Chemical Bans Helps Revive Eagle Population In Toronto, Experts Say

For the first time in Toronto's history, a pair of bald eagles have nested.

Their presence highlights the spectacular recovery of a bird that was nearly extinct, as well as the improved health of Toronto's enormous green spaces and rivers.

Banning Of Chemicals

Bald eagles, more connected with North American images than any other species, are a rare example of ecological success.

Experts believe it is a significant moment because bald eagles were only removed from Ontario's list of at-risk species last year.

According to Michael Drescher, an environmental planning and conservation expert at the University of Waterloo, the number of bald eagles in North America plummeted in the 1960s, with only a few hundred nesting pairs remaining.

He also said that the return of bald eagle nesting pairs throughout the continent, which is currently estimated to be in the tens of thousands, is partly due to the restriction of certain pollutants, particularly dichlorodiphenyltrichloroethane (DDT), a once widely used insecticide that was prohibited in the 1970s.

According to Jon Spero, lead keeper of birds and terrestrial invertebrates at the Toronto Zoo, exposure to DDT causes bald eagles to deposit brittle eggs that can fracture under the weight of the incubating bird.

The number of bald eagles in southern Ontario remains fewer than in previous periods, but their recovery is a positive sign of the quality of the water and fish on which they rely.

"It's a sign that an ecosystem is healthy when we see bald eagles returning to it," said Spero.

Drescher adds that bald eagles now have a larger food source, as small mammals and fish that eagles depend on have profited from pollution reductions.

The finding comes just over a decade after another pair of bald eagles made their home at the Royal Botanical Gardens' Cootes Paradise near Hamilton.

Two years later, the first eaglets hatched on the Canadian shoreline of Lake Ontario in almost 50 years.

Ecosystem Healing

The remarkable success of the bald eagle recovery echoes the billion-dollar endeavor to rehabilitate the green spaces and marshes that run through Toronto.

But the eagles aren't the only species telling conservationists that the land and water are healing.

Two years ago, an angler captured a 42-inch, 20-pound muskie in the city's harbor, the first time the predatory fish had been seen in more than three decades. Northern River Otters were once driven out of the area. Now, a couple has been sighted wandering from park to park with their five offspring.

However, the appearance of eagles in the city represents a deeper level of ecological recovery, implying that the bustling center of Canada's greatest metropolis is more than just a good habitat for hardened urban species such as squirrels, coyotes, and raccoons.

Instead, if everything goes well, it can house a pair of birds who, despite their intimidating appearance, are quite sensitive to disturbance.

"I'll admit that I'm worried. Eagles are really charismatic species and people have this intense desire to connect with nature. That curiosity can sometimes dissolve the willpower to stay away," said Karen McDonald, who works at the Toronto and Region Conservation Authority's restoration and infrastructure division.