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Art by Barry Kent MacKay
Still another vignette painting, two in fact, done for an upcoming book on cormorants (the publisher estimates it will be out just over a year from now). The first shows an adult Great Blue Heron in a plumage that artists seldom show -- a post-breeding adult, as it would appear in early August. In breeding plumage they have slender black plumes that extend from the back of the head...an extension of the black area that goes back from the region of the eye, as well as elongated, slender plumes at the base of the neck, and more brightly coloured unfeathered portions -- beak, lores (area in front of eye) and even the feet.
With it is an adult Double-crested Cormorant, who has shed the twin crests that give the species its name, but are maintained only during the spring. Both birds are alert, nervous about something they see...and that could be the viewer! That causes them to keep their plumage tight and compressed, both ready to take off, the cormorant with wings already spread. The joy of illustrating a book about one species is that I get to do this...to show a variety of aspects of that species.
I also wanted to show the two species together and when I saw a scene like this at a large mixed-cormorant-heron colony on Middle Island, Lake Erie, in August, well, the scene became the inspiration for this study. The "wildlife managers" constantly claim that because cormorant excrement kills off the trees the cormorants nest in, they are damaging the survival of the herons. Also, cormorants may help themselves to the sticks used by herons for their own nests (both species make similar nests, often close to each other in the tops of trees in their shared colony).
But this has been going on for countless thousands of years, and in fact it seems that the two species have a "relationship". At Presqu'ile Provincial Park, here in southern Ontario, Great Blue Herons were never recorded as a nesting species until after the cormorants established a colony, and then the herons moved in.
I have a theory, that the herons, when they nest in the tops of trees,
need open areas, both so they can see approaching danger, and so they can
land and take off without getting tangled in branches. They are a gangly
bird. And so I think that in general they may wait until trees are past
their prime and starting to die back and lose their smaller upper twigs and
branches before they start nesting in tree tops, in tall, deciduous trees,
although I have also seen them in quite dense foliage in dry brush or
mangroves in tropical and subtropical colonies. Often they will choose trees
that have been flooded, and thus their health compromised and the upper
foliage thinned out. It is not only, I think because the wetland thus
created provides food, but the trees are then better suited for their
nesting needs. Of course these colonies are not permanent and once the trees
die and fall, the herons move on. Conversely, trees that grow where there is
a high water table, or species adapted to grow with their roots wet, seem to
better survive cormorant (and heron) excrement, the theory being that the
water dilutes the concentrations of nitrates creating nourishing fertilizers
at concentrations dilute enough to benefit, not hurt, the trees.
The two species do not seem to compete much for food; herons fish in shallows and along shorelines, eating small fish, but also the frogs, snakes, salamanders, crawfish and so on that cormorants tend to avoid. Cormorants are almost exclusively fish-eaters and can access deeper water.
Why People Kill Cormorants...
Copyright © Barry Kent MacKay
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