Cormorant: A fish-eating
by Barry Kent
One of the strangest
things about the double-crested cormorant is its apparent
ability to generate irrational hatred in humans.
is one of 39 living (and one recently extinct) species belonging
to a family of aquatic birds known by the tongue-torturing
name, Phalacrocoracidae, more popularly called cormorants
or shags. They are found on every continent and are related
to pelicans and gannets.
People think they
know a great deal about the super-abundant double-crested
cormorant, the only species to nest in Ontario. But much
of what they know is myth. Along with many other species
of fish-eating wildlife, cormorants are a scapegoat fishermen
love to blame for any real or imagined depletion of fish
stocks. I have challenged everyone who hates cormorants
to name one naturally occurring fish stock, anywhere in
the world that has been wiped out by any cormorant species,
anywhere, any time. None have.
do eat fish, to the tune of about one pound per day per
adult bird, and obviously are a factor in fish population
numbers. But study after study has demonstrated double-crested
cormorants do not seriously affect fish stocks. They mostly
eat species of fish of no commercial value and not favoured
by sporting anglers. They also do not take fish that feed
"desirable" game and commercial fish species except
in highly contrived circumstances (for example, on a fish
farm, or in a small bay or behind a dam). Cormorants certainly
can cause temporary shortages of fish at the local level,
but any more than that, and the cormorants, themselves,
would die. They don't have alternative food sources.
They eat so few
commercial fish compared to their population it usually
makes little or no statistical difference to the numbers
of fish available to anglers. As one study put it, "
study reviewed convincingly demonstrated double-crested
cormorants' negative impact (on) sport or commercial fisheries."
There are collapses in once robust fisheries reported from
around the world, whether cormorants of any kind are present
or not, but it is a large suite of factors that have caused
those fishery collapses, and primary among them is overfishing
Still, a lot of
fishermen hate the highly visible cormorants. Unlike factors
that have truly profound impacts on population sizes of
any given species of fish-from zebra mussels to changes
in water temperature to introduced non-native salmon species
with voracious appetites for native fish.
And, here in Ontario,
they are seen as a new creature in our midst. Fishermen
remembering (accurately or otherwise) lots of big fish from
a childhood in which cormorants were rare or absent, now
worry that there are fewer fish. Cormorants are now common
and increasingly apparent. This begs the question-steeped
in the most basic laws of physics-of how a species, dependent
on a finite food supply, can exponentially increase, while
its food decreases; the belief is that the double-crested
cormorant is a recent invader and our native fish have not
evolved defences against the marauder.
But like so much
that is believed about this bird, it simply is not true.
Ironically, the double-crested cormorant is playing a positive
role in terms of protecting native fish stocks, feeding
on invasive fish species whose presence is deleterious to
One of the most
frustrated scientists I've ever chatted with is Linda R.
Wires, of the University of Minnesota. She has studied cormorants
for years, authored many peer-reviewed papers, and cannot
understand how both the general public and wildlife managers
manage to ignore the facts science produces. She spoke to
me as she and a colleague were preparing a paper on the
history of the double-crested cormorant in the Great Lakes
It is an endemic
North American bird (with a small population in the West
Indies) that has, within all recorded history, ranged from
the extreme northwest of the continent to the east coast.
It is inconceivable to think that it has, until recently,
somehow avoided the largest fresh water system in the world-the
Great Lakes and the complex and vast pattern of post glacial-lakes
and rivers covering most of the province of Ontario.
Linda Wires points
out that, in 1886, the newly formed American Ornithologists
Union began the compilation of bird species of North America
in a frequently renewed annotated checklist, popularly known
as the "AOU Checklist." It is considered the definitive
reference on bird distribution in North America, and is
still published periodically as new information becomes
available. That first edition, in 1886, gave the Great Lakes
as part of the range of the double-crested cormorants. Then,
as now, the AOU included the top ornithologists in the continent,
and they clearly recognized the species as inhabiting the
So, too, did Philo
Louis Hatch, M.D., (1823-1904) in his pioneering state bird
book, Birds of Minnesota, published in 1892, and the Hamilton-based,
noted pioneer Ontario ornithologist, Thomas McIlwraith (1824-1903)
in our very first provincial bird book, Birds of Ontario
In my personal library,
I found that The Natural History of the Toronto Region,
Ontario, Canada, edited by J. H. Faull, Associated Professor
of Botany, University of Toronto, 1913, and the noted Toronto-based
ornithologist, J.H. Fleming, listed the double-crested cormorant
as occurring in Toronto as rare migrant. I checked other
old books I own. In Birds of America, whose Editor-in-Chief
was T. Gilbert Pearson, 1917, (and still in print), we read
under the species account of the double-crested cormorant,
"Distribution-Eastern North America; breeds from Central
Saskatchewan, southern Keewatin, northeastern Quebec and
" and also in the U.S.
