Northern bobwhite: A staggering 25 million fewer today than in the mid-1960s, according to the New York-based National Audubon Society. (National Audubon Society/Canadian Press)
It's not been a good year for the birds and the bees. A few months ago, media outlets were seized with the unexpected collapse of otherwise thriving bee colonies across the U.S. and in parts of Canada, a mystery that still has scientists baffled.
Now, the National Audubon Society in the U.S. has reported on a devastating decline in the common bird. The 20 most popular species — the warblers and songbirds that frequent our backyard feeders, as well as the small ducks and game birds that scurry through fields and wetlands — have seen their numbers drop an astounding 54 per cent over the past 40 years, the NAS says. The top 10 birds in this category have seen their numbers dwindle by an average of more than 70 per cent.
That translates to 432 million fewer sparrows, chickadees, eastern meadowlarks, hummingbirds and northern bobwhites, among others, today than in 1967, when a similar census was taken. Do you think Mother Nature is trying to tell us something?
The good news, if any can be drawn from the Audubon Society's work, is that few of these once-common birds, perhaps only two or three species, are in danger of totally dying off. (Biologists, mind you, are keeping a close watch on the grasshopper sparrow, the loggerhead shrike and perhaps even the ironically named common tern, which is not doing well outside of a few dozen protected areas.)
But the sad fact is that this decline has been taking place slowly and inexorably, virtually right under our collective noses. At least 18 of the 20 species the NAS focused on are common to Canada. These are the birds of the backyards, the jazz songs, the kids' books.
One year, the evening grosbeaks are so plentiful they are cleaning out the feeders. Then they just don't seem to show up again, part of a 78-per-cent decline over 40 years.
Counting birds
Are these numbers right? "It's hard to know exactly," says bird biologist Bob Montgomerie of Queen's University in Kingston, adding that the counting methods the Audubon Society uses is based on volunteer birders and can be fraught with errors.
For the study, researchers looked at bird populations of more than half a million, which is the definition of a "common bird." They then compared databases for 550 species from two different bird surveys, the Audubon's own Christmas bird count and the U.S. Geological Survey's breeding bird survey that is taken every June, both relying on reports from so-called citizen-scientists.
Individual numbers may be off here and there. But generally speaking, this is a decline that was first identified in Britain in the mid-1980s and seems to be continuing apace.
Basically, Montgomerie says, the species most affected are those that did well "in old-time agriculture" with its hedgerows, sloughs of water and abundant insect life. They are suffering today under the newer techniques of single-crop commercial farms with their heavy pesticide use and little in the way of ground cover.
Arctic birds may be doing better, he suggests. His students, who are on their summer field trips, are reporting continuing large numbers wherever they go. But bird ecology is a fragile state of being.
As the Nature Canada Society observes, global warming and urban sprawl are forcing many species northward in search of food and into greater competition with other species. They're also facing different predators.
That's the dilemma for the greater scaup, observes the NAS's chief researcher, Greg Butcher. Its traditional breeding ground on the open tundra has been transformed into a more forested region and this has provided greater cover for nest predators.
In the northern Hudson Bay area, thick-billed murres, one of Canada's hardiest birds, are having to adjust to an aggressive mosquito population that is peaking earlier in the summer before the young birds are strong enough to survive the onslaught. Many are dying, literally, from having the blood sucked from their tiny feet.
Habitat change
According to the Audubon Society, the reasons for the decline are many. Urban sprawl (backyard patios instead of gardens), global warming and industrialized agriculture are the leading causes.
But mining, lumbering and spraying for spruce budworm and other pests in Canada's wide-ranging boreal forests — one of the most important way-stations for hundreds of species of songbirds and others — is also an important factor. So is the loss of grasslands in the Prairies as well as the invasion of the Great Lakes by such foreign species as zebra mussels, which reduce the insect population that many birds feed on.
Climate change appears to be pushing birds and other species further northward, often into competition. The Ontario Breeding Bird Atlas suggests that at least four species of usually southern birds, such as the red-bellied woodpecker and the tufted titmouse, have been moving into the province.
Some are doing well. Some are driving out other species in the competition for food.
Bird populations often go up and down in great number, depending on natural catastrophes or sudden warming trends, which can affect breeding and plankton growth upon which fish and sea birds in turn depend.
The National Audubon Society study, however, suggests that the overall trend is downward.
