The answer is OPOSSUM.
Many of you were smarter than I was. For a long time I
tracked this area and thought these tracks were from muskrats. The
habitat threw me off - in winter, when their tracks & burrows are
most obvious, these opossums concentrate their activity around the pond,
which definitely has frequent sign of muskrat - scat, plunge holes in
the ice, and shells from feasts on freshwater clams.
For some reason that remains a mystery to me, the
opossums in my area stay in undeveloped areas & very close to water
during the winter; I almost never see their tracks in snow in
residential areas. But once spring arrives, they venture out of
the developed areas, crossing roads into residential areas and far from
water - the most obvious sign of this is road-killed opossums.
The indirect register is common to both opossum &
muskrat, and so is the star-shaped front footprint and the tendency to
drag the feet in shallow snow. The behavior of walking on the
skinny log, I don't
believe is indicative of either animal, but it wouldn't be inconsistent
with either animal.
The stride of 7-9", however, matches opossum better
than muskrat. And while both animals dig burrows, from what I know
muskrat burrows almost always have underwater entrances.
Opossums have thumbs that on their hind feet can point
backwards - you can see something akin to this in photo C8, but my
experience is that it's pretty rare when the thumb actually points
backwards like shown in the field guides.