Canada’s Goose
In spite of the fact that some regions of Canada have lost as much as 70 per cent of their original wetlands in the past 100 years, the Canada Goose continues to thrive in North America.
It’s hard to believe, now, that the species was once in serious decline. Formerly victims of the deadly duo of guns and poisons, Canada Goose populations have recovered over the past three generations and have returned to most of their former range.
Now comes another threat — overcrowding and disease.
In some areas a lack of predators and an abundance of winter food has put an end to annual migration for many individuals. Here in Calgary, for example, a typical winter will see over-wintering flocks that number from the high hundreds to the low thousands.
Only a severe, prolonged freeze can succeed in temporarily driving over-wintering Canada Geese from Calgary. Then as a soon as the weather breaks and open water reappears, the geese return.
But when such a large number of birds try to share such a small amount of open water, the threat of disease wiping out hundreds of birds in a few days becomes acute.
In areas where the water is still or nearly still, Mother Nature is unable to flush away excrement. As winter’s long nights wear on, the water beneath the over-wintering flock becomes a steadily more disgusting toilet.
All day long the birds churn up the dirty water as they tip up and use their bills to search the mud beneath the filthy water looking for something to eat. In conditions like these, a single sick bird can quickly cause the death of nearly every bird in the flock.
Humans contribute to these frequent winter tragedies in two significant ways. By feeding over-wintering waterfowl, they encourage them to not to migrate. And by leaving food scraps and garbage out for coyotes, they encourage the goose’s natural predators to leave the geese alone.
Meanwhile, on a grander scale, a warming climate leads to milder winters and more open water in Calgary’s many parks and natural areas. So the need to migrate south lessens with each passing year.
One has to wonder how many more generations of Calgarians will pass before the flying vee of migrating geese becomes lost in the annals of our natural history.
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Brent Johner has been writing about urban wildlife since 1998. Many of the articles here first appeared in the Calgary Herald, Calgary Gardening magazine or on Talk About Wildlife. Brent has also done dozens of radio, television, newspaper and magazine interviews on the subject of urban wildlife.