There are numerous
other such early descriptions of the double-crested cormorant's
range, all including the Great Lakes, where they either
nested, or visited during migration to and from the northern
Here in Ontario,
not too far from the North Channel-where locals consider
the species invasive and the Ontario Ministry of Natural
Resources is oiling eggs-the Ojibwa people, as reported
in 1893, named a rock that is part of a cliff face, "Kakakeshiwishtagwaning",
which translates to "cormorant's head." They must
have been familiar with cormorants.
My old friend, the
late James L. Baillie, (1904-1970) spent most of his career
in the department of ornithology of the Royal Ontario Museum,
where he was an assiduous chronicler of distribution patterns
of birds in Ontario, working in the field most summers through
the middle decades of the 20th century with other museum
staff, to document bird distribution in Ontario at that
time. Even then, in a paper published in 1947, when the
decline in this native species was at its height, he recorded
it as having been found at Carney Rocks, Black Bay, on the
northwestern shore of Lake Superior, reviewing material
from "about 1920."
Jim Baillie also
noted a report by fishermen (who, then as now, persecuted
the species relentlessly) that cormorants nested in the
general region of the Mink Islands, in Lake Huron, in 1919.
While no actual verification, in the form of preserved specimens
or photographs, was obtained (hardly a surprise), Baillie,
who was extremely conservative about such matters, was inclined
to believe the report was accurate.
cormorant was also noted by American ornithologists to be
breeding in Agawa Bay of Lake Superior's eastern shore in
1926, where the residents noted that "the cormorants
had nested there for years." This suggests they were
there prior to the 1920s, although by then, egging and persecution
by fishermen had done most of the damage to our Great Lakes
population-damage that the application of DDT would virtually
complete. (However, there is apparently no time in recorded
history when double-crested cormorants were totally absent
from the Great Lakes).
Cormorants are generally
considered inedible, so one does not expect to find cormorant
bones in archeological digs of kitchen middens-bone piles
from meat consumed by early people-but in fact they were
found at a site Brent County, on the Niagara Peninsula,
that dates back to the 16th century.
The myth that the
cormorant is alien to our waters seems to stem from the
lack of preserved specimens of nests or newly hatched young.
In the old days of ornithology, all sightings of bird species
were considered, at best, "hypothetical" if they
were not backed up by preserved specimens (later clearly
identifiable photographs became acceptable). And by this
criterion, although the double-crested cormorant was reliably
recorded at the Lake of the Woods in the 1790s, it did not
become "official" until 1924, when nests were
formally collected and recorded on an island in Lake Nipigon.
It is probable there
are more cormorants in Ontario now, than ever before. No
one can say for sure that there are, but if we go far back
in time, we find that the conditions were probably less
favourable for the kinds of fish cormorants eat, in the
centuries following the retreat of the very ice age that
left this province with its immense legacy of lakes, including
the Great Lakes system. But they were here, and as colonial
nesters, it is likely that there were large populations
wherever suitable populations of fish existed.
Nature, even when
left alone, is not static. Add human activity, and there
is a rapid dynamic that sees many changes in relatively
short time spans. This is particularly true of such mobile
species of wildlife as birds and fish. One would be hard
put to find a species of bird that exists in Ontario now,
in essentially the same numbers and in the same locations,
as it did one, two, three or nine hundred years ago.
The landscape has
changed, and so has the mix of flora and fauna that share
our space. Humans have either accidentally or intentionally
been responsible for the introduction of hundreds of species
of plants and animals that would otherwise be absent from
Ontario. And species like the northern cardinal, once unknown
in Ontario, have moved north in response to warmer winters
and the increased availability of food, thanks to humans.
But the double-crested
cormorant has been here all along. Like the wolf, hawk,
owl and other predators, the cormorant is often seen as
a competitor for game, maligned and hated. But like those
species, it is part of our natural environment, a native
member of our wildlife heritage.
This is an original story,
first published in The Country Connection Magazine,
Issue 47, Summer/Autumn 2004. Copyright Barry Kent MacKay.
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