The article says they probably swam across the Johnstone Straight, from the mainland. There's no mention whatsoever of introducing grizzlies to any nearby islan

The article says they probably swam across the Johnstone Straight, from the mainland. There's no mention whatsoever of introducing grizzlies to any nearby island. If you're asking hypothetically, I'd guess it comes down to whether the islands were separate ecosystems, but Wikipedia would be a much better source than me.