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HAMILTON -- For the first time in decades, bald eagles have successfully hatched on the north shore of Lake Ontario -- news that has bird enthusiasts flocking to the Hamilton area to spot the eaglets.

The parents have been nesting in the marsh at Cootes Paradise Nature Sanctuary in recent years, but the successful hatching of healthy young marks a historic first for the region, suggesting the majestic birds are once again beginning to thrive.

Species-at-risk biologist Kathryn Harrison, of the Royal Botanical Gardens which administers Cootes Paradise, said it’s believed to be the first time since 1955 that eaglets have hatched anywhere along Lake Ontario’s shoreline between Kingston and Hamilton.

"There have been a few (breeding pairs) in the St. Lawrence and in the Gananoque region and there are some offshore, but on the shore of Lake Ontario on the northern side, this is the first successful nest," Harrison said.

"And in general on Lake Ontario, there are less than a dozen that have been successful in recent history. So it's pretty significant for us in terms of saying 'we've got the habitat, we've got the water and so the eagles have chosen to come back here.'"

First glimpse

RBG staff first built a nest for the eagles when the pair were first spotted in the area in 2009, hoping to entice them to take up residence.

The eagles promptly built their own nest, where they remained until 2010. In 2011-12 they abandoned that nest and instead settled into the one staff built located more than 70 metres off the ground in a pine tree overlooking the marsh.

Then in mid-February of this year, staff noticed the adults had begun taking turns sitting on the nest, sparking speculation that the female had laid eggs. Sure enough, at the end of the 35-day incubation period a hatchling made an appearance, poking its head up out of the nest and taking a look around. A day later its sibling did the same thing.

Harrison said staff were ecstatic and word quickly spread through the birding community. In the week-and-a-half since the eaglets hatched, there has been a steady stream of visitors, she said.

"It was snowing on Monday and you'd still see a constant stream of people coming out, curious, some on their second or third visit to see the eagles and see the hatchlings, so it's been great," Harrison said.

"They're pretty majestic birds and it's easy to just sit there and spend an afternoon watching."

On Wednesday, despite sub-zero conditions and bitter winds, families, hardcore birders and even tourists made the hike to the marsh boardwalk to view the birds.

A troubled history

Bald eagles were once a common sight on the shores of Lake Ontario. In the 1800s it's estimated there was one nest for every kilometre or so of shoreline.

But European settlement devastated the birds, as they were considered a dangerous predator and hunted as a result. The population started to rebound in the mid-1900s, but the species was rendered all but extinct by the 1980s due to pesticides such as DDT.

"What happened is the eggs started thinning and when the eagle was on the nest the eggs would break or you'd see deformities in the newly hatched eaglets," Harrison said.

"The worst period was in the 1980s where there was actually no successful reproduction on the Great Lakes or in southern Ontario at all, so it was a pretty dark time."

But bird groups, conservation authorities and the RBG have worked hard in recent years to help the population rebound. Cootes Marsh, the largest wetland on the western shore of Lake Ontario, has been a major focus of those efforts.

The installation of a fishway to prevent invasive species from entering the marsh, the planting of cattails and other native species to control pollution, and upstream sewage overflow controls have all helped establish an environment where eagles can find and hunt the fish they need to survive.

The hatchlings serve as evidence that the efforts are working.

"It's a sign of the progress the eagles are making in re-establishing themselves and it's also a sign we're doing a good job in restoring our habitat and the progress RBG has been making in habitat restoration in Cootes Paradise," she said.

Leaving the nest

The eaglets are currently growing at a rate of about 116 grams per day and are expected to reach full size in about two months. At one metre from beak to tail and with a two-metre wingspan, it will be a crowded nest.

Harrison said the eaglets will likely leave the nest when they are about 70-days-old. They will then stay around the nest learning to hunt and forage for food for some time, before venturing out on their own.

Young eagles typically remain nomadic for the first couple of years after leaving the nest, travelling extensively in search of food until they reach sexual maturity at age four or five, when they begin looking for a mate.

While the parents are expected to continue to call Cootes Paradise home in years to come, Harrison said the young are likely to find their own area to settle and may never return to their birthplace.