You’re walking alongside a beaver flowage and encounter large mustelid tracks – a bounding
pattern along the bank for more than 100 yards. Then the tracks cross the broad frozen pond,
whereupon they enter the forest and continue a meandering route up and over a distant ridge.
There are two possibilities: fisher or otter. Fishers will opportunistically visit and inspect wetland
and riparian habitats in search of mammal prey, birds, nuts, and lingering winter fruits. Otters
occasionally leave their semi-aquatic haunts and make beelines over hill and dale in search of other
streams and ponds. So which tracks are these? Here are some clues to help us sort things out.
Story and photos by Susan C. Morse
Fisher or Otter?
Northern Woodlands / Winter 2015
Fisher tracks are muffled-looking.
Occasionally tracks may show
clear toe and middle pad features,
but most do not because of the
abundant foot fur that covers
portions of the pads. Fisher feet
have no webbing. Also, note the
four protuberances on the surfaces
of both fisher and otter hind feet.
These are entrances to tiny
conduits that transfer glandular
secretions from within the foot
epidermis. These glands are
employed by both species for
Look at the track image and find
the front foot track; it is the one that
has a clear carpal pad impression
at the base of the track. Notice that
the front foot is bigger than the hind
foot, making it handy for grasping
and gripping prey that are attempting
Tracks may lead to evidence of
a male or female fisher’s unique
scent marking behaviors, especially
in late winter. Protruding stumps,
roots, and rotten logs that are
above the snow pack are mounted,
rubbed, and rolled upon. Feces,
urine, and fisher hairs will be found
at these scent stations.
Otter pad impressions are well-defined because the robust pad
surfaces are largely furless. This
enhances an otter’s sensory
abilities, enabling it to better feel
and secure hidden prey within
murky and muddy underwater
habitats. Otter tracks will also, at
some point, reliably register clear
mesial webbing – the webbing
unites the toes at the half-way
point. This webbing is unique to this
piscivorous swimming mustelid.
Hind foot tracks of otters are bigger
than their corresponding front foot
tracks, no doubt a helpful adaptation
because otters are swimmers.
Again, the carpal pad impression
helps us know which track was
made by the front foot.
Otter tracks will always lead back
to water where the characteristic
slide impressions are likely to be
seen. Lengthy slides with clean
edges, a consistent width, and a
smooth toboggan-like base are
the work of the otter’s Johnny
Weissmuller-like torso, the legs
tucked in for the length of the slide.
If it’s obvious that a good time was
being had, then it oughta be otter!
Susan C. Morse is founder and program
director of Keeping Track in Huntington,