There are many subspecies because they are easily isolated by rocky, wet, or very compact soil; by frequent agricultural plowing of the land; or by dense forest (Whitmer, 1996).
Perception Channels: tactile ; chemical
As of 1998 T. mazama was listed as a candidate species by the Washington Department of Fish and Wildlife and as a species of concern by the U.S. Fish and Wildlife Service but was not included in lists of threatened species from the Oregon Department of Fish and Wildlife or the California Department of Fish and Game (Verts and Carraway, 2000).
IUCN Red List of Threatened Species: least concern
Thomomys mazama can cause the failure of forest plantings because they eat the roots, leaves, and stems of the seedlings. This has led to efforts to control and eliminate gopher populations with repellents and toxins (Witmer, 2000).
Negative Impacts: crop pest
Thomomys mazama may play an important role in the aeration, mixing, and drainage of soil. They also contribute to the distribution and succession of plant species and communities. They are a source of food to many mammals and birds. Their burrows are used and inhabited by many other species. Their ecological importance is suggested by the fact that there is an ecological equivalent to the gopher on almost every continent (Witmer, 1996).
Ecosystem Impact: disperses seeds; creates habitat; soil aeration
Grasses compose the largest portion of the diet of T. mazama annually. Woody plants such as Ponderosa pine were consumed mostly in the winter. Roots were eaten mostly in the autumn and spring and compose a large portion of the diet during these periods. Forbs are preferred when many food sources are available. In general, consumption of various species of plants corresponded to their abundance (Verts and Carraway, 2000).
Thomomys mazama is found in the Pacific Northwest of the United States. Populations occur in Washington, Oregon, and California (Verts and Carraway, 2000).
Thomomys mazama usually occupies a narrower array of niches than other species of Thomomys. Thomomys mazama is found in a variety of soil types in prairies, meadows, orchards, and abandoned farms. They are not frequently found in dense forest. Common vegetation in the habitats of T. mazama includes bracken fern, Douglas fir, perennial grasses, red sorrel, and western strawberry.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: savanna or grassland
Other Habitat Features: agricultural
Thomomys mazama is highly fossorial. It is adapted for this mode of life with heavily muscled shoulders and head tapering to relatively narrow hips. It has short limbs with five toes on each of the four feet. The toes on the front limbs have much longer curved claws than the hind limbs. The eyes and ears are small. The skull is flattened dorso-ventrally and has wide spreading zygomatic arches. The mandibles are heavy (Verts and Carraway, 2000).
The dorsal pelage of T. mazama exhibits a large range of colors in various subspecies. It is a shiny iridescent black in the subspecies T. m. niger. In T. m. tumuli and T. m. pugetensis it is blackish brown. The fur is dark brown in T. m. fuscus and T. m. louiei; reddish brown in T. m. hesperus, T. m. mazama, T. m. helleri, and T. m. melanops; reddish tan in T. m. couchi and T. m. tacomensis; light yellowish brown in T. m. nasicus, T. m. premaxillaris, and T. m. glacialis; and light brown in T. m. oregonus and T. m. yelmensis. The nose and face are dusky or black. The chest often has white splotches. The tip of the tail is lighter colored, usually buff, white, or light gray and may be almost naked.
Male T. mazama are generally larger than females. The total average length of T. mazama is 204 mm for females and 213 mm for males. The average tail length is 62 mm for females and 64.5 mm for males. The baculum is commonly used to differentiate between juveniles and adults. It is long and slender. The minimum length to be classified as an adult is 21-22 mm, but it can reach a length of about 26 mm. The dental formula for T. mazama is i 1/1 c 0/0 p 1/1 m 3/3 with a total of 20 teeth. The premolars are figure eight shaped. Chewing is propalinal (Verts and Carraway, 2000).
Range length: 204 to 213 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
Anti-predator adaptations are primarily behavioral. Thomamys mazama lives underground and emerges only briefly at night to forage. If threatened it retreats underground (Verts and Carraway, 2000).
Known Predators:
There is little information on the mating behavior of T. mazama. Individuals seem to rely on encountering each other through normal daily movement (Scheffer, 1938).
Mating has not been observed in captivity for T. mazama, but reproductive behavior can be inferred from individuals taken in from the wild. The females produce one litter per year during the October to June breeding season. The average litter size is five. The period of gestation is about one month and depends on environmental factors. Under extreme stress, one or more embryos may be reabsorbed (Scheffer, 1938).
Average number of offspring: 5.
Average gestation period: 30 days.
Average age at sexual or reproductive maturity (female): 1 months.
Average age at sexual or reproductive maturity (male): 1 months.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal )
Average gestation period: 30 days.
Average number of offspring: 5.
The Mazama pocket gopher (Thomomys mazama) is a smooth-toothed pocket gopher restricted to the Pacific Northwest. The herbivorous species ranges from coastal Washington, through Oregon, and into north-central California. Four subspecies of the Mazama Pocket Gopher are classified as threatened under the Endangered Species Act of 1973, including T. m. pugetensis (Olympia pocket gopher), T. m. tumuli (Tenino pocket gopher), T. m. glacialis (Roy Prairie pocket gopher), and T. m. yelmensis (Yelm pocket gopher).[4] The Mazama Pocket Gopher is one of the smallest of 35 species in the pocket gopher family.[5]
Mazama pocket gophers are light brown to black in color, with adults ranging in size from 5 to 6 inches (13 to 15 cm) in length. The Mazama pocket gopher’s distinctive features include pointed claws, long whiskers, and protruding chisel-like front teeth.[6] The pocket gopher serves as prey for a variety of predatory species. The species has poor vision, but excels at digging burrows with their long claws and strong limbs and its burrows are used by a number of other species.[7]
The gophers transport food and nesting material by fur pouches on their bodies and pockets within their cheeks.[7] The gopher's diet consists of plant material, mostly vegetation, roots and tubers. According to a study conducted in South-Central Oregon between 1973 and 1974, the Mazama Pocket Gopher’s diet consists mostly of above ground parts of forbs, grasses, woody plants, and plant roots. These comprised 40%, 32%, 4%, and 24% of their diet, respectively, by volume, per a study which examined the contents of the stomachs of 110 Mazama Pocket Gophers. The diet of the Mazama Pocket Gopher adapts to the availability of different foods, however they tend to choose the most succulent foods available throughout the year.[8]
The gophers exhibit asocial behaviors except during the gestation and mating season. Mating is believed to be polygamous. Gestation lasts around 18 days, with each litter averaging 3 or 4 young. Females will usually have one litter per year between March and June.[9] Pocket gophers form an angled tunnel in the ground as they dig for roots to eat. In this process, they transform the soil into a soft and sifted powder, in turn creating a unique, irregularly shaped mound with an off-center hole.
