Canada's, Ontario's efforts bearing fruit
Jul. 15, 2006. 01:00 AM
Darryl Stewart
Special to the Star
As a result of the amazing recovery in the breeding population of the bald eagle and peregrine falcon in Ontario, the McGuinty government has announced that the bald eagle will now be considered endangered in only part of the province, while the falcon's status has been improved from endangered to threatened.
These two raptor species have bounced back from the edge of extinction following two decades of hard work and the recovery efforts of government wildlife officials.
During the 1960s and early 1970s bald eagles, ospreys and peregrine falcons, especially those in Ontario's Great Lakes region, were having alarming reproductive problems. It was noticed that the eggs of many of these birds were being produced with shells so thin they were unable to withstand the wear and tear of incubation, and so their populations were falling dramatically.
This reproductive failure was found to be a result of the effects of chlorinated hydrocarbon pesticides in the environment, most notably DDT and DDE being ingested by adult birds through the food chain.
The pesticides had found their way into the water system and had been absorbed by the bald eagles and ospreys by way of their fish prey; peregrine falcons feed essentially on birds, especially pigeons, and the poisons were absorbed directly through their own food supply.
Key species at the top of the food chain, such as birds of prey, are sensitive indicators of the general health of the environment, and are especially vulnerable to changes in their ecosystems. That's why all three raptors were included on the list of the Endangered Species Act (1973), and the use of the offending pesticides were banned in some quarters and heavily restricted in others.
Only a few years after the pesticide restrictions in Canada, these birds began to reproduce more successfully and to re-establish themselves in some of their former Great Lakes breeding areas. The osprey now appears to have recovered to the point where it was not included on the Ontario Birds at Risk list (2003), while the bald eagle and peregrine falcon are still considered to be at some risk. The list is regulated under the provisions of the Endangered Species Act (ESA), which legally protects species.
The osprey is more skilled in catching fish than the bald eagle is, and for its pains, it's often hijacked and harried into relinquishing its prey, whereupon the eagle swoops and snatches the fish before it enters the water. This trait of piracy caused Benjamin Franklin to oppose the choice of the bald eagle as the avian emblem of the United States; Franklin favoured the wild turkey, a bird he considered to be of a far nobler character.
With the new provisions of the Ontario government announced June 29, the bald eagle will remain as an endangered species only in areas south of the French and Mattawa Rivers. North of there the eagle's status will change to special concern.
Although bald eagle breeding populations have overcome pesticide-related reproductive failures in many parts of the province (it is estimated that there are about 1,400 pairs in Ontario), they remain vulnerable to factors such as illegal shooting, accidental trapping, poisoning and electrocution.
As for the peregrine falcon, it is the eastern subspecies F.p. anatum that is of concern. Peregrines have increased markedly in Ontario due in no small part to the province's recovery and release program started in 1977 in Algonquin Provincial Park. An estimated 70 pairs are believed to dwell in the province
However, the future of the peregrine is far from secure. Those birds that migrate to parts of Central and South America, where pesticide restrictions are not so stringent, are still at risk. In addition, they are threatened by their capture for falconry, shooting and poaching.
Darryl Stewart is a Toronto-based naturalist.
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