One of the challenges in a winter like the one we’ve been having is tracking in deep snow. Our native animals are mostly well equipped to cope with such conditions, but the evidence they leave can be mystifying–animals may change their habits, tracks and trails may look very different, and the details we generally rely on for identification may be absent. But the lives of animals are still written in the snow. To read these stories we just need to acquire some new reference images and expand our tracking skills.
A red fox made the trail shown below. In the deep snow the direct register walk was the most energy efficient gait, each hind foot coming down in the hole made by the front foot on the same side. Compared to walks in easier conditions the fox’s steps were shorter and its trail width was greater. The animal lifted its feet cleanly out of the snow, leaving just a few drag marks.
The direction of travel, from bottom to top, is revealed by the sprays of snow which fell off the feet as they rose out of the holes and moved forward. Whether animals are walking or moving at faster gaits–as long as their movements are regular and smooth–snow falling from their feet usually lands ahead of the tracks. Only during sudden acceleration or changes of direction do we see snow pushed backward or to the side.
A coyote walking from left to right made the trail in the next photo. The snow was less consolidated so there’s a softer appearance to the trail. The details in the track floors are obscured by the snow that fell in as the feet were lifted out, and the animal’s feet skimmed the soft surface leaving drag marks. Looking down into the holes (which is always a good idea in this kind of situation) we can see the shapes of the forward edges of the animal’s feet. The overall shape of a coyote’s foot is oval or egg-shaped, but how should we describe just the front half? The best I could come up with is parabolic or bluntly arched. Whether or not there’s a word for it, this shape is characteristic of coyotes and red foxes, and also some dogs. And there’s another feature that is typically canine: in the very tip of the hole on the right you can see two small dents made by the leading claws–a dead giveaway for a red fox or coyote. Gray foxes usually have more rounded leading edges and less tendency to show claw marks. Being shorter legged than red foxes, gray foxes are more likely to leave drag marks, and dogs are also prone to dragging their feet.
These two trails illustrate the general appearance of canine trails in deep snow. Because walks in deep snow tend to be very close to direct register it may be possible to get rough measurements for track widths, and this, plus stride or step length, can help to separate coyotes from red and gray foxes.
Bobcat trails in deep snow may be quite different from canine trails. In the photo below a bobcat walked from bottom to top, and at each step it spread its feet as they went down into the snow, creating a sequence of interlocking triangles. As usual, snow obscured the details of toes and pads at the bottoms of the holes, but in the lowermost impression you can see that the forward edge of the track is widely crescent-shaped rather than parabolic.
Sometimes animals negotiating deep snow move faster, perhaps out of fear or maybe just playful antics. In the photo below a red fox bounded from upper left to lower right, leaving holes where its body went in up to its shoulders. There may not be much information inside the holes, especially if the snow is loose and movable as it was when the photo was taken, but their width provides a rough measure of the width of the animal’s body. The level of effort required for this kind of movement means that it can’t be sustained for long periods, so following the trail either backwards of forward will probably bring you to a change of gait.
In spite of their long legs, deer are not well suited for moving in deep snow. Their feet are small in proportion to their body weight, so they sink in deeply. Deep drag marks like those in the photo below are typical, and sometimes the tips of the toes can be seen at the bottoms of the holes.
In deep snow deer may limit their movements to trails they’ve already made, such as the one in the next photo, where they can move with less effort. If the difficult conditions persist the animals may limit their movements to very restricted areas which become crisscrossed with trails. These deer yards are usually found under conifers, where the snow isn’t as deep and the evergreen foliage traps heat. When deer yard up the available browse is quickly eaten, so they eat very little, reduce their activity, and wait out the winter.
For short-legged animals like porcupines, skunks, and muskrats the only option in deep snow is to bulldoze their way through. In the photo below a skunk struggled from upper left to lower right, its body plowing through the snow and its feet punching deep holes in the bottom of the groove. The small pits made by the feet, combined with the short strides and wide trail width are good indicators of the animal’s identity.
When temperatures fluctuate or sun melts the surface, snow can develop an icy crust. Sometimes this reduces the problem of movement, allowing lighter animals to move easily over the surface. But if the hardness of the crust varies or the animal is just a little too heavy, we may find scenes like the one in the photo below. A coyote attempting to cross a drift found that it wasn’t always supported by the crust. Where it broke through it left crisp outlines of its lower legs and spread toes.
Like other animals, rabbits and squirrels can plunge deeply into snow, and this can make it hard to identify their tracks. But the difference in the positioning of the front feet usually provides a clue to the animal’s identity. The next photo shows a cavity made by a gray squirrel bounding from lower left to upper right. Inside the hole there are two depressions, each one made by a front foot and a rear foot from the same side. The wide separation of the depressions and the equally wide entry and exit disturbances give the hole a boxy or rectangular shape.
Compare that to the next photo of a rabbit in deep snow, also bounding from lower left to upper right. Because the rabbit brought its front feet down on or close to the center line of the trail, the entry point (at the lower left) is narrow. The rear feet made a wide depression in the deepest part of the hole and left separated drag marks coming out. The result is a triangular cavity with the wide end opening toward the direction of travel.
Maybe the biggest hinderance to learning how animals move in deep snow is just getting out into the stuff. You’ll need snowshoes or skis, or at the very least good gaiters, to get close to the tracks. But if you spend some extra time arranging all your gear you’ll be rewarded with a deep look into the lives of animals in deep snow.