It is rare that a perfect track is discovered in the wild -- one that would help to easily identify the animal that left it with the use of a field guide. Tracks often become smudged or only a partial imprint of the animal's foot is made in the dirt, mud, snow, or other medium. But there are some things the experienced tracker will look for that can give away which creature left behind a track.
It is important when trying to determine what made a specific track to get as much data as possible concerning the track. This includes the length and width of the track as well as its shape and whether or not the track is showing the pads of the feet and/or toes. The number of toes and even the presence of claw marks at the end of the toes can give away an animal's identity. The distance between the track and the environment in which the track was discovered are also important features that can aid in finding out what made the imprint.
One of the most useful tools in track identification is to determine the number of toes the animal has. Rodents, for example, all have five toes on the hind feet but just four on the front. Members of the weasel family such as the skunk, mink, otter, and badger have five toes on both the front and hind feet. The cats of North America such as the lynx, bobcat, and cougar have four toes but do not typically leave the imprint of their claws in a track while canines such as the fox, coyote, and wolf possess four toes on each foot but do leave claw markings behind.
Ungulates, or hoofed mammals, can present a challenge when they leave their tracks behind. However, by knowing what type of ungulates live in a certain region of the country, using process of elimination an individual may be able to identify the track. Most members of the deer family leave behind a somewhat heart-shaped two-toed track, with subtle differences between the species in the size and shape of the individual toes that can help someone recognize what made it.