It is determined by measuring the distance between the same foot tracks. Either heel to heel or nail to nail may be used. The way an animal walks can also be helpful in determining the species involved. Wild canids tend to walk straight, and their trails give the appearance that animal was on a bee-line . Quite often an imaginary line can be drawn through their tracks that is remarkably straight.
Dogs tend to meander quite a bit, giving their trials a zig-zag appearance.
Caution is warranted, and plenty of tracks is better that just a few to view The following key may be useful in identifying the various tracks that may by encountered in Wisconsin during winter months. Tracks of the three major groups of predators can be distinguished on the basis of track shape.