FWS Focus

Overview

Characteristics
Overview

The Yelm pocket gopher is one of four federally-listed subspecies of Mazama pocket gopher in the state of Washington. It is found only in Thurston County. This small, burrowing, prairie-dependent rodent most likely declined with the disappearance in western Washington of the open prairies and grasslands upon which it depends.

Threats facing these subspecies include habitat fragmentation, degradation and loss due to development, military training and certain restoration actions. Additional threats include predation by domestic and feral dogs and cats, pest species control methods like trapping and poisoning, and small population effects. The loss of natural ecosystem maintenance processes on the landscape like natural wildfire cycles means all four subspecies of Mazama pocket gopher are conservation-reliant and will require active, ongoing management to maintain the prairie habitat characteristics needed for population growth and stability.

Additional Information on Mazama Pocket Gopher Recovery

STORY MAP: "Introducing... the Mazama Pocket Gopher"

Scientific Name

Thomomys mazama yelmensis
Common Name
Yelm pocket gopher
FWS Category
Mammals
Kingdom

Location in Taxonomic Tree

Identification Numbers

TSN:

Characteristics

Characteristic category

Physical Characteristics

Characteristics
Size & Shape

The Yelm subspecies of the Mazama pocket gopher is a small mammal ranging in length from 8 to 9 inches when measured from nose to tail. They are known as pocket gophers because they have fur-lined external pockets on either side of their mouth, similar to chipmunks. 

They have short tubular bodies and strong arms equipped with long pointed claws that allow them to move a tremendous amount of dirt. All of their teeth grow continuously throughout their lives, because they use their teeth along with their long curved claws to sift the roots of plants out of the dirt as they dig their tunnels. Although their vision is poor, their highly sensitive tails may assist in navigation through tunnels.

Color & Pattern

Yelm pocket gophers are blackish brown, although pelage color can change somewhat depending on the soils they inhabit.

Characteristic category

Life Cycle

Characteristics
Life Cycle

Mazama pocket gophers live an average of one to two years, though some may live longer. Sexual maturity is reached at one year of age. Males most likely mate with more than one female, but it is also likely that mating is based on female choice. Females are typically pregnant between 18 or 19 days before delivering a litter of five pups, on average. Unlike most other small rodents, or even other kinds of pocket gophers, Mazama pocket gophers only produce one litter of pups a year. Pups are altricial, meaning they are hairless, immobile, with closed eyes, and unable to obtain food on their own. The female raises the pups alone. By late summer or early fall, the mother will block the juvenile gophers out of the natal burrow, forcing them to disperse to the next nearest unoccupied tunnel system.

Characteristic category

Food

Characteristics
Food

Mazama pocket gophers get all of their water from the foods they eat, and so they prefer to eat succulent, nutrient-rich roots, shoots, bulbs and tubers. A few commonly-eaten foods include camas, hairy cat’s ear, lupine, phlox, dandelion, clover, woolly sunflower and violet, not all of which are native plants.

Characteristic category

Behavior

Characteristics
Behavior

Mazama pocket gophers are ecosystem engineers: their tunnel systems and mounds, which are made of excess soil from their tunneling activities, aerate the soil and provide vital nutrients for their grassland and prairie ecosystem. Although they are fossorial animals, spending most of their lives almost entirely underground, they may forage next to a mound opening to allow for a quick escape back into their tunnel systems. Juveniles may disperse above ground as well. Overall, Mazama pocket gophers typically forage from below-ground, clipping rootlets from forage plants, or pulling entire plants below ground into their foraging tunnels. They store plant clippings for later use in special caches designed to keep their food dry. Nest chambers serve many purposes, from safe places to rest and eat, to underground latrines - which are blocked off once full and later become a source of nutrients for grassland and prairie plants. In this manner, their tunnels systems are kept clean of detritus and dung.

Mazama pocket gophers are territorial, preferring to live alone in their tunnel systems. Tunnel systems are kept separate by virtue of one or more soil plugs between them. More than one gopher is found in the same tunnel system only during mating season or when the pups are still with their mother in the spring and summer months. Mazama pocket gophers do not hibernate during winter months, but stay active all year long.

Characteristic category

Habitat

Characteristics
Habitat

Roy Prairie, Olympia, Tenino and Yelm pocket gophers live in well-drained, easily-crumbled soil, which describes many of the prairie and grassland soils that were deposited in the south Puget Sound area of Washington State after the last glacial retreat, 10,000 to 12,000 years ago. Mazama pocket gophers don’t use soils that have a high clay or silt content, because clay soils are difficult for them to dig through and not as permeable to water, and both clay and highly silty soils are too wet for them to live in. Mazama pocket gophers also avoid extremely sandy soils that won’t hold the shape of a tunnel. Everywhere the Roy Prairie, Olympia, Tenino and Yelm pocket gophers occur, they occupy prairie-like habitat - areas that are relatively open, with short-statured vegetation and few woody plants. The number and size of rocks in the soil appear to strongly affect Mazama pocket gophers’ ability to make a living in what may look like otherwise suitable soils, as does the kind of vegetation growing on the soil. Short flowering plants and grasses are the kind of vegetation Mazama pocket gophers seem to like best. They avoid soils that are covered with forest or woody shrubs and Mazama pocket gophers can be crowded out by trees or invasive woody plants like Scotch broom.

Grassland

Ecosystem with large, flat areas of grasses.

Grassland

Ecosystem with large, flat areas of grasses.

Geography

Characteristics
Range

Mazama pocket gopher distribution in Thurston and Pierce counties, Washington has likely always been somewhat patchy, since the kinds of soils they’re capable of using are naturally patchy in distribution.

However, an estimated 95 percent of the prairie and grassland habitats for Mazama pocket gophers has been converted to other uses or developed for commercial or residential use. Fragmentation of their prairie and grassland habitats has led to smaller areas of suitable habitat, and occupied areas that are separated from each other by distances too far for a gopher to travel or too difficult for a gopher to cross.

Roy Prairie pocket gophers are known to occupy multiple large areas on Joint Base Lewis-McChord, and a few small, isolated sites off-base in and around the City of Roy. Isolated sites with marginal habitat may contain only small numbers of individuals while larger sites with good habitat may contain thousands of individuals.

Olympia pocket gophers are known to occupy a large area at the Olympia Airport, and multiple isolated sites scattered across its range. The Olympia Airport may contain thousands of individuals due to its size, while other sites contain hundreds or just tens of animals, due to their size and habitat quality.

Tenino pocket gophers are known to occupy the Rocky Prairie Natural Area Preserve, a small area managed by the Washington Department of Natural Resources. This single known population is thought to consist of only a few animals. Adjacent suitable habitat is thought to be occupied, but is unsurveyed.

Yelm pocket gophers are known to occupy multiple large areas across their range, on both federal Joint Base Lewis-McChord lands, state lands and private lands. They also occur on multiple isolated sites across their range. Isolated sites with marginal habitat may contain only small numbers of individuals while larger sites with good habitat may contain thousands of individuals.

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