The tree is an aspen (Populus tremuloides). I agree with Tom that some of the sporocarps don’t present in the normal P. tremulae fashion, but others in the set do look like typical sporocarps of this fungus.

I’ve been making an effort to more precisely identify the tree species around the area. Besides paper birch there seems to be a stand, in one area, of what might be quaking aspen instead, which has white bark.

I don’t suppose there’s a treeobserver.com that can ID trees from photos? The resources online for tree identification that I found are shockingly paltry and often primitive. A series of rows of name, leaf photo, twig-with-leaves photo, flower photo, fruit photo, young bark photo, old bark photo, young tree photo, and old tree photo would be useful, and none has this structure that I found, or an interactive system like MO uses for mushrooms.

I agree that this does not look like a white birch. Do you have other species of birch in your part of Ontario? Like gray birch? It looks more like aspen to me, but the fungi do not have the aspect of Phellinus tremulae— they stick out way too much. In any case great pictures with the telephot lens!

You sure? White bark, stature and leaves, etc. and the whole area is mainly birch/pine/spruce mixed…