Perfectly legal to carry a shotgun for bear defense or whatever. Just make sure its legal where you go (specifically if you go to any parks, no guns in national parks and Im pretty sure it varies from one provincial park to the next).
Just make sure that if you are stopped by a CO, you can reasonably explain yourself. By this, I mean if you get stopped out in the bush, and you are lugging around a hunting rifle with a big scope on it, you'll have a much better chance of being accused of poaching. Alternatively, if you have a small pump shotgun, and a bunch of slugs then your excuse of predator defense is much more believable.
Also, I wouldn't carry any bird shot on me. Just one less thing to be questioned about. (If you feel you need some in case you get lost and need it for a survival situation, then make sure its buried in your bag and not easily accessible)