Atlantic White-sided Dolphin
These seem to be relatively common. We went on a boat tour from the Bonavista Peninsula at the end of October and we found a super-pod of hundreds of them. The water all around the boat was boiling with them, it was an amazing sight. Apparently these super-pods are a fall occurrence, they are seen in smaller groups in the summer and can be hard to find in the spring.
I also saw a small pod of them looking out from my cabin near Carbonear, one of the Mad Rock Cabins. And I found a dead one washed up near St. Anthony.
White-beaked Dolphin
The Sea of Whales tour operator, who took us to see the white-sided dolphins, told us that spring is the time to see these around Bonavista, and he doesn't see them in the summer or fall.
I saw them only from the Cape Norman lighthouse on the Great Northern Peninsula, a well-known whale-watching spot. Their dorsal fins are so big that at a distance I had trouble telling them from (female) orcas!
Minke Whale
I saw these surface-feeding from the Cape Norman lighthouse, in association with the white-beaked dolphins. It was very neat to watch their huge mouths come out of the water and go along the surface.
Harbour Seals
Apparently they very common, but I noticed a distinct lack of seals the entire time I was in Newfoundland. People there absolutely hate seals; they get a lot of blame for keeping the cod stocks from recovering, and I suspect seals are harassed in a lot of places. This was particularly apparent when I took the ferry to St Pierre and immediately spotted seals hauled out around the harbour there.
On Newfoundland itself, just about the only place I found seals is around the southern end of the Avalon Peninsula, in particular in the harbours along the Irish Loop.
Hooded Seals
These were the only seals I found that were not habour seals. I saw a few of these hauled out with some harbour seals at the Mistaken Point Ecological Reserve, at the first point where the trail to Watern Cove looks out over the shoreline. I’m not sure if they’re regular there, I was there after a big storm and they might have just been resting up. Also, this is a famous location for Ediacaran fossils, unfortunately the places they are visible are only accessible on guided tour.
Birds
There are too many birds to list and discuss. My full list for Newfoundland can be found on my eBird profile here. It's lacking the most famous bird for the area - Atlantic puffin - as they move offshore outside the breeding season.
Newfoundland gets lots of vagrants. There were several warblers, some rare even for Canada, hanging around into December. I didn't chase them down, but if you're into that sort of thing it'd be worth checking out eBird, the Newfoundland Birders Google Group, and Jared Clarke's Twitter to see what's around.
Bald Eagle
Common soaring around the coast and over the highways, even a long way inland (probably because of all the ponds and lakes), but definitely not as easy to find as on the coast of British Columbia or Alaska. The whale watching tour out of Bonavista (Sea of Whales) took us to an active nest.
Rock Ptarmigan
Just about the only place you can find them is on the peaks of the Long Range Mountains in western Newfoundland, and just about the only accessible peak is Gros Morne. I was pleasantly surprised to see lots of them - upwards of 20 - while walking across the plateau. Not sure if that's normal or if its been a particularly good year for them.
Boreal Chickadee
I rarely see these elsewhere in Canada, so it was a pleasure to discover that they are probably the most common forest bird on the Avalon Peninsula, where the black-capped chickadee is rare. Further west on the island the black-capped gets progressively more common and the boreal harder to see.
White-winged Crossbill
Common across the island wherever there are conifers. A rare treat for me elsewhere in Canada, it was great to see them so frequently.
Northern Fulmar
Hard to see. I saw them once from shore after a big storm, and once from the ferry to St Pierre.