The Mazama pocket gopher is important to the prairie ecosystem it inhabits. Each gopher is capable of turning over 3–7 tons of soil per acre per year. Their presence is beneficial for plant diversity, with one study showing 5–48% higher as a result. Frogs, toads, small mammals and lizards also use their gopher burrows.[10] Pocket gophers form an angled tunnel in the ground as they dig for roots to eat. In this process, they transform the soil into a soft and sifted powder, in turn creating a unique, irregularly shaped mound with an off-center hole.[6]
The Mazama Pocket Gopher is mainly local to areas with herbaceous vegetation and well-drained glacial soil.[7] The total population is unknown, but believed to exceed 100,000, a majority of population resides in the state of Oregon. There are 27 known populations in the state of Washington, with an estimated 2000–5000 individuals total.[1] The state of Washington has listed the Mazama pocket gopher and its subspecies found in the Puget Sound area as threatened.
The Mazama pocket gopher in Washington has suffered habitat loss, with the remaining habitats being located in unexpected places. The largest populations have been found to reside around Fort Lewis and several regional airports.[9][11] The Olympic National Park cited as another possible location for a sizable population.[9]
A 2005 study reported 6000 gophers living around Olympia airport, but this study has been criticized for its conclusions. The study made count of burrows and did not engage in trapping and marking to estimate the actual number of gophers present. The population is also known to vary erratically, increasing dramatically after the mating season and declining as the year progresses due to predation.[10] This contradicts the estimated population listed on the IUCN database which lists between 2000-5000 gophers in the state of Washington with the isolated populations being representative of all 27 populations.[1] The population of the subspecies indigenous to the area is unknown, with two of the sub-species presumed extinct and Thomomys mazama douglasii's status being uncertain and possibly extinct.[12]
The species is currently listed as threatened by the state of Washington.[10] In December 2012, a proposal was made by the U.S. Fish and Wildlife Service to list the gopher as threatened. It would apply to the four local subspecies of the Mazama pocket gopher and their prairie habitat. Their prairie habitat in which the gophers live has been reduced by 90–95% in the last 150 years.[13] A translocation project has been undertaken, but a mortality of 90% has been reported.[10]
The gopher is also listed as a pest in the state of Washington because it is known to cause damage to infrastructure. The gophers can destroy waterlines, endanger livestock, destroy crops and weaken levees and dams.[14]
The conservation of the species has been met with some press coverage. In July 2013, Fox News ran a story about Fort Lewis's $3.5 million grant from the state of Washington to purchase 2,600 acres (1,100 ha) of land during a time when workers were on furlough.[15] Prior to this story, the grant was described by Interior Secretary Sally Jewell as "...taking an important step in addressing one of the greatest threats to wildlife in America today, loss of habitat, while helping to ensure the preservation of working landscapes and our military readiness."[16]
The gophers are known to cause damage to farms and infrastructure through burrowing or consuming vegetation. Damage mitigation can be done by installing a gopher fence, which has to be at least 6 inches (15 cm) above ground and go down to a depth of over 2 feet (0.61 m) or until bedrock or hardpan is struck. This fence is considered a temporary and not permanent defense against the gophers. Gophers are unlikely to be deterred by frightening devices like vibrating stakes, pinwheels and other sound devices. While other methods of control exist, the state of Washington's listing of the species as threatened limits control methods to non-lethal actions.[17] Since pocket gophers feed on conifer seedlings, they threaten reforestation in the Pacific Northwest.[8] Forest management can effectively control Mazama Gophers by altering the vegetation to no longer support the species.
It is a member of the family Geomyidae and its genus is Thomomys. The Geomyidae family is a group of New World rodents that is related to the Heteromyidae.[7] Thomomys is the classification for western pocket gophers, a smooth-toothed pocket gopher without grooves on their incisors. The Mazama pocket gopher takes its species name from Mount Mazama, the ancient volcano that exploded 6,000 years ago to form Crater Lake in Oregon, where the species was first found.[18] Despite its name, it does not appear in Mazama, Washington.
Subspecies of the Mazama pocket gopher include:
The Mazama pocket gopher (Thomomys mazama) is a smooth-toothed pocket gopher restricted to the Pacific Northwest. The herbivorous species ranges from coastal Washington, through Oregon, and into north-central California. Four subspecies of the Mazama Pocket Gopher are classified as threatened under the Endangered Species Act of 1973, including T. m. pugetensis (Olympia pocket gopher), T. m. tumuli (Tenino pocket gopher), T. m. glacialis (Roy Prairie pocket gopher), and T. m. yelmensis (Yelm pocket gopher). The Mazama Pocket Gopher is one of the smallest of 35 species in the pocket gopher family.
