BOTTOM LINE: You gotta pay to play, but this is basically the only place to see northern gannets in…read moreNorth America.
As (one of) the only breeding sites for northern gannets in North America, Bonaventure Island is a destination unto itself that is a must see, even if you're not a birder. But first, you gotta pay a fairly hefty $42 for the privately-owned ferry ride (it's billed as a "tour" and they do take you around the entire island so you can see birds along the escarpment, which you otherwise wouldn't see, but still...), and the standard $9 entrance fee of most provincial parks.
But once you're in, oh my! I'd recommend the Sentier des Colonies hiking trail straight to the far side of the island and then returning along the coastal Sentier Chemin-du-Roy path - this way, you get to pass by all the bird colonies, including an elevated lookout for a real, ahem, bird's eye view of the action. Literally, there must've been over 10,000 gannets here (!), but somehow the park staff have done an amazing job of cordoning off the breeding grounds from the main path, and likewise, the gannets themselves seem to only stick by the cliffs and barely venturing inland.
For the gannets alone, it's worth the trip here, but there are also many other kinds of birds that frequent here such as the bald eagle, common murre, evening grosbeak, etc., in case you get bored!