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February Natural Mystery Answered

posted Mar 9, 2021, 4:34 PM by Jonathan Poppele   [ updated Mar 10, 2021, 8:56 AM ]
We received a small number of responses to February’s natural mystery, and no correct answers. So instead of sharing answers from contributors this month, I’ll share a few of my own notes on the tracks and the track pattern we can see in this photograph.

These are the tracks of an American Mink, moving in a 2x2 bound. Here is the description of American Mink tracks from the manuscript for my upcoming Animal Tracks of the Midwest, second edition:

"Mink leave classic mustelid tracks with five long toes and slender, crescent-shaped palms. Toes often splay widely and usually appear separated from the palm by a tall negative space, though the shaft of the toe is sometimes visible. Sharp claws usually register, sometimes as extensions of the toes giving them a pointy appearance. The thumb (toe 1) is the smallest, set the farthest back, and does not always register, but is more developed than in marten and long-tailed weasel. The palm has four pads, which may appear individually or fused, and is wider toward the outside of the track. Front tracks are slightly larger and usually more splayed than hinds. Front and hind tracks often overlap, creating jumbles of small pads.

Front tracks often splay widely, with all five toes radiating from the palm. At other times the middle toes (toes 2-4) register close together, resembling the hind track of a squirrel. There is a single pad on the heel, which sometimes registers.

Hind tracks are less symmetrical than fronts and usually less splayed. The “middle” and “ring” toes (toes 3 & 4) are set farther forward and sometimes register fairly close together as the outer toes splay. When the thumb (toe 1) does not register, the resulting 1-2-1 toe pattern can resemble the front track of a squirrel."

Some of the features in this photo that help point us toward mink include:
  • The single carpal pad visible on the front tracks.

  • The 2x2 track pattern, which is typical for many members of the weasel family traveling in snow.

  • The trail width of 3 ½”, is typical for mink and is outside the published range for long-tailed weasel.

  • The prints measure 1 ¼” wide. Front prints measure 1 ¾” long. These measurements put the tracks in the middle of the range for mink, at the extreme high end for long-tailed weasel, and below the published ranges for Marten (which are not found this far south).

The track pattern is an overlapping 2x2. This pattern is referred to as a 2x2 lope by some trackers and a 2x2 bound by others. I prefer the term 2x2 bound, because the mechanics of the gait that produces this pattern have more in common with the bound of a squirrel, which is characterized by an extended suspension, than with other lopes, which have only a gathered suspension. But lets break this down and explore how this animal was moving in more detail.

The mink traveled across this stretch of snow in a series of leaps. With each leap, the mink pushed off with its hind legs at close to the same time, with the left foot pushing off a little bit before the right. This is referred to as a “right lead,” because the right track appears farther forward in the tack pattern.

The leap was followed by a period of extended suspension. The mink had all four feet off the ground and its body was extended with the front legs reaching forward and the hind legs trailing behind. See illustration of a bounding mink just about to land, also from the Animal Tracks 2nd Ed manuscript. Note that this illustration depicts a left lead, rather than a right lead.

The mink landed on the right side of the photo, first with its left front (LF) foot, then with its right front (RF) foot. As it landed, its body contracted bringing the hind limbs close to the front limbs. The mink then lifted its LF off the ground and placed its left hind (LH) down just ahead of its LF track. Then the RF lifted and was replaced by the right hind (RH), setting the mink up for its next leap. The mink stayed in contact with the ground throughout this “gathered” phase of the gait.

The order of footfalls in this gait is a transverse (sometimes called “lateral”) sequence. The pattern is LF, RF, LH, RH, leap, LF, RF, LH, RH, leap.