One of the most important aspects of animal damage management, or any other kind of pest control, is determining the species you need to control. This is especially difficult for underground dwelling (fossorial) animals like moles and pocket gophers. If you live in an area where both occur, it is important to learn how to read the "signs," i.e., any evidence left behind by an animal's passage.
Both pocket gophers and moles make mounds, but they are significantly different looking. Fortunately, pocket gophers and moles typically inhabit different kinds of habitat. Pocket gophers typically occupy drier sites than do moles because gophers are herbivorous. Moles, on the other hand, typically occupy wetter sites than do gophers because they are insectivores that rely on the availability of earthworms, grubs, and other arthropods in the moist soil. This is the first step in distinguishing between the two: gophers dry, moles moist (typically).
The texture of the mounds also differs between gophers and moles. Typically, pocket gophers produce "tailings" (a term borrowed from the mining industry) that are relatively coarse in texture. This is due to the tools that gophers employ in excavating burrows: their claws and teeth. Moles produce tailings that are relatively fine-textured, partly because the soil they excavate is moist and partly because they exclusively use their comparatively small claws to dig. This is the second step in distinguishing between the two: gophers coarse, moles fine (typically).
The shape of mounds also differs considerably between gophers and moles. Typically, gophers produce a mound that is more or less dune-, fan-, or bean-shaped, with a visible, slightly crowned basal soil plug. Gopher mounds range from 8 inches to well over 12 inches, depending on the species. Mole mounds are evenly conical, without any visible plug. However, mole mounds may occasionally contain discrete "pods" or "packets" of soil. These represent the maximum amount of soil a mole can transport at one time. Pods are shaped by their passage through the mole's tunnel system. Mole mounds range from less than 6 inches across to over 12 inches across, again depending on the species. Moles also produce a unique kind of sign: surface runs. It is often said that moles "swim" through the soil. Looking much like veins immediately below the turf, these runs are the result of moles literally "swaging" a tunnel in moist soil, while deeper tunnels must be dug and always produce tailings. The third step in distinguishing between the two: gophers—dune-, fan-, or bean-shaped mounds with a visible plug; moles—evenly conical mounds without any plug, although "pods" or "packets" may be visible on fresh mounds. Moles also produce vein-like surface runs when they "swim" through the soil.