A pair of grizzly bears sighted off the north end of Vancouver Island — believed to have 'island hopped' from the mainland — are a "red flag" says a University of Victoria conservation scientist.

A B.C.conservation officer near Port McNeill B.C. spotted the brown duo swimming from island to island about five kilometres offshore.

It's believed the animals swam all the way from the mainland.

Aboriginal people have stories about seeing the hulking bears — that number about 15,000 in B.C. — on Vancouver Island long ago, but grizzlies do not typically set up dens on Vancouver Island, where smaller black bears are prevalent.

University of Victoria associate professor Chris Darimont believes this move to find new territory is a warning.

"We should be paying attention to their arrival on islands. They have evolved the ability to swim for hundreds of thousands of years. That they have not colonized islands before in any huge way tells us that there is something up. They are now putting that swimming ability to use," said Darimont.

Darimont, who is also science director at Raincoast Conservation, says it is a change in usual behaviour and perhaps a move to colonize new climes, at the same time B.C. is seeing declining salmon populations.

B.C.'s ministry of environment has had reports of grizzly bears on Vancouver Island in the past. (Gary Gulash)

"Bear populations tend to rise and fall with the abundance of salmon. We ought to be very careful, especially in light of other things we are doing to grizzly bear habitat," said Darimont.

Logging sites can also displace bears by disturbing their established dens.

The Ministry of the Environment does get reports of grizzlies on Vancouver Island, but had not for some time.

In 2013 a 500-pound male grizzly was shot near Port McNeill after it killed a dog and damaged property.

On Saturday night, Wellington OPP notified residents in Belwood of a confirmed sighting of a mother bear and cub. (David Wilder)

Grizzly bear territory

In B.C. grizzly bears are reported over four-fifths of the province, but never colonized Vancouver Island or Haida Gwaii, according to a B.C. government report from 2002.

"Their range extends across northern British Columbia, southward in the Coast Mountains to about Jervis Inlet and down through the Rocky, Purcell, and Selkirk mountains to the U.S. border," according to Grizzly Bears in B.C.

Although occasionally sighted on islands close to the mainland in northern B.C. — such as Princess Royal, Pooley and King — the incidences are considered seasonal and rare.