Birdwatchers are flocking to Boundary Bay in Metro Vancouver to catch a glimpse of snowy owls, which migrate south only once every four or five years.

"They are fantastic. They are wonderful,” said Anne Murray, a nature writer from Delta, B.C. “Two feet tall, 60 centimeters, the biggest of the North American owls."

The Arctic circle is home to the snowy owl year round, most years, when they feed on the native lemmings.

But every four years or so, the lemming population sees a decline, making food hard to come by.

So the owls leave their arctic home and travel south to places like Boundary Bay or northern California looking for other prey.

But as the CBC’s Renee Filippone reports, some naturalists are concerned that eager photographers are scaring the birds off.