POCKET GOPHERS: Geomyidae

PHYSICAL CHARACTERISTICS

Pocket gophers have stout, heavy set bodies that have a tube-like shape. The length of their bodies varies depending upon the species from 5 to 14 inches (13 to 36 centimeters). Males are generally larger than females. Their legs are relatively short and powerful. The five claws on their thick front legs are long, sharp, and curved. The third claw is the longest. Their hands are broad.

The pocket gopher does not appear to have a neck. They have short, almost hairless tails, which are extremely sensitive to the touch. Eyes and ears are small, and surrounded by numerous hairs that prevent soil from getting in. They have large and sharp incisors, chisel-shaped teeth at the front of the mouth. They also have whiskers that extend from their nose.

The "pocket" part of their name refers to fur-lined pouches, one on each side of their mouth, in which they carry food. The name gopher comes from the French word gaufre meaning waffle or honeycomb, and refers to the network of passages that it digs. The pouches open into the mouth and extend from the mouth region back to the shoulders. When filled with food, the pouches make the pocket gopher's head appear almost twice its size. Pocket gophers can turn these pouches inside out for cleaning.

Pocket gophers have loose and flexible skin. The skin is thick around the head and throat. Fur color varies widely, even within a species. The color generally matches the color of freshly turned soil, a light brown to almost black. Fur is generally soft, and is short in species living in hot environments.

GEOGRAPHIC RANGE

Pocket gophers are found in North America and extend into Central America. They are found from southern Canada through western North America, southward to northwestern Colombia in South America. One species occurs in the southeastern United States, in Alabama, Georgia, and Florida.

HABITAT

Pocket gophers live in almost any area that has soil that they can dig. They are found in meadows, forests, deserts, rainforests, and fields, from dry, extremely hot, climates at sea level to extremely cold climates in mountainous areas. They do not travel far, and occur in isolated areas. They spend most of their lives underground, though they surface at times to gather food. In certain parts of the country, the older animals may move to moister areas during dry periods.

DIET

Pocket gophers are herbivores, plant eaters. These animals feed primarily on the underground parts of plants, especially the roots, bulbs, and tubers. They also cut stems and carry them in their cheek pouches to their storage chambers.

BEHAVIOR AND REPRODUCTION

Pocket gophers are rarely seen because they spend almost their entire lives underground. Also, these animals are generally crepuscular (kri-PUS-kyuh-lur), active at dawn and dusk, and some are nocturnal, active at night. Pocket gophers do not hibernate, go into a resting state to conserve energy, and in general, are active year round.

These animals forage, look for food, through the ground, burrowing, or digging, a set of complex tunnels. Where the digging is easy, pocket gophers are able to tunnel as much as 200 to 300 feet (61 to 91 meters) in a single night. They dig primarily with their powerful front claws. They use their upper incisors to cut roots and loosen soil and rocks. They use their sensitive tail and whiskers to feel their way around in the dark.

Pocket gophers generally dig two kinds of tunnels. One type of tunnel is long, winding, and shallow. They use this type to get food from above. The second type of tunnel is deeper. They use these tunnels for shelter, with chambers for nests, food storage, and fecal, waste, deposits. The tunnels are usually marked above ground by small mounds of earth. When not in use, these animals plug up burrow entrances with dirt. Pocket gophers can run backward in their burrows almost as fast as they can run forward. Burrows may be occupied by the same animal for several years and spread over an acre (0.4 hectares) of ground.

Pocket gophers are extremely unsocial. They live alone in their burrow system. When one pocket gopher meets another, they squeal and hiss at one another, and their teeth chatter. They may fight violently. One is often killed in the fight.

The only time pocket gophers spend time with others of their species is during the mating season. Generally in the spring, the male leaves his den and briefly goes into the burrow of a female. Pocket gophers typically breed only once per year, although some species are capable of breeding in the spring and fall. Gestation, pregnancy, ranges from eighteen to more than thirty days, with the smaller species having the lower gestation times. Litter size varies from one to ten offspring. Until they are five weeks old the babies' eyes and ears are sealed shut. Offspring stay with the mother in the burrow for one to two months, and then each sets off to burrow its own system of tunnels.

POCKET GOPHERS AND PEOPLE

Pocket gophers play an important role in the ecosystem in which they live. They loosen and enrich the soil when they burrow. The occupied or abandoned burrows of these rodents are used extensively by other animals for shelter or foraging.

