The Pine Trail leaves the Birch Loop after a short distance and quickly makes its way to a large beaver pond. This is the same beaver pond that the Black Bay Beaver Pond Trail ends at. I saw two beaver lodges on the pond and skied off trail to have a look. The one at the further end of the pond is quite large.
There were more beaver ponds on the back section,
Update of January 31, 2017:Today I headed back to the Black Bay Trails. This time I would ski the Ridge Loop, which is rated as difficult. I started off on the easy Birch Loop
One of the most interesting parts of the Ridge Trail was a large beaver pond that it traversed.