Written by Gerry Smith
posted on April 13, 2017 12:40
If you are convinced the Double-crested Cormorant is a demon bird, sent from the dark side to gobble up all OUR fish, then maybe you should stop reading now. My perspective is much more nuanced regarding this North American native species. Hopefully readers will find information that counters the general view prevailing in much of our region. This species does not deserve the scorn heaped upon it by many in the angling community. Too many myths surrounding the perceived impacts of this bird, on the fisheries of our region are taken as gospel.
A nest of the Double-crested Cormorant
Photo courtesy Bill Munro
The Double-crested Cormorant is a medium sized black colonial waterbird of ancient evolutionary lineage. Closely related to pelicans, many species of cormorants occur worldwide. In northeastern North America, two species occur. The Great Cormorant is present all around the North Atlantic and maintains a population along our northeastern Atlantic coast. The Double-crested Cormorant also occurs on the Atlantic coast and throughout the Great Lakes, to the interior of North America. Plumage in cormorants ranges from the basic black of adults to variable browns in immatures. The double crests of our bird are breeding season feathers, atop the head that can be manipulated as part of courtship.
Cormorants are usually seen in flying flocks, passing low over the water, or diving for small prey fish. When nesting on islands, or human structures, their large nests are obvious by sight and smell. Just as human cities, without sewage control, may be unpleasant to our nose, the nesting colonies of cormorants, gulls, terns, and herons are odoriferous. Thus, there-in lies the rub,why humans are not favorably impressed by these stinky large black birds that eat OUR fish.
This perception is then reinforced by the Urban Myths, about this species that are prevalent in the media and on the street and thus the boogie bird is born.
In nature, as often in human affairs, truth is far more nuanced than a thirty second sound bite about these evil cormorants. The myths about this species and its impacts on area fisheries abound. These Include:
- They are an invasive species. Not true, this is a native North American bird with populations in several parts of the continent. It's status in the Great Lakes, prior to the mid- twentieth century, is open to debate. In my opinion, small numbers of cormorants probably occurred in the Eastern Great Lakes-St Lawrence region, prior to European settlement. The Settlers from Scotland and Ireland had a history of antipathy, toward other cormorant species in Europe. Active persecution in the nineteenth century probably eliminated the small local populations. This species was later greatly impacted by DDT and other chlorinated hydrocarbon pesticides, throughout the Great Lakes region. The banning of DDT and similar chemicals, in the early 1970s, allowed recovery in Double-crested Cormorant populations. Combined with improving water clarity, as a result of pollution control laws, these factors allowed rapidly growing populations to reoccupy the region, in substantial numbers, over a relatively short time period.
- They selectively pursue gamefish, such as bass. Modern predator prey theory, reinforced by many field studies, clearly shows that predators select the most readily available prey, within their prey group. In the case of a fish-eating species, they take the most available fish of the appropriate size. Currently, for Double-crested Cormorant, that appears to be large numbers of the exploding population of the invasive round goby and similar species. Basically, when almost any dive will allow a Cormorant to have a goby lunch, why would a bird expend energy to selectively chase a bass?
- A Cormorant eats several pounds of fish a day. Total nonsense, since any such bird would be unable to fly. A few gobies a day provide adequate calories to keep any Cormorant in fine fettle, during the breeding period, when they are present in our region.
- Cormorants destroy vegetation on their nesting sites. This is true of all colonial waterbirds and is simply part of a natural humans people caused. Well, when all colonial birds nest on a site, the nitrogen from their excreta occurs at a level that "burns" the roots and does destroy vegetation. Under natural conditions, along the St. Lawrence, occupied Islands would be abandoned, nutrient enrichment would subside to a level where it actually favored developing vegetation, woody growth would occur, and herons and cormorants return. This cycle has been disrupted by human occupation of many formally suitable nesting sites, so now the birds have ever fewer options to move.
- I think the greatest myth of all is "they are taking OUR fish". Excuse me, but I have yet to see a Cormorant carrying a fish labeled "property of". From my point of view, all fish swimming along are subject to capture, by the most competent fishing animal that is best at what it does. Hmm, I suspect therein lies the rub, with those among anglers that don't like competition.
I want to make it clear that I am NOT opposed to well-designed Double-crested Cormorant Management, based on current science. Control of this species, to protect some fisheries and nesting habitat for other smaller colonial waterbirds, is often justified. Efforts on Oneida Lake, in Central New York, appear to be justified. Management efforts in our region, however, are often based on out of date research that is nearly a quarter century old. Given the major changes in aquatic ecosystems, invasive species nutrient loading etc., there is a clear need for new studies and management planning.
I suspect this is part of the reason that a lawsuit, launched by a group of former federal scientists, was successful in 2016. These folks challenged the US Fish and Wildlife Service control permit, under which NYSDEC efforts are conducted. The result was NO management last year and this year may be impacted as well. The reverberations from this legal challenge are already being felt locally, with near hysterical calls from some fishing guides, for drastic action to protect THEIR fish.
This is not a good situation; some persons in the past have violated wildlife laws in Canada and the United States and attacked cormorants illegally. Such actions are intolerable under any circumstances. Any cormorant control must be based on sound science and adaptive management and conducted only as absolutely essential. These intensive management efforts are costly in dollars and time of agency personnel, as well as being difficult to sustain long-term. Regular success evaluations are needed, and control should cease if the situation dictates. In my opinion, the hysteria surrounding this bird, amongst some anglers, is unfairly reflected in much of the local media, resulting in a skewed perception of this species throughout our region. Scapegoating the Double-crested Cormorant locally, is no different than claiming Wolves are killing all the caribou in Alaska. This view puts pressure on managers to do something, often some wrong, and often leads to bad management of OUR natural resources.
By Gerry Smith
Gerald A. "Gerry" Smith, is an ornithologist who can often be found leading fellow bird enthusiasts, on guided Thousand Islands Trust (TILT) tours, throughout the year. He is a graduate of the biology program at SUNY Oswego, is one of the founding members of Derby Hill Bird Observatory, along Lake Ontario. He was the first staff ornithologist at Derby Hill, for the Onondaga Audubon Society. Gerry was President of the Onondaga Audubon Society and in 2010, he published the popular guide book, "Birding the Great Lakes Seaway Trail.”