POCKET GOPHERS AND CHEWING LICE

Studies have shown that relationships among species of pocket gophers mirror relationships among species of chewing lice, suggesting they have a long history of living together. Lice are small organisms that live, grow, and eat on other organisms. When pocket gophers mate, the lice on one gopher can jump to the other gopher to mate with the lice infesting it. Since pocket gophers mate only with their own species, the lice are limited to mating with other lice that live on that same species of pocket gopher. In this way, as pocket gophers formed separate species, the lice that live on them are also likely to form separate species.

Some people consider these animals to be pests. In some areas, a single pocket gopher can destroy a family garden in less than a month. Their burrows can harm agricultural fields, causing extensive crop damage. They can consume a great deal of the underground parts of plants. Commercial farmers may trap and poison pocket gophers. Humans have also destroyed or altered these animals natural habitat, causing a decline in the population of some of these species. Some people in Latin America consider the meat of the pocket gopher to be a delicacy, luxury.

CONSERVATION STATUS

The World Conservation Union (IUCN) lists fifteen species of pocket gophers as threatened. The Oaxacan (wah-HAH-kan) pocket gopher and Querétaro pocket gopher are listed as Critically Endangered, facing an extremely high risk of extinction. The Michoacan pocket gopher is considered Endangered, facing a high risk of extinction.

VALLEY POCKET GOPHER (Thomomys bottae): SPECIES ACCOUNT

Physical characteristics: The valley pocket gopher is also commonly know as Botta's pocket gopher, smooth-toothed pocket gopher, and western pocket gopher. Valley pocket gophers have a combined head and body length of 6 to 13 inches (15 to 33 centimeters). Claws on their front feet are relatively small. Fur color varies among individuals, ranging from pale gray to reddish brown to black. The belly is grayish white, white, light yellowish brown, or mottled, splotched. An identifying characteristic of these animals is a single indistinct groove on each incisor.

Geographic range: Valley pocket gophers are found in the western United States into northern Mexico. They can live at altitudes from sea level to 10,000 feet (3,000 meters).

Habitat: These animals can live in a wide range of habitats. They occur in soils ranging from loose sands to tight clays, and in dry deserts to mountainous meadows. They commonly live in valleys, woodlands, deserts, and agricultural fields.

Diet: Valley pocket gophers feed on below ground plants such as roots and tubers. They especially like the roots of alfalfa. From its root, pocket gophers can pull the entire plant into its burrow to eat or store the food. They will also come to the surface to feed and clip off vegetation near the entrance of their burrow.

Behavior and reproduction: Valley pocket gophers are solitary animals that are active throughout the year. They burrow a system of tunnels and spend about 90 percent of their time below ground.

During the breeding season males will briefly join females in their burrows. The main breeding season is in spring, however these animals will sometimes breed in the fall also. Females generally bear two to four offspring per litter.

Valley pocket gophers and people: Farmers and gardeners may consider these animals pests. Valley pocket gophers can be destructive to plants, and people will trap or poison them. Yet the burrowing activity of these animals cultivates the soil, and vegetation and many organisms are dependent upon their continued activity.

Conservation status: This species is not listed as threatened by the IUCN. ∎

FOR MORE INFORMATION

Books:

Clutton-Brock, Juliet, and Don E. Wilson, ed. consultants. Smithsonian Handbooks: Mammals. New York: Dorling Kindersley Publishing, 2002.

Macdonald, David, ed. The Encyclopedia of Mammals. New York: Facts on File Publications, 1984.

Nowak, Ronald M. Walker's Mammals of the World, 5th ed. Baltimore and London: The Johns Hopkins University Press, 1991.

Nowak, Ronald M. "Pocket Gophers." Walker's Mammals of the World Online 5.1. Baltimore: Johns Hopkins University Press, 1997. http://www.press.jhu.edu/books/walkers_mammals_of_the_world/rodentia/rodentia.geomyidae.html (accessed on July 7, 2004).

Periodicals:

Benedix, J. H. Jr. "A Predictable Pattern of Daily Activity by the Pocket Gopher Geomys bursarius." Animal Behaviour (September 1994): 501–509.

Brower, Kenneth. "The Proof is in the Pellet." Audubon (March 2004): 78.

Web sites:

Myers, P. "Family Geomyidae (Pocket Gophers)." Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/information/Geomyidae.html (accessed on July 7, 2004).

"Pocket Gophers." Colorado Division of Wildlife. http://wildlife.state.co.us/Education/mammalsguide/pocket_gophers.asp (accessed on July 7, 2004).

"The Pocket Gopher." Forest Preserve District of Cook County (Illinois). http://www.newton.dep.anl.gov/natbltn/400-499/nb493.htm (accessed on July 7, 2004).