Guest post by Todd West, Friends of the Central Cascades Wilderness.
American martens (Martes americana) share habitat with montane red foxes (Vulpes vulpes cascadensis, V. v. necator) and coyotes (Canis latrans), and their scats are often encountered along trails when we look for fox sign. As the smallest of these three carnivores, their scats are also the smallest, typically 1/4 of an inch in diameter or a little bigger (5-8mm) and two to four inches long (5-10 cm). Practice is needed to consistently distinguish them. Often bent or curled up, marten scats are dark in color, often dark green, and commonly exhibit a plated look from curls of hair within the scat. Over time, digested material will erode away from the scats, leaving bundles of curled hair. Larger marten scats occasional exceed 3/8 of an inch diameter (10 mm) and five inches length (13 cm), approaching the size of red fox scats. However, they can be distinguished from fox scats by their twisty ends and tighter plating compared to the tubular look of fox scats.
Here are a few photos of individual marten scats which have been identify by DNA sequencing.
Hair bundles from several older marten scats appear in the photo below. This sample was also mtDNA confirmed.
The remainder of the photos below are of scats which have been visually identified as marten but not mtDNA sequenced. As above, a variety of size, shape, and dryness is shown.
When berries are available scats shift color and consistency. This marten had apparently been consuming ripe huckleberries in the Mount Washington Wilderness.
It is common to encounter multiple scats near each other. In this case an older marten scat appears at upper left with a fresher one at lower right.
As with other species, scats are typically left in the middle of the trail and less commonly along the sides. If a trail has prominences, such as rocks or roots, in its tread martens may preferred these locations for scats. The rock below provided a step in the middle of the trail with two fresher scats at left and an older, somewhat rain spread, scat at right.
Scat grouping also occurs across species. In the below example the small, fresher marten scat just above the GPS was laid next to a coyote scat (also visually identified and not DNA tested).
Marten scats may be left repeatedly in some areas, increasing the size of the group. The below image contains three or perhaps four scats of increasing age. Larger groups often have additional smaller groups nearby, with occasionally as many as 7 to 15 scats within a 20 foot radius (6 m).