In reply to Calum Nicoll:
Never carried for bears, but have for other things and I briefly worked in the firearms trade as a yoof. It should be good reason for a UK FAC as long as you explain yourself clearly to the Police and have no history of violent crime or mental illness. It can be a painfully bureaucratic process though and I'd suggest seeking advice from someone who's done it on the nuances.
.30-06 or .375 is probably your best bet. I gather that .30-06 is widely available in Canada which is likely a consideration. You will have to fly with rifle and ammo seperate in your luggage and if they loose the ammunition for your wierd and wonderful rifle and you can't buy more locally then its just an expensive stick.
If you are going to buy a rifle I'd suggest getting some training or knowledgeable advise first, to avoid buying something unsuitable which is likely to be dangerous. WMS Firearms training are renown for doing this kind of thing and are viewed as the market leaders, and FarringtonDeer services would probably be able to provide the training you need if you get in touch with them.
Finally though, I would question if its really worth the expense? Unless you are going to be doing this regularly you are probably better off doing a course and hiring a rifle, you won't see much change from £2000 by the time your done.