant population explosions have come from virtually everywhere in the United States. But until now, nowhere has the hue and cry been so loud as from Henderson Harbor, home to a few dozen charter operators. In 1998, apparently frustrated by what they saw as government foot-dragging, an unknown individual or individuals landed on Galloo and slaughtered 1000 birds, including nestlings.

A California animal rights group offered a $1,000 reward for the capture of those responsible for what it called "a brutal act of animal cruelty." Federal wildlife officials labeled the incident, "a brazen act of environmental terrorism," and initiated a full field investigation that netted…zip. Instead of co-operation, investigators encountered a group of locals, virtually all of who had motive, opportunity, and the weaponry to have committed the slaughter. In the face of such a united front, the investigation went nowhere and no one was ever arrested.

Fast forward ten years. Cormorants have now spread to every available roost on the lower Great Lakes. They line the breakwall at Oswego like silent homeland security sentinels. In tributaries, they perch on every deadfall and exposed rock, and the problems they present in Lake Erie extend beyond their predatory habits. Cormorants don’t just multiply rapidly, their droppings are highly acidic and where they nest in large numbers, droppings change the PH of the soil. Trees die, and native plants disappear. Other birds abandon their nests, and the islands cormorants take over become barren. 

In an interview quoted in a May 11, 2008 issue of the Toledo Blade, Mark Sheildcastle, of Ohio’s Crane Creek Wildlife Research Station, said the problem is largely a product of excessive human development. “It’s a symptom,” he said. “We really shouldn’t be looking at the cormorant as the problem. The problem is the lack of habitat...”

On Lake Erie, the backbone of management plans of both Canadian and US agencies now routinely include selective culls conducted by sharpshooters. This is in stark contrast to government reaction on Lake Ontario back in 1998; ("A brutal act of animal cruelty.") ("A brazen act of environmental terrorism.") The murder of thousands of birds is no longer cruel, it’s “a management plan.” I suppose those responsible for the Galloo massacre will now qualify for patriotic medals.

According to the official new spin, left unchecked, cormorants have the potential to significantly alter the ecosystem they dominate, but this view is challenged by Wildlife advocates such as Liz White, director of Animal Alliance of Canada, (as quoted in the Toledo Blade). White insists that if not for human intervention in the first place (DDT, etc) the islands now being managed would have evolved differently. She claimed that controls are being applied to appease people, not because there’s any scientific justification.

Other naturalist agencies such as the Aububon Society are taking a softer "it's complicated" line. The sad fact remains that when animals and humans come into conflict, animals always lose, and cormorants, one of nature’s marvels of evolution, seem to be next in line. It’s impossible not to admire them for the things they do well. Might it be conceivable that they’ve become so dominant not in spite of us, but because of us?

Consider the man-made creation we call the St. Lawrence Seaway and the round goby, one of thousands of ballast water immigrants polluting the Great Lakes; the goby feeds on Zebra mussels (another invader) and has now established itself in huge populations. Fortunately, the goby is not an agile creature. We’ve heard reports of perch populations rebounding – in direct contradiction to dire predictions that the goby would outcompete smaller species like perch and cause populations to decline even further, it appears that perch (not particularly agile themselves) are finding the goby to be an excellent new source of food - right along with the cormorant. As they say, it’s an ill wind that blows no good, and in this case we’re thankful that nature, though stressed by us, can be trusted to always work toward equilibrium. Meanwhile, have you petted a cormorant today? Might as well learn to love them, cause unless we invent some new form of DDT just for birds, they’re probably here to stay.