A wildlife biologist in Thunder Bay says the boreal owl population here has remained steady this winter even though naturalists in Minnesota say they have found many of the birds dead or ill.

Brian Ratcliff noted the owls have been leaving their normal range in search for food and have encountered heavy snow, making it hard to hunt for small rodents.

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Thunder Bay orinthologist Brian Ratcliff. (Supplied)

"We're seeing these birds locally here and I suspect that they're having a hard time some place farther north, and thus they're moving out of the north and moving farther south," he said.

People are reporting seeing owls around their backyard feeders, he added.

"Especially the great grey owl, which is the largest of the owl that we're seeing down here, but the smaller boreal owl has been showing up in their backyards, usually associated with bird feeders," Ratcliff said. "They're coming in [and] probably feeding on small mice that are at the feeders at night."

Younger owls affected

Ratcliff, admits it’s hard to tell general health without being able to capture and examine the birds.

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Boreal owls are heading south in search of food, out of their natural habitat, observers say. (borealbirds.org)

He said the northern boreal owls are going through what is called cyclical irruption, a natural, cyclical phenomenon that happens when hungry owls that normally winter in northern Canada head south in search of food.

According to a recent article in the Asssociated Press, other irruptions have been reported recently in New England, as well as southern Ontario and Quebec, and parts of British Columbia.

Irruptions tend to involve young owls because older owls are more experienced hunters and know their territories better and so are better at finding food.

Younger northern owls also don't know about dangers from humans — like cars — so they're more likely to end up as road kill. They're often weak by the time they make it south, and some species might not recognize the local small mammals as food.

Starving owls are drawn to homes, where they try to prey on mice that gather spilled seed from bird feeders or that hole up in garages and woodpiles.

With files from Associated Press