Its victim was an unsuspecting pigeon in one of the city's most densely populated neighbourhoods.
The gyrfalcon, which escaped from its owner last September, was spotted on an apartment balcony clutching the freshly caught pigeon in its talons.
Feathers flew as the falcon moved about the porch with its kill before it swooped away above the Plateau-Mont-Royal district. The predatory bird belongs to the world's largest falcon species.
Its owner, who identified the bird from photos, said he's been trying to find the falcon since it bolted during a training exercise in the western Quebec town of Hudson last fall.
The female, bracelet-wearing bird was only about four months old when it flew the coop and Carl Millier hadn't even given it a name.
Millier was saddened by the loss and is pleased to see his falcon appeared to be alive and well.
"Whenever you spend time with a bird and you lose it, for sure (you're sad)," Millier said in an interview.
"I tried for about a week to find the bird in my area."
But catching the falcon is far from a lock for Millier, who figures he has only a slim chance of actually getting it back.
The falcon, he said, was photographed last Wednesday around 250 kilometres from Montreal in Quebec City. The identification number on the bracelet was visible in one high-resolution photo.
Millier, who had begun training the gyrfalcon for the sport of falconry, also runs a business that uses predatory birds to patrol airports. The goal is to keep other birds from flying into airplane engines.
In falconry, trained gyrfalcons are used by expert handlers to hunt game birds, often in eye-popping fashion as they dive-bomb their prey from great heights.
"Due to its size, its hunts are quite spectacular," said Millier, noting his wayward, three-pound bird is particularly imposing for a gyrfalcon.
A McGill University wildlife expert said gyrfalcons have been coveted for centuries for their falconry abilities, characteristics that made them popular with kings and emperors.
"The gyrfalcons are the largest and most powerful of all the falcons," David Bird said.
"That's the Lamborghini of raptors."
While a few pairs of peregrine falcons are known to nest in Montreal, Bird said gyrfalcon sightings are very rare in the city because they usually live in Arctic regions.
Bird said gyrfalcons are expert hunters known to feed on bigger prey such as ducks, seabirds and even large Arctic hares. He also said a gyrfalcon has been filmed taking down a Canada goose, which has wings powerful enough to break an adult human's arm.
But Bird said the gyrfalcon, which is also an official symbol in the Northwest Territories and Iceland, does not pose a risk to humans or their small pets.
A pigeon, on the other hand, would make for a mouth-watering target, Millier said.
"It's an easy prey and they're numerous," he said.
Millier said his best chance of retrieving the bird, which was born and raised in captivity, would likely come by using a fishing-like technique with a live pigeon as the bait.
He said the strategy, used by scientists, involves tying the pigeon into a leather harness covered with about 40 nooses of fishing line. Millier would hold a strap attached to the harness and hide, hoping for the falcon to snatch the pigeon and entangle its feet in the fishing-line loops.
But the toughest part, he added, will be tracking down his cagey target.
"If the bird has survived a long time like this and it has approached people, then for sure I've got a chance," he said before offering a non-scientific estimate on the outcome.
"I'd say I've maybe got a 20 per cent